livecodingspace-app/public/lib/fun/ramda.js

//  Ramda v0.25.0
//  https://github.com/ramda/ramda
//  (c) 2013-2018 Scott Sauyet, Michael Hurley, and David Chambers
//  Ramda may be freely distributed under the MIT license.

(function (global, factory) {
	typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
	typeof define === 'function' && define.amd ? define(['exports'], factory) :
	(factory((global.R = {})));
}(this, (function (exports) { 'use strict';

/**
 * A function that always returns `false`. Any passed in parameters are ignored.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Function
 * @sig * -> Boolean
 * @param {*}
 * @return {Boolean}
 * @see R.T
 * @example
 *
 *      R.F(); //=> false
 */
var F = function() {return false;};

/**
 * A function that always returns `true`. Any passed in parameters are ignored.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Function
 * @sig * -> Boolean
 * @param {*}
 * @return {Boolean}
 * @see R.F
 * @example
 *
 *      R.T(); //=> true
 */
var T = function() {return true;};

/**
 * A special placeholder value used to specify "gaps" within curried functions,
 * allowing partial application of any combination of arguments, regardless of
 * their positions.
 *
 * If `g` is a curried ternary function and `_` is `R.__`, the following are
 * equivalent:
 *
 *   - `g(1, 2, 3)`
 *   - `g(_, 2, 3)(1)`
 *   - `g(_, _, 3)(1)(2)`
 *   - `g(_, _, 3)(1, 2)`
 *   - `g(_, 2, _)(1, 3)`
 *   - `g(_, 2)(1)(3)`
 *   - `g(_, 2)(1, 3)`
 *   - `g(_, 2)(_, 3)(1)`
 *
 * @name __
 * @constant
 * @memberOf R
 * @since v0.6.0
 * @category Function
 * @example
 *
 *      const greet = R.replace('{name}', R.__, 'Hello, {name}!');
 *      greet('Alice'); //=> 'Hello, Alice!'
 */
var __ = {'@@functional/placeholder': true};

function _isPlaceholder(a) {
  return a != null &&
         typeof a === 'object' &&
         a['@@functional/placeholder'] === true;
}

/**
 * Optimized internal one-arity curry function.
 *
 * @private
 * @category Function
 * @param {Function} fn The function to curry.
 * @return {Function} The curried function.
 */
function _curry1(fn) {
  return function f1(a) {
    if (arguments.length === 0 || _isPlaceholder(a)) {
      return f1;
    } else {
      return fn.apply(this, arguments);
    }
  };
}

/**
 * Optimized internal two-arity curry function.
 *
 * @private
 * @category Function
 * @param {Function} fn The function to curry.
 * @return {Function} The curried function.
 */
function _curry2(fn) {
  return function f2(a, b) {
    switch (arguments.length) {
      case 0:
        return f2;
      case 1:
        return _isPlaceholder(a) ? f2
             : _curry1(function(_b) { return fn(a, _b); });
      default:
        return _isPlaceholder(a) && _isPlaceholder(b) ? f2
             : _isPlaceholder(a) ? _curry1(function(_a) { return fn(_a, b); })
             : _isPlaceholder(b) ? _curry1(function(_b) { return fn(a, _b); })
             : fn(a, b);
    }
  };
}

/**
 * Adds two values.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Math
 * @sig Number -> Number -> Number
 * @param {Number} a
 * @param {Number} b
 * @return {Number}
 * @see R.subtract
 * @example
 *
 *      R.add(2, 3);       //=>  5
 *      R.add(7)(10);      //=> 17
 */
var add = _curry2(function add(a, b) {
  return Number(a) + Number(b);
});

/**
 * Private `concat` function to merge two array-like objects.
 *
 * @private
 * @param {Array|Arguments} [set1=[]] An array-like object.
 * @param {Array|Arguments} [set2=[]] An array-like object.
 * @return {Array} A new, merged array.
 * @example
 *
 *      _concat([4, 5, 6], [1, 2, 3]); //=> [4, 5, 6, 1, 2, 3]
 */
function _concat(set1, set2) {
  set1 = set1 || [];
  set2 = set2 || [];
  var idx;
  var len1 = set1.length;
  var len2 = set2.length;
  var result = [];

  idx = 0;
  while (idx < len1) {
    result[result.length] = set1[idx];
    idx += 1;
  }
  idx = 0;
  while (idx < len2) {
    result[result.length] = set2[idx];
    idx += 1;
  }
  return result;
}

function _arity(n, fn) {
  /* eslint-disable no-unused-vars */
  switch (n) {
    case 0: return function() { return fn.apply(this, arguments); };
    case 1: return function(a0) { return fn.apply(this, arguments); };
    case 2: return function(a0, a1) { return fn.apply(this, arguments); };
    case 3: return function(a0, a1, a2) { return fn.apply(this, arguments); };
    case 4: return function(a0, a1, a2, a3) { return fn.apply(this, arguments); };
    case 5: return function(a0, a1, a2, a3, a4) { return fn.apply(this, arguments); };
    case 6: return function(a0, a1, a2, a3, a4, a5) { return fn.apply(this, arguments); };
    case 7: return function(a0, a1, a2, a3, a4, a5, a6) { return fn.apply(this, arguments); };
    case 8: return function(a0, a1, a2, a3, a4, a5, a6, a7) { return fn.apply(this, arguments); };
    case 9: return function(a0, a1, a2, a3, a4, a5, a6, a7, a8) { return fn.apply(this, arguments); };
    case 10: return function(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9) { return fn.apply(this, arguments); };
    default: throw new Error('First argument to _arity must be a non-negative integer no greater than ten');
  }
}

/**
 * Internal curryN function.
 *
 * @private
 * @category Function
 * @param {Number} length The arity of the curried function.
 * @param {Array} received An array of arguments received thus far.
 * @param {Function} fn The function to curry.
 * @return {Function} The curried function.
 */
function _curryN(length, received, fn) {
  return function() {
    var combined = [];
    var argsIdx = 0;
    var left = length;
    var combinedIdx = 0;
    while (combinedIdx < received.length || argsIdx < arguments.length) {
      var result;
      if (combinedIdx < received.length &&
          (!_isPlaceholder(received[combinedIdx]) ||
           argsIdx >= arguments.length)) {
        result = received[combinedIdx];
      } else {
        result = arguments[argsIdx];
        argsIdx += 1;
      }
      combined[combinedIdx] = result;
      if (!_isPlaceholder(result)) {
        left -= 1;
      }
      combinedIdx += 1;
    }
    return left <= 0 ? fn.apply(this, combined)
                     : _arity(left, _curryN(length, combined, fn));
  };
}

/**
 * Returns a curried equivalent of the provided function, with the specified
 * arity. The curried function has two unusual capabilities. First, its
 * arguments needn't be provided one at a time. If `g` is `R.curryN(3, f)`, the
 * following are equivalent:
 *
 *   - `g(1)(2)(3)`
 *   - `g(1)(2, 3)`
 *   - `g(1, 2)(3)`
 *   - `g(1, 2, 3)`
 *
 * Secondly, the special placeholder value [`R.__`](#__) may be used to specify
 * "gaps", allowing partial application of any combination of arguments,
 * regardless of their positions. If `g` is as above and `_` is [`R.__`](#__),
 * the following are equivalent:
 *
 *   - `g(1, 2, 3)`
 *   - `g(_, 2, 3)(1)`
 *   - `g(_, _, 3)(1)(2)`
 *   - `g(_, _, 3)(1, 2)`
 *   - `g(_, 2)(1)(3)`
 *   - `g(_, 2)(1, 3)`
 *   - `g(_, 2)(_, 3)(1)`
 *
 * @func
 * @memberOf R
 * @since v0.5.0
 * @category Function
 * @sig Number -> (* -> a) -> (* -> a)
 * @param {Number} length The arity for the returned function.
 * @param {Function} fn The function to curry.
 * @return {Function} A new, curried function.
 * @see R.curry
 * @example
 *
 *      const sumArgs = (...args) => R.sum(args);
 *
 *      const curriedAddFourNumbers = R.curryN(4, sumArgs);
 *      const f = curriedAddFourNumbers(1, 2);
 *      const g = f(3);
 *      g(4); //=> 10
 */
var curryN = _curry2(function curryN(length, fn) {
  if (length === 1) {
    return _curry1(fn);
  }
  return _arity(length, _curryN(length, [], fn));
});

/**
 * Creates a new list iteration function from an existing one by adding two new
 * parameters to its callback function: the current index, and the entire list.
 *
 * This would turn, for instance, [`R.map`](#map) function into one that
 * more closely resembles `Array.prototype.map`. Note that this will only work
 * for functions in which the iteration callback function is the first
 * parameter, and where the list is the last parameter. (This latter might be
 * unimportant if the list parameter is not used.)
 *
 * @func
 * @memberOf R
 * @since v0.15.0
 * @category Function
 * @category List
 * @sig ((a ... -> b) ... -> [a] -> *) -> ((a ..., Int, [a] -> b) ... -> [a] -> *)
 * @param {Function} fn A list iteration function that does not pass index or list to its callback
 * @return {Function} An altered list iteration function that passes (item, index, list) to its callback
 * @example
 *
 *      const mapIndexed = R.addIndex(R.map);
 *      mapIndexed((val, idx) => idx + '-' + val, ['f', 'o', 'o', 'b', 'a', 'r']);
 *      //=> ['0-f', '1-o', '2-o', '3-b', '4-a', '5-r']
 */
var addIndex = _curry1(function addIndex(fn) {
  return curryN(fn.length, function() {
    var idx = 0;
    var origFn = arguments[0];
    var list = arguments[arguments.length - 1];
    var args = Array.prototype.slice.call(arguments, 0);
    args[0] = function() {
      var result = origFn.apply(this, _concat(arguments, [idx, list]));
      idx += 1;
      return result;
    };
    return fn.apply(this, args);
  });
});

/**
 * Optimized internal three-arity curry function.
 *
 * @private
 * @category Function
 * @param {Function} fn The function to curry.
 * @return {Function} The curried function.
 */
function _curry3(fn) {
  return function f3(a, b, c) {
    switch (arguments.length) {
      case 0:
        return f3;
      case 1:
        return _isPlaceholder(a) ? f3
             : _curry2(function(_b, _c) { return fn(a, _b, _c); });
      case 2:
        return _isPlaceholder(a) && _isPlaceholder(b) ? f3
             : _isPlaceholder(a) ? _curry2(function(_a, _c) { return fn(_a, b, _c); })
             : _isPlaceholder(b) ? _curry2(function(_b, _c) { return fn(a, _b, _c); })
             : _curry1(function(_c) { return fn(a, b, _c); });
      default:
        return _isPlaceholder(a) && _isPlaceholder(b) && _isPlaceholder(c) ? f3
             : _isPlaceholder(a) && _isPlaceholder(b) ? _curry2(function(_a, _b) { return fn(_a, _b, c); })
             : _isPlaceholder(a) && _isPlaceholder(c) ? _curry2(function(_a, _c) { return fn(_a, b, _c); })
             : _isPlaceholder(b) && _isPlaceholder(c) ? _curry2(function(_b, _c) { return fn(a, _b, _c); })
             : _isPlaceholder(a) ? _curry1(function(_a) { return fn(_a, b, c); })
             : _isPlaceholder(b) ? _curry1(function(_b) { return fn(a, _b, c); })
             : _isPlaceholder(c) ? _curry1(function(_c) { return fn(a, b, _c); })
             : fn(a, b, c);
    }
  };
}

/**
 * Applies a function to the value at the given index of an array, returning a
 * new copy of the array with the element at the given index replaced with the
 * result of the function application.
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category List
 * @sig Number -> (a -> a) -> [a] -> [a]
 * @param {Number} idx The index.
 * @param {Function} fn The function to apply.
 * @param {Array|Arguments} list An array-like object whose value
 *        at the supplied index will be replaced.
 * @return {Array} A copy of the supplied array-like object with
 *         the element at index `idx` replaced with the value
 *         returned by applying `fn` to the existing element.
 * @see R.update
 * @example
 *
 *      R.adjust(1, R.toUpper, ['a', 'b', 'c', 'd']);      //=> ['a', 'B', 'c', 'd']
 *      R.adjust(-1, R.toUpper, ['a', 'b', 'c', 'd']);     //=> ['a', 'b', 'c', 'D']
 * @symb R.adjust(-1, f, [a, b]) = [a, f(b)]
 * @symb R.adjust(0, f, [a, b]) = [f(a), b]
 */
var adjust = _curry3(function adjust(idx, fn, list) {
  if (idx >= list.length || idx < -list.length) {
    return list;
  }
  var start = idx < 0 ? list.length : 0;
  var _idx = start + idx;
  var _list = _concat(list);
  _list[_idx] = fn(list[_idx]);
  return _list;
});

/**
 * Tests whether or not an object is an array.
 *
 * @private
 * @param {*} val The object to test.
 * @return {Boolean} `true` if `val` is an array, `false` otherwise.
 * @example
 *
 *      _isArray([]); //=> true
 *      _isArray(null); //=> false
 *      _isArray({}); //=> false
 */
var _isArray = Array.isArray || function _isArray(val) {
  return (val != null &&
          val.length >= 0 &&
          Object.prototype.toString.call(val) === '[object Array]');
};

function _isTransformer(obj) {
  return obj != null && typeof obj['@@transducer/step'] === 'function';
}

/**
 * Returns a function that dispatches with different strategies based on the
 * object in list position (last argument). If it is an array, executes [fn].
 * Otherwise, if it has a function with one of the given method names, it will
 * execute that function (functor case). Otherwise, if it is a transformer,
 * uses transducer [xf] to return a new transformer (transducer case).
 * Otherwise, it will default to executing [fn].
 *
 * @private
 * @param {Array} methodNames properties to check for a custom implementation
 * @param {Function} xf transducer to initialize if object is transformer
 * @param {Function} fn default ramda implementation
 * @return {Function} A function that dispatches on object in list position
 */
function _dispatchable(methodNames, xf, fn) {
  return function() {
    if (arguments.length === 0) {
      return fn();
    }
    var args = Array.prototype.slice.call(arguments, 0);
    var obj = args.pop();
    if (!_isArray(obj)) {
      var idx = 0;
      while (idx < methodNames.length) {
        if (typeof obj[methodNames[idx]] === 'function') {
          return obj[methodNames[idx]].apply(obj, args);
        }
        idx += 1;
      }
      if (_isTransformer(obj)) {
        var transducer = xf.apply(null, args);
        return transducer(obj);
      }
    }
    return fn.apply(this, arguments);
  };
}

function _reduced(x) {
  return x && x['@@transducer/reduced'] ? x :
    {
      '@@transducer/value': x,
      '@@transducer/reduced': true
    };
}

var _xfBase = {
  init: function() {
    return this.xf['@@transducer/init']();
  },
  result: function(result) {
    return this.xf['@@transducer/result'](result);
  }
};

function XAll(f, xf) {
  this.xf = xf;
  this.f = f;
  this.all = true;
}
XAll.prototype['@@transducer/init'] = _xfBase.init;
XAll.prototype['@@transducer/result'] = function(result) {
  if (this.all) {
    result = this.xf['@@transducer/step'](result, true);
  }
  return this.xf['@@transducer/result'](result);
};
XAll.prototype['@@transducer/step'] = function(result, input) {
  if (!this.f(input)) {
    this.all = false;
    result = _reduced(this.xf['@@transducer/step'](result, false));
  }
  return result;
};

var _xall = _curry2(function _xall(f, xf) { return new XAll(f, xf); });

/**
 * Returns `true` if all elements of the list match the predicate, `false` if
 * there are any that don't.
 *
 * Dispatches to the `all` method of the second argument, if present.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig (a -> Boolean) -> [a] -> Boolean
 * @param {Function} fn The predicate function.
 * @param {Array} list The array to consider.
 * @return {Boolean} `true` if the predicate is satisfied by every element, `false`
 *         otherwise.
 * @see R.any, R.none, R.transduce
 * @example
 *
 *      const equals3 = R.equals(3);
 *      R.all(equals3)([3, 3, 3, 3]); //=> true
 *      R.all(equals3)([3, 3, 1, 3]); //=> false
 */
var all = _curry2(_dispatchable(['all'], _xall, function all(fn, list) {
  var idx = 0;
  while (idx < list.length) {
    if (!fn(list[idx])) {
      return false;
    }
    idx += 1;
  }
  return true;
}));

/**
 * Returns the larger of its two arguments.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig Ord a => a -> a -> a
 * @param {*} a
 * @param {*} b
 * @return {*}
 * @see R.maxBy, R.min
 * @example
 *
 *      R.max(789, 123); //=> 789
 *      R.max('a', 'b'); //=> 'b'
 */
var max = _curry2(function max(a, b) { return b > a ? b : a; });

function _map(fn, functor) {
  var idx = 0;
  var len = functor.length;
  var result = Array(len);
  while (idx < len) {
    result[idx] = fn(functor[idx]);
    idx += 1;
  }
  return result;
}

function _isString(x) {
  return Object.prototype.toString.call(x) === '[object String]';
}

/**
 * Tests whether or not an object is similar to an array.
 *
 * @private
 * @category Type
 * @category List
 * @sig * -> Boolean
 * @param {*} x The object to test.
 * @return {Boolean} `true` if `x` has a numeric length property and extreme indices defined; `false` otherwise.
 * @example
 *
 *      _isArrayLike([]); //=> true
 *      _isArrayLike(true); //=> false
 *      _isArrayLike({}); //=> false
 *      _isArrayLike({length: 10}); //=> false
 *      _isArrayLike({0: 'zero', 9: 'nine', length: 10}); //=> true
 */
var _isArrayLike = _curry1(function isArrayLike(x) {
  if (_isArray(x)) { return true; }
  if (!x) { return false; }
  if (typeof x !== 'object') { return false; }
  if (_isString(x)) { return false; }
  if (x.nodeType === 1) { return !!x.length; }
  if (x.length === 0) { return true; }
  if (x.length > 0) {
    return x.hasOwnProperty(0) && x.hasOwnProperty(x.length - 1);
  }
  return false;
});

function XWrap(fn) {
  this.f = fn;
}
XWrap.prototype['@@transducer/init'] = function() {
  throw new Error('init not implemented on XWrap');
};
XWrap.prototype['@@transducer/result'] = function(acc) { return acc; };
XWrap.prototype['@@transducer/step'] = function(acc, x) {
  return this.f(acc, x);
};

function _xwrap(fn) { return new XWrap(fn); }

/**
 * Creates a function that is bound to a context.
 * Note: `R.bind` does not provide the additional argument-binding capabilities of
 * [Function.prototype.bind](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind).
 *
 * @func
 * @memberOf R
 * @since v0.6.0
 * @category Function
 * @category Object
 * @sig (* -> *) -> {*} -> (* -> *)
 * @param {Function} fn The function to bind to context
 * @param {Object} thisObj The context to bind `fn` to
 * @return {Function} A function that will execute in the context of `thisObj`.
 * @see R.partial
 * @example
 *
 *      const log = R.bind(console.log, console);
 *      R.pipe(R.assoc('a', 2), R.tap(log), R.assoc('a', 3))({a: 1}); //=> {a: 3}
 *      // logs {a: 2}
 * @symb R.bind(f, o)(a, b) = f.call(o, a, b)
 */
var bind = _curry2(function bind(fn, thisObj) {
  return _arity(fn.length, function() {
    return fn.apply(thisObj, arguments);
  });
});

function _arrayReduce(xf, acc, list) {
  var idx = 0;
  var len = list.length;
  while (idx < len) {
    acc = xf['@@transducer/step'](acc, list[idx]);
    if (acc && acc['@@transducer/reduced']) {
      acc = acc['@@transducer/value'];
      break;
    }
    idx += 1;
  }
  return xf['@@transducer/result'](acc);
}

function _iterableReduce(xf, acc, iter) {
  var step = iter.next();
  while (!step.done) {
    acc = xf['@@transducer/step'](acc, step.value);
    if (acc && acc['@@transducer/reduced']) {
      acc = acc['@@transducer/value'];
      break;
    }
    step = iter.next();
  }
  return xf['@@transducer/result'](acc);
}

function _methodReduce(xf, acc, obj, methodName) {
  return xf['@@transducer/result'](obj[methodName](bind(xf['@@transducer/step'], xf), acc));
}

var symIterator = (typeof Symbol !== 'undefined') ? Symbol.iterator : '@@iterator';

function _reduce(fn, acc, list) {
  if (typeof fn === 'function') {
    fn = _xwrap(fn);
  }
  if (_isArrayLike(list)) {
    return _arrayReduce(fn, acc, list);
  }
  if (typeof list['fantasy-land/reduce'] === 'function') {
    return _methodReduce(fn, acc, list, 'fantasy-land/reduce');
  }
  if (list[symIterator] != null) {
    return _iterableReduce(fn, acc, list[symIterator]());
  }
  if (typeof list.next === 'function') {
    return _iterableReduce(fn, acc, list);
  }
  if (typeof list.reduce === 'function') {
    return _methodReduce(fn, acc, list, 'reduce');
  }

  throw new TypeError('reduce: list must be array or iterable');
}

function XMap(f, xf) {
  this.xf = xf;
  this.f = f;
}
XMap.prototype['@@transducer/init'] = _xfBase.init;
XMap.prototype['@@transducer/result'] = _xfBase.result;
XMap.prototype['@@transducer/step'] = function(result, input) {
  return this.xf['@@transducer/step'](result, this.f(input));
};

var _xmap = _curry2(function _xmap(f, xf) { return new XMap(f, xf); });

function _has(prop, obj) {
  return Object.prototype.hasOwnProperty.call(obj, prop);
}

var toString = Object.prototype.toString;
var _isArguments = (function() {
  return toString.call(arguments) === '[object Arguments]' ?
    function _isArguments(x) { return toString.call(x) === '[object Arguments]'; } :
    function _isArguments(x) { return _has('callee', x); };
}());

// cover IE < 9 keys issues
var hasEnumBug = !({toString: null}).propertyIsEnumerable('toString');
var nonEnumerableProps = ['constructor', 'valueOf', 'isPrototypeOf', 'toString',
                          'propertyIsEnumerable', 'hasOwnProperty', 'toLocaleString'];
// Safari bug
var hasArgsEnumBug = (function() {
  'use strict';
  return arguments.propertyIsEnumerable('length');
}());

var contains = function contains(list, item) {
  var idx = 0;
  while (idx < list.length) {
    if (list[idx] === item) {
      return true;
    }
    idx += 1;
  }
  return false;
};

/**
 * Returns a list containing the names of all the enumerable own properties of
 * the supplied object.
 * Note that the order of the output array is not guaranteed to be consistent
 * across different JS platforms.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @sig {k: v} -> [k]
 * @param {Object} obj The object to extract properties from
 * @return {Array} An array of the object's own properties.
 * @see R.keysIn, R.values
 * @example
 *
 *      R.keys({a: 1, b: 2, c: 3}); //=> ['a', 'b', 'c']
 */
var keys = typeof Object.keys === 'function' && !hasArgsEnumBug ?
  _curry1(function keys(obj) {
    return Object(obj) !== obj ? [] : Object.keys(obj);
  }) :
  _curry1(function keys(obj) {
    if (Object(obj) !== obj) {
      return [];
    }
    var prop, nIdx;
    var ks = [];
    var checkArgsLength = hasArgsEnumBug && _isArguments(obj);
    for (prop in obj) {
      if (_has(prop, obj) && (!checkArgsLength || prop !== 'length')) {
        ks[ks.length] = prop;
      }
    }
    if (hasEnumBug) {
      nIdx = nonEnumerableProps.length - 1;
      while (nIdx >= 0) {
        prop = nonEnumerableProps[nIdx];
        if (_has(prop, obj) && !contains(ks, prop)) {
          ks[ks.length] = prop;
        }
        nIdx -= 1;
      }
    }
    return ks;
  });

/**
 * Takes a function and
 * a [functor](https://github.com/fantasyland/fantasy-land#functor),
 * applies the function to each of the functor's values, and returns
 * a functor of the same shape.
 *
 * Ramda provides suitable `map` implementations for `Array` and `Object`,
 * so this function may be applied to `[1, 2, 3]` or `{x: 1, y: 2, z: 3}`.
 *
 * Dispatches to the `map` method of the second argument, if present.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * Also treats functions as functors and will compose them together.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig Functor f => (a -> b) -> f a -> f b
 * @param {Function} fn The function to be called on every element of the input `list`.
 * @param {Array} list The list to be iterated over.
 * @return {Array} The new list.
 * @see R.transduce, R.addIndex
 * @example
 *
 *      const double = x => x * 2;
 *
 *      R.map(double, [1, 2, 3]); //=> [2, 4, 6]
 *
 *      R.map(double, {x: 1, y: 2, z: 3}); //=> {x: 2, y: 4, z: 6}
 * @symb R.map(f, [a, b]) = [f(a), f(b)]
 * @symb R.map(f, { x: a, y: b }) = { x: f(a), y: f(b) }
 * @symb R.map(f, functor_o) = functor_o.map(f)
 */
var map = _curry2(_dispatchable(['fantasy-land/map', 'map'], _xmap, function map(fn, functor) {
  switch (Object.prototype.toString.call(functor)) {
    case '[object Function]':
      return curryN(functor.length, function() {
        return fn.call(this, functor.apply(this, arguments));
      });
    case '[object Object]':
      return _reduce(function(acc, key) {
        acc[key] = fn(functor[key]);
        return acc;
      }, {}, keys(functor));
    default:
      return _map(fn, functor);
  }
}));

/**
 * Retrieve the value at a given path.
 *
 * @func
 * @memberOf R
 * @since v0.2.0
 * @category Object
 * @typedefn Idx = String | Int
 * @sig [Idx] -> {a} -> a | Undefined
 * @param {Array} path The path to use.
 * @param {Object} obj The object to retrieve the nested property from.
 * @return {*} The data at `path`.
 * @see R.prop
 * @example
 *
 *      R.path(['a', 'b'], {a: {b: 2}}); //=> 2
 *      R.path(['a', 'b'], {c: {b: 2}}); //=> undefined
 */
var path = _curry2(function path(paths, obj) {
  var val = obj;
  var idx = 0;
  while (idx < paths.length) {
    if (val == null) {
      return;
    }
    val = val[paths[idx]];
    idx += 1;
  }
  return val;
});

/**
 * Returns a function that when supplied an object returns the indicated
 * property of that object, if it exists.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @sig s -> {s: a} -> a | Undefined
 * @param {String} p The property name
 * @param {Object} obj The object to query
 * @return {*} The value at `obj.p`.
 * @see R.path
 * @example
 *
 *      R.prop('x', {x: 100}); //=> 100
 *      R.prop('x', {}); //=> undefined
 *      R.compose(R.inc, R.prop('x'))({ x: 3 }) //=> 4
 */

var prop = _curry2(function prop(p, obj) { return path([p], obj); });

/**
 * Returns a new list by plucking the same named property off all objects in
 * the list supplied.
 *
 * `pluck` will work on
 * any [functor](https://github.com/fantasyland/fantasy-land#functor) in
 * addition to arrays, as it is equivalent to `R.map(R.prop(k), f)`.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig Functor f => k -> f {k: v} -> f v
 * @param {Number|String} key The key name to pluck off of each object.
 * @param {Array} f The array or functor to consider.
 * @return {Array} The list of values for the given key.
 * @see R.props
 * @example
 *
 *      var getAges = R.pluck('age');
 *      getAges([{name: 'fred', age: 29}, {name: 'wilma', age: 27}]); //=> [29, 27]
 *
 *      R.pluck(0, [[1, 2], [3, 4]]);               //=> [1, 3]
 *      R.pluck('val', {a: {val: 3}, b: {val: 5}}); //=> {a: 3, b: 5}
 * @symb R.pluck('x', [{x: 1, y: 2}, {x: 3, y: 4}, {x: 5, y: 6}]) = [1, 3, 5]
 * @symb R.pluck(0, [[1, 2], [3, 4], [5, 6]]) = [1, 3, 5]
 */
var pluck = _curry2(function pluck(p, list) {
  return map(prop(p), list);
});

/**
 * Returns a single item by iterating through the list, successively calling
 * the iterator function and passing it an accumulator value and the current
 * value from the array, and then passing the result to the next call.
 *
 * The iterator function receives two values: *(acc, value)*. It may use
 * [`R.reduced`](#reduced) to shortcut the iteration.
 *
 * The arguments' order of [`reduceRight`](#reduceRight)'s iterator function
 * is *(value, acc)*.
 *
 * Note: `R.reduce` does not skip deleted or unassigned indices (sparse
 * arrays), unlike the native `Array.prototype.reduce` method. For more details
 * on this behavior, see:
 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce#Description
 *
 * Dispatches to the `reduce` method of the third argument, if present. When
 * doing so, it is up to the user to handle the [`R.reduced`](#reduced)
 * shortcuting, as this is not implemented by `reduce`.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig ((a, b) -> a) -> a -> [b] -> a
 * @param {Function} fn The iterator function. Receives two values, the accumulator and the
 *        current element from the array.
 * @param {*} acc The accumulator value.
 * @param {Array} list The list to iterate over.
 * @return {*} The final, accumulated value.
 * @see R.reduced, R.addIndex, R.reduceRight
 * @example
 *
 *      R.reduce(R.subtract, 0, [1, 2, 3, 4]) // => ((((0 - 1) - 2) - 3) - 4) = -10
 *      //          -               -10
 *      //         / \              / \
 *      //        -   4           -6   4
 *      //       / \              / \
 *      //      -   3   ==>     -3   3
 *      //     / \              / \
 *      //    -   2           -1   2
 *      //   / \              / \
 *      //  0   1            0   1
 *
 * @symb R.reduce(f, a, [b, c, d]) = f(f(f(a, b), c), d)
 */
var reduce = _curry3(_reduce);

/**
 * Takes a list of predicates and returns a predicate that returns true for a
 * given list of arguments if every one of the provided predicates is satisfied
 * by those arguments.
 *
 * The function returned is a curried function whose arity matches that of the
 * highest-arity predicate.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Logic
 * @sig [(*... -> Boolean)] -> (*... -> Boolean)
 * @param {Array} predicates An array of predicates to check
 * @return {Function} The combined predicate
 * @see R.anyPass
 * @example
 *
 *      const isQueen = R.propEq('rank', 'Q');
 *      const isSpade = R.propEq('suit', '♠︎');
 *      const isQueenOfSpades = R.allPass([isQueen, isSpade]);
 *
 *      isQueenOfSpades({rank: 'Q', suit: '♣︎'}); //=> false
 *      isQueenOfSpades({rank: 'Q', suit: '♠︎'}); //=> true
 */
var allPass = _curry1(function allPass(preds) {
  return curryN(reduce(max, 0, pluck('length', preds)), function() {
    var idx = 0;
    var len = preds.length;
    while (idx < len) {
      if (!preds[idx].apply(this, arguments)) {
        return false;
      }
      idx += 1;
    }
    return true;
  });
});

/**
 * Returns a function that always returns the given value. Note that for
 * non-primitives the value returned is a reference to the original value.
 *
 * This function is known as `const`, `constant`, or `K` (for K combinator) in
 * other languages and libraries.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig a -> (* -> a)
 * @param {*} val The value to wrap in a function
 * @return {Function} A Function :: * -> val.
 * @example
 *
 *      const t = R.always('Tee');
 *      t(); //=> 'Tee'
 */
var always = _curry1(function always(val) {
  return function() {
    return val;
  };
});

/**
 * Returns `true` if both arguments are `true`; `false` otherwise.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Logic
 * @sig a -> b -> a | b
 * @param {Any} a
 * @param {Any} b
 * @return {Any} the first argument if it is falsy, otherwise the second argument.
 * @see R.both
 * @example
 *
 *      R.and(true, true); //=> true
 *      R.and(true, false); //=> false
 *      R.and(false, true); //=> false
 *      R.and(false, false); //=> false
 */
var and = _curry2(function and(a, b) {
  return a && b;
});

function XAny(f, xf) {
  this.xf = xf;
  this.f = f;
  this.any = false;
}
XAny.prototype['@@transducer/init'] = _xfBase.init;
XAny.prototype['@@transducer/result'] = function(result) {
  if (!this.any) {
    result = this.xf['@@transducer/step'](result, false);
  }
  return this.xf['@@transducer/result'](result);
};
XAny.prototype['@@transducer/step'] = function(result, input) {
  if (this.f(input)) {
    this.any = true;
    result = _reduced(this.xf['@@transducer/step'](result, true));
  }
  return result;
};

var _xany = _curry2(function _xany(f, xf) { return new XAny(f, xf); });

/**
 * Returns `true` if at least one of the elements of the list match the predicate,
 * `false` otherwise.
 *
 * Dispatches to the `any` method of the second argument, if present.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig (a -> Boolean) -> [a] -> Boolean
 * @param {Function} fn The predicate function.
 * @param {Array} list The array to consider.
 * @return {Boolean} `true` if the predicate is satisfied by at least one element, `false`
 *         otherwise.
 * @see R.all, R.none, R.transduce
 * @example
 *
 *      const lessThan0 = R.flip(R.lt)(0);
 *      const lessThan2 = R.flip(R.lt)(2);
 *      R.any(lessThan0)([1, 2]); //=> false
 *      R.any(lessThan2)([1, 2]); //=> true
 */
var any = _curry2(_dispatchable(['any'], _xany, function any(fn, list) {
  var idx = 0;
  while (idx < list.length) {
    if (fn(list[idx])) {
      return true;
    }
    idx += 1;
  }
  return false;
}));

/**
 * Takes a list of predicates and returns a predicate that returns true for a
 * given list of arguments if at least one of the provided predicates is
 * satisfied by those arguments.
 *
 * The function returned is a curried function whose arity matches that of the
 * highest-arity predicate.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Logic
 * @sig [(*... -> Boolean)] -> (*... -> Boolean)
 * @param {Array} predicates An array of predicates to check
 * @return {Function} The combined predicate
 * @see R.allPass
 * @example
 *
 *      const isClub = R.propEq('suit', '♣');
 *      const isSpade = R.propEq('suit', '♠');
 *      const isBlackCard = R.anyPass([isClub, isSpade]);
 *
 *      isBlackCard({rank: '10', suit: '♣'}); //=> true
 *      isBlackCard({rank: 'Q', suit: '♠'}); //=> true
 *      isBlackCard({rank: 'Q', suit: '♦'}); //=> false
 */
var anyPass = _curry1(function anyPass(preds) {
  return curryN(reduce(max, 0, pluck('length', preds)), function() {
    var idx = 0;
    var len = preds.length;
    while (idx < len) {
      if (preds[idx].apply(this, arguments)) {
        return true;
      }
      idx += 1;
    }
    return false;
  });
});

/**
 * ap applies a list of functions to a list of values.
 *
 * Dispatches to the `ap` method of the second argument, if present. Also
 * treats curried functions as applicatives.
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category Function
 * @sig [a -> b] -> [a] -> [b]
 * @sig Apply f => f (a -> b) -> f a -> f b
 * @sig (r -> a -> b) -> (r -> a) -> (r -> b)
 * @param {*} applyF
 * @param {*} applyX
 * @return {*}
 * @example
 *
 *      R.ap([R.multiply(2), R.add(3)], [1,2,3]); //=> [2, 4, 6, 4, 5, 6]
 *      R.ap([R.concat('tasty '), R.toUpper], ['pizza', 'salad']); //=> ["tasty pizza", "tasty salad", "PIZZA", "SALAD"]
 *
 *      // R.ap can also be used as S combinator
 *      // when only two functions are passed
 *      R.ap(R.concat, R.toUpper)('Ramda') //=> 'RamdaRAMDA'
 * @symb R.ap([f, g], [a, b]) = [f(a), f(b), g(a), g(b)]
 */
var ap = _curry2(function ap(applyF, applyX) {
  return (
    typeof applyX['fantasy-land/ap'] === 'function' ?
      applyX['fantasy-land/ap'](applyF) :
    typeof applyF.ap === 'function' ?
      applyF.ap(applyX) :
    typeof applyF === 'function' ?
      function(x) { return applyF(x)(applyX(x)); } :
    // else
      _reduce(function(acc, f) { return _concat(acc, map(f, applyX)); }, [], applyF)
  );
});

function _aperture(n, list) {
  var idx = 0;
  var limit = list.length - (n - 1);
  var acc = new Array(limit >= 0 ? limit : 0);
  while (idx < limit) {
    acc[idx] = Array.prototype.slice.call(list, idx, idx + n);
    idx += 1;
  }
  return acc;
}

function XAperture(n, xf) {
  this.xf = xf;
  this.pos = 0;
  this.full = false;
  this.acc = new Array(n);
}
XAperture.prototype['@@transducer/init'] = _xfBase.init;
XAperture.prototype['@@transducer/result'] = function(result) {
  this.acc = null;
  return this.xf['@@transducer/result'](result);
};
XAperture.prototype['@@transducer/step'] = function(result, input) {
  this.store(input);
  return this.full ? this.xf['@@transducer/step'](result, this.getCopy()) : result;
};
XAperture.prototype.store = function(input) {
  this.acc[this.pos] = input;
  this.pos += 1;
  if (this.pos === this.acc.length) {
    this.pos = 0;
    this.full = true;
  }
};
XAperture.prototype.getCopy = function() {
  return _concat(Array.prototype.slice.call(this.acc, this.pos),
                 Array.prototype.slice.call(this.acc, 0, this.pos));
};

var _xaperture = _curry2(function _xaperture(n, xf) { return new XAperture(n, xf); });

/**
 * Returns a new list, composed of n-tuples of consecutive elements. If `n` is
 * greater than the length of the list, an empty list is returned.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.12.0
 * @category List
 * @sig Number -> [a] -> [[a]]
 * @param {Number} n The size of the tuples to create
 * @param {Array} list The list to split into `n`-length tuples
 * @return {Array} The resulting list of `n`-length tuples
 * @see R.transduce
 * @example
 *
 *      R.aperture(2, [1, 2, 3, 4, 5]); //=> [[1, 2], [2, 3], [3, 4], [4, 5]]
 *      R.aperture(3, [1, 2, 3, 4, 5]); //=> [[1, 2, 3], [2, 3, 4], [3, 4, 5]]
 *      R.aperture(7, [1, 2, 3, 4, 5]); //=> []
 */
var aperture = _curry2(_dispatchable([], _xaperture, _aperture));

/**
 * Returns a new list containing the contents of the given list, followed by
 * the given element.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig a -> [a] -> [a]
 * @param {*} el The element to add to the end of the new list.
 * @param {Array} list The list of elements to add a new item to.
 *        list.
 * @return {Array} A new list containing the elements of the old list followed by `el`.
 * @see R.prepend
 * @example
 *
 *      R.append('tests', ['write', 'more']); //=> ['write', 'more', 'tests']
 *      R.append('tests', []); //=> ['tests']
 *      R.append(['tests'], ['write', 'more']); //=> ['write', 'more', ['tests']]
 */
var append = _curry2(function append(el, list) {
  return _concat(list, [el]);
});

/**
 * Applies function `fn` to the argument list `args`. This is useful for
 * creating a fixed-arity function from a variadic function. `fn` should be a
 * bound function if context is significant.
 *
 * @func
 * @memberOf R
 * @since v0.7.0
 * @category Function
 * @sig (*... -> a) -> [*] -> a
 * @param {Function} fn The function which will be called with `args`
 * @param {Array} args The arguments to call `fn` with
 * @return {*} result The result, equivalent to `fn(...args)`
 * @see R.call, R.unapply
 * @example
 *
 *      const nums = [1, 2, 3, -99, 42, 6, 7];
 *      R.apply(Math.max, nums); //=> 42
 * @symb R.apply(f, [a, b, c]) = f(a, b, c)
 */
var apply = _curry2(function apply(fn, args) {
  return fn.apply(this, args);
});

/**
 * Returns a list of all the enumerable own properties of the supplied object.
 * Note that the order of the output array is not guaranteed across different
 * JS platforms.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @sig {k: v} -> [v]
 * @param {Object} obj The object to extract values from
 * @return {Array} An array of the values of the object's own properties.
 * @see R.valuesIn, R.keys
 * @example
 *
 *      R.values({a: 1, b: 2, c: 3}); //=> [1, 2, 3]
 */
var values = _curry1(function values(obj) {
  var props = keys(obj);
  var len = props.length;
  var vals = [];
  var idx = 0;
  while (idx < len) {
    vals[idx] = obj[props[idx]];
    idx += 1;
  }
  return vals;
});

// Use custom mapValues function to avoid issues with specs that include a "map" key and R.map
// delegating calls to .map
function mapValues(fn, obj) {
  return keys(obj).reduce(function(acc, key) {
    acc[key] = fn(obj[key]);
    return acc;
  }, {});
}

/**
 * Given a spec object recursively mapping properties to functions, creates a
 * function producing an object of the same structure, by mapping each property
 * to the result of calling its associated function with the supplied arguments.
 *
 * @func
 * @memberOf R
 * @since v0.20.0
 * @category Function
 * @sig {k: ((a, b, ..., m) -> v)} -> ((a, b, ..., m) -> {k: v})
 * @param {Object} spec an object recursively mapping properties to functions for
 *        producing the values for these properties.
 * @return {Function} A function that returns an object of the same structure
 * as `spec', with each property set to the value returned by calling its
 * associated function with the supplied arguments.
 * @see R.converge, R.juxt
 * @example
 *
 *      const getMetrics = R.applySpec({
 *        sum: R.add,
 *        nested: { mul: R.multiply }
 *      });
 *      getMetrics(2, 4); // => { sum: 6, nested: { mul: 8 } }
 * @symb R.applySpec({ x: f, y: { z: g } })(a, b) = { x: f(a, b), y: { z: g(a, b) } }
 */
var applySpec = _curry1(function applySpec(spec) {
  spec = mapValues(
    function(v) { return typeof v == 'function' ? v : applySpec(v); },
    spec
  );

  return curryN(
    reduce(max, 0, pluck('length', values(spec))),
    function() {
      var args = arguments;
      return mapValues(function(f) { return apply(f, args); }, spec);
    });
});

/**
 * Takes a value and applies a function to it.
 *
 * This function is also known as the `thrush` combinator.
 *
 * @func
 * @memberOf R
 * @since v0.25.0
 * @category Function
 * @sig a -> (a -> b) -> b
 * @param {*} x The value
 * @param {Function} f The function to apply
 * @return {*} The result of applying `f` to `x`
 * @example
 *
 *      const t42 = R.applyTo(42);
 *      t42(R.identity); //=> 42
 *      t42(R.add(1)); //=> 43
 */
var applyTo = _curry2(function applyTo(x, f) { return f(x); });

/**
 * Makes an ascending comparator function out of a function that returns a value
 * that can be compared with `<` and `>`.
 *
 * @func
 * @memberOf R
 * @since v0.23.0
 * @category Function
 * @sig Ord b => (a -> b) -> a -> a -> Number
 * @param {Function} fn A function of arity one that returns a value that can be compared
 * @param {*} a The first item to be compared.
 * @param {*} b The second item to be compared.
 * @return {Number} `-1` if fn(a) < fn(b), `1` if fn(b) < fn(a), otherwise `0`
 * @see R.descend
 * @example
 *
 *      const byAge = R.ascend(R.prop('age'));
 *      const people = [
 *        { name: 'Emma', age: 70 },
 *        { name: 'Peter', age: 78 },
 *        { name: 'Mikhail', age: 62 },
 *      ];
 *      const peopleByYoungestFirst = R.sort(byAge, people);
 *        //=> [{ name: 'Mikhail', age: 62 },{ name: 'Emma', age: 70 }, { name: 'Peter', age: 78 }]
 */
var ascend = _curry3(function ascend(fn, a, b) {
  var aa = fn(a);
  var bb = fn(b);
  return aa < bb ? -1 : aa > bb ? 1 : 0;
});

/**
 * Makes a shallow clone of an object, setting or overriding the specified
 * property with the given value. Note that this copies and flattens prototype
 * properties onto the new object as well. All non-primitive properties are
 * copied by reference.
 *
 * @func
 * @memberOf R
 * @since v0.8.0
 * @category Object
 * @sig String -> a -> {k: v} -> {k: v}
 * @param {String} prop The property name to set
 * @param {*} val The new value
 * @param {Object} obj The object to clone
 * @return {Object} A new object equivalent to the original except for the changed property.
 * @see R.dissoc, R.pick
 * @example
 *
 *      R.assoc('c', 3, {a: 1, b: 2}); //=> {a: 1, b: 2, c: 3}
 */
var assoc = _curry3(function assoc(prop, val, obj) {
  var result = {};
  for (var p in obj) {
    result[p] = obj[p];
  }
  result[prop] = val;
  return result;
});

/**
 * Determine if the passed argument is an integer.
 *
 * @private
 * @param {*} n
 * @category Type
 * @return {Boolean}
 */
var _isInteger = Number.isInteger || function _isInteger(n) {
  return (n << 0) === n;
};

/**
 * Checks if the input value is `null` or `undefined`.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Type
 * @sig * -> Boolean
 * @param {*} x The value to test.
 * @return {Boolean} `true` if `x` is `undefined` or `null`, otherwise `false`.
 * @example
 *
 *      R.isNil(null); //=> true
 *      R.isNil(undefined); //=> true
 *      R.isNil(0); //=> false
 *      R.isNil([]); //=> false
 */
var isNil = _curry1(function isNil(x) { return x == null; });

/**
 * Makes a shallow clone of an object, setting or overriding the nodes required
 * to create the given path, and placing the specific value at the tail end of
 * that path. Note that this copies and flattens prototype properties onto the
 * new object as well. All non-primitive properties are copied by reference.
 *
 * @func
 * @memberOf R
 * @since v0.8.0
 * @category Object
 * @typedefn Idx = String | Int
 * @sig [Idx] -> a -> {a} -> {a}
 * @param {Array} path the path to set
 * @param {*} val The new value
 * @param {Object} obj The object to clone
 * @return {Object} A new object equivalent to the original except along the specified path.
 * @see R.dissocPath
 * @example
 *
 *      R.assocPath(['a', 'b', 'c'], 42, {a: {b: {c: 0}}}); //=> {a: {b: {c: 42}}}
 *
 *      // Any missing or non-object keys in path will be overridden
 *      R.assocPath(['a', 'b', 'c'], 42, {a: 5}); //=> {a: {b: {c: 42}}}
 */
var assocPath = _curry3(function assocPath(path, val, obj) {
  if (path.length === 0) {
    return val;
  }
  var idx = path[0];
  if (path.length > 1) {
    var nextObj = (!isNil(obj) && _has(idx, obj)) ? obj[idx] : _isInteger(path[1]) ? [] : {};
    val = assocPath(Array.prototype.slice.call(path, 1), val, nextObj);
  }
  if (_isInteger(idx) && _isArray(obj)) {
    var arr = [].concat(obj);
    arr[idx] = val;
    return arr;
  } else {
    return assoc(idx, val, obj);
  }
});

/**
 * Wraps a function of any arity (including nullary) in a function that accepts
 * exactly `n` parameters. Any extraneous parameters will not be passed to the
 * supplied function.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig Number -> (* -> a) -> (* -> a)
 * @param {Number} n The desired arity of the new function.
 * @param {Function} fn The function to wrap.
 * @return {Function} A new function wrapping `fn`. The new function is guaranteed to be of
 *         arity `n`.
 * @see R.binary, R.unary
 * @example
 *
 *      const takesTwoArgs = (a, b) => [a, b];
 *
 *      takesTwoArgs.length; //=> 2
 *      takesTwoArgs(1, 2); //=> [1, 2]
 *
 *      const takesOneArg = R.nAry(1, takesTwoArgs);
 *      takesOneArg.length; //=> 1
 *      // Only `n` arguments are passed to the wrapped function
 *      takesOneArg(1, 2); //=> [1, undefined]
 * @symb R.nAry(0, f)(a, b) = f()
 * @symb R.nAry(1, f)(a, b) = f(a)
 * @symb R.nAry(2, f)(a, b) = f(a, b)
 */
var nAry = _curry2(function nAry(n, fn) {
  switch (n) {
    case 0: return function() {return fn.call(this);};
    case 1: return function(a0) {return fn.call(this, a0);};
    case 2: return function(a0, a1) {return fn.call(this, a0, a1);};
    case 3: return function(a0, a1, a2) {return fn.call(this, a0, a1, a2);};
    case 4: return function(a0, a1, a2, a3) {return fn.call(this, a0, a1, a2, a3);};
    case 5: return function(a0, a1, a2, a3, a4) {return fn.call(this, a0, a1, a2, a3, a4);};
    case 6: return function(a0, a1, a2, a3, a4, a5) {return fn.call(this, a0, a1, a2, a3, a4, a5);};
    case 7: return function(a0, a1, a2, a3, a4, a5, a6) {return fn.call(this, a0, a1, a2, a3, a4, a5, a6);};
    case 8: return function(a0, a1, a2, a3, a4, a5, a6, a7) {return fn.call(this, a0, a1, a2, a3, a4, a5, a6, a7);};
    case 9: return function(a0, a1, a2, a3, a4, a5, a6, a7, a8) {return fn.call(this, a0, a1, a2, a3, a4, a5, a6, a7, a8);};
    case 10: return function(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9) {return fn.call(this, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9);};
    default: throw new Error('First argument to nAry must be a non-negative integer no greater than ten');
  }
});

/**
 * Wraps a function of any arity (including nullary) in a function that accepts
 * exactly 2 parameters. Any extraneous parameters will not be passed to the
 * supplied function.
 *
 * @func
 * @memberOf R
 * @since v0.2.0
 * @category Function
 * @sig (* -> c) -> (a, b -> c)
 * @param {Function} fn The function to wrap.
 * @return {Function} A new function wrapping `fn`. The new function is guaranteed to be of
 *         arity 2.
 * @see R.nAry, R.unary
 * @example
 *
 *      const takesThreeArgs = function(a, b, c) {
 *        return [a, b, c];
 *      };
 *      takesThreeArgs.length; //=> 3
 *      takesThreeArgs(1, 2, 3); //=> [1, 2, 3]
 *
 *      const takesTwoArgs = R.binary(takesThreeArgs);
 *      takesTwoArgs.length; //=> 2
 *      // Only 2 arguments are passed to the wrapped function
 *      takesTwoArgs(1, 2, 3); //=> [1, 2, undefined]
 * @symb R.binary(f)(a, b, c) = f(a, b)
 */
var binary = _curry1(function binary(fn) {
  return nAry(2, fn);
});

function _isFunction(x) {
  return Object.prototype.toString.call(x) === '[object Function]';
}

/**
 * "lifts" a function to be the specified arity, so that it may "map over" that
 * many lists, Functions or other objects that satisfy the [FantasyLand Apply spec](https://github.com/fantasyland/fantasy-land#apply).
 *
 * @func
 * @memberOf R
 * @since v0.7.0
 * @category Function
 * @sig Number -> (*... -> *) -> ([*]... -> [*])
 * @param {Function} fn The function to lift into higher context
 * @return {Function} The lifted function.
 * @see R.lift, R.ap
 * @example
 *
 *      const madd3 = R.liftN(3, (...args) => R.sum(args));
 *      madd3([1,2,3], [1,2,3], [1]); //=> [3, 4, 5, 4, 5, 6, 5, 6, 7]
 */
var liftN = _curry2(function liftN(arity, fn) {
  var lifted = curryN(arity, fn);
  return curryN(arity, function() {
    return _reduce(ap, map(lifted, arguments[0]), Array.prototype.slice.call(arguments, 1));
  });
});

/**
 * "lifts" a function of arity > 1 so that it may "map over" a list, Function or other
 * object that satisfies the [FantasyLand Apply spec](https://github.com/fantasyland/fantasy-land#apply).
 *
 * @func
 * @memberOf R
 * @since v0.7.0
 * @category Function
 * @sig (*... -> *) -> ([*]... -> [*])
 * @param {Function} fn The function to lift into higher context
 * @return {Function} The lifted function.
 * @see R.liftN
 * @example
 *
 *      const madd3 = R.lift((a, b, c) => a + b + c);
 *
 *      madd3([1,2,3], [1,2,3], [1]); //=> [3, 4, 5, 4, 5, 6, 5, 6, 7]
 *
 *      const madd5 = R.lift((a, b, c, d, e) => a + b + c + d + e);
 *
 *      madd5([1,2], [3], [4, 5], [6], [7, 8]); //=> [21, 22, 22, 23, 22, 23, 23, 24]
 */
var lift = _curry1(function lift(fn) {
  return liftN(fn.length, fn);
});

/**
 * A function which calls the two provided functions and returns the `&&`
 * of the results.
 * It returns the result of the first function if it is false-y and the result
 * of the second function otherwise. Note that this is short-circuited,
 * meaning that the second function will not be invoked if the first returns a
 * false-y value.
 *
 * In addition to functions, `R.both` also accepts any fantasy-land compatible
 * applicative functor.
 *
 * @func
 * @memberOf R
 * @since v0.12.0
 * @category Logic
 * @sig (*... -> Boolean) -> (*... -> Boolean) -> (*... -> Boolean)
 * @param {Function} f A predicate
 * @param {Function} g Another predicate
 * @return {Function} a function that applies its arguments to `f` and `g` and `&&`s their outputs together.
 * @see R.and
 * @example
 *
 *      const gt10 = R.gt(R.__, 10)
 *      const lt20 = R.lt(R.__, 20)
 *      const f = R.both(gt10, lt20);
 *      f(15); //=> true
 *      f(30); //=> false
 *
 *      R.both(Maybe.Just(false), Maybe.Just(55)); // => Maybe.Just(false)
 *      R.both([false, false, 'a'], [11]); //=> [false, false, 11]
 */
var both = _curry2(function both(f, g) {
  return _isFunction(f) ?
    function _both() {
      return f.apply(this, arguments) && g.apply(this, arguments);
    } :
    lift(and)(f, g);
});

/**
 * Returns a curried equivalent of the provided function. The curried function
 * has two unusual capabilities. First, its arguments needn't be provided one
 * at a time. If `f` is a ternary function and `g` is `R.curry(f)`, the
 * following are equivalent:
 *
 *   - `g(1)(2)(3)`
 *   - `g(1)(2, 3)`
 *   - `g(1, 2)(3)`
 *   - `g(1, 2, 3)`
 *
 * Secondly, the special placeholder value [`R.__`](#__) may be used to specify
 * "gaps", allowing partial application of any combination of arguments,
 * regardless of their positions. If `g` is as above and `_` is [`R.__`](#__),
 * the following are equivalent:
 *
 *   - `g(1, 2, 3)`
 *   - `g(_, 2, 3)(1)`
 *   - `g(_, _, 3)(1)(2)`
 *   - `g(_, _, 3)(1, 2)`
 *   - `g(_, 2)(1)(3)`
 *   - `g(_, 2)(1, 3)`
 *   - `g(_, 2)(_, 3)(1)`
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig (* -> a) -> (* -> a)
 * @param {Function} fn The function to curry.
 * @return {Function} A new, curried function.
 * @see R.curryN, R.partial
 * @example
 *
 *      const addFourNumbers = (a, b, c, d) => a + b + c + d;
 *
 *      const curriedAddFourNumbers = R.curry(addFourNumbers);
 *      const f = curriedAddFourNumbers(1, 2);
 *      const g = f(3);
 *      g(4); //=> 10
 */
var curry = _curry1(function curry(fn) {
  return curryN(fn.length, fn);
});

/**
 * Returns the result of calling its first argument with the remaining
 * arguments. This is occasionally useful as a converging function for
 * [`R.converge`](#converge): the first branch can produce a function while the
 * remaining branches produce values to be passed to that function as its
 * arguments.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Function
 * @sig (*... -> a),*... -> a
 * @param {Function} fn The function to apply to the remaining arguments.
 * @param {...*} args Any number of positional arguments.
 * @return {*}
 * @see R.apply
 * @example
 *
 *      R.call(R.add, 1, 2); //=> 3
 *
 *      const indentN = R.pipe(R.repeat(' '),
 *                           R.join(''),
 *                           R.replace(/^(?!$)/gm));
 *
 *      const format = R.converge(R.call, [
 *                                  R.pipe(R.prop('indent'), indentN),
 *                                  R.prop('value')
 *                              ]);
 *
 *      format({indent: 2, value: 'foo\nbar\nbaz\n'}); //=> '  foo\n  bar\n  baz\n'
 * @symb R.call(f, a, b) = f(a, b)
 */
var call = curry(function call(fn) {
  return fn.apply(this, Array.prototype.slice.call(arguments, 1));
});

/**
 * `_makeFlat` is a helper function that returns a one-level or fully recursive
 * function based on the flag passed in.
 *
 * @private
 */
function _makeFlat(recursive) {
  return function flatt(list) {
    var value, jlen, j;
    var result = [];
    var idx = 0;
    var ilen = list.length;

    while (idx < ilen) {
      if (_isArrayLike(list[idx])) {
        value = recursive ? flatt(list[idx]) : list[idx];
        j = 0;
        jlen = value.length;
        while (j < jlen) {
          result[result.length] = value[j];
          j += 1;
        }
      } else {
        result[result.length] = list[idx];
      }
      idx += 1;
    }
    return result;
  };
}

function _forceReduced(x) {
  return {
    '@@transducer/value': x,
    '@@transducer/reduced': true
  };
}

var preservingReduced = function(xf) {
  return {
    '@@transducer/init': _xfBase.init,
    '@@transducer/result': function(result) {
      return xf['@@transducer/result'](result);
    },
    '@@transducer/step': function(result, input) {
      var ret = xf['@@transducer/step'](result, input);
      return ret['@@transducer/reduced'] ? _forceReduced(ret) : ret;
    }
  };
};

var _flatCat = function _xcat(xf) {
  var rxf = preservingReduced(xf);
  return {
    '@@transducer/init': _xfBase.init,
    '@@transducer/result': function(result) {
      return rxf['@@transducer/result'](result);
    },
    '@@transducer/step': function(result, input) {
      return !_isArrayLike(input) ? _reduce(rxf, result, [input]) : _reduce(rxf, result, input);
    }
  };
};

var _xchain = _curry2(function _xchain(f, xf) {
  return map(f, _flatCat(xf));
});

/**
 * `chain` maps a function over a list and concatenates the results. `chain`
 * is also known as `flatMap` in some libraries.
 *
 * Dispatches to the `chain` method of the second argument, if present,
 * according to the [FantasyLand Chain spec](https://github.com/fantasyland/fantasy-land#chain).
 *
 * If second argument is a function, `chain(f, g)(x)` is equivalent to `f(g(x), x)`.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category List
 * @sig Chain m => (a -> m b) -> m a -> m b
 * @param {Function} fn The function to map with
 * @param {Array} list The list to map over
 * @return {Array} The result of flat-mapping `list` with `fn`
 * @example
 *
 *      const duplicate = n => [n, n];
 *      R.chain(duplicate, [1, 2, 3]); //=> [1, 1, 2, 2, 3, 3]
 *
 *      R.chain(R.append, R.head)([1, 2, 3]); //=> [1, 2, 3, 1]
 */
var chain = _curry2(_dispatchable(['fantasy-land/chain', 'chain'], _xchain, function chain(fn, monad) {
  if (typeof monad === 'function') {
    return function(x) { return fn(monad(x))(x); };
  }
  return _makeFlat(false)(map(fn, monad));
}));

/**
 * Restricts a number to be within a range.
 *
 * Also works for other ordered types such as Strings and Dates.
 *
 * @func
 * @memberOf R
 * @since v0.20.0
 * @category Relation
 * @sig Ord a => a -> a -> a -> a
 * @param {Number} minimum The lower limit of the clamp (inclusive)
 * @param {Number} maximum The upper limit of the clamp (inclusive)
 * @param {Number} value Value to be clamped
 * @return {Number} Returns `minimum` when `val < minimum`, `maximum` when `val > maximum`, returns `val` otherwise
 * @example
 *
 *      R.clamp(1, 10, -5) // => 1
 *      R.clamp(1, 10, 15) // => 10
 *      R.clamp(1, 10, 4)  // => 4
 */
var clamp = _curry3(function clamp(min, max, value) {
  if (min > max) {
    throw new Error('min must not be greater than max in clamp(min, max, value)');
  }
  return value < min ? min :
         value > max ? max :
         value;
});

function _cloneRegExp(pattern) {
  return new RegExp(pattern.source, (pattern.global     ? 'g' : '') +
                                    (pattern.ignoreCase ? 'i' : '') +
                                    (pattern.multiline  ? 'm' : '') +
                                    (pattern.sticky     ? 'y' : '') +
                                    (pattern.unicode    ? 'u' : ''));
}

/**
 * Gives a single-word string description of the (native) type of a value,
 * returning such answers as 'Object', 'Number', 'Array', or 'Null'. Does not
 * attempt to distinguish user Object types any further, reporting them all as
 * 'Object'.
 *
 * @func
 * @memberOf R
 * @since v0.8.0
 * @category Type
 * @sig (* -> {*}) -> String
 * @param {*} val The value to test
 * @return {String}
 * @example
 *
 *      R.type({}); //=> "Object"
 *      R.type(1); //=> "Number"
 *      R.type(false); //=> "Boolean"
 *      R.type('s'); //=> "String"
 *      R.type(null); //=> "Null"
 *      R.type([]); //=> "Array"
 *      R.type(/[A-z]/); //=> "RegExp"
 *      R.type(() => {}); //=> "Function"
 *      R.type(undefined); //=> "Undefined"
 */
var type = _curry1(function type(val) {
  return val === null      ? 'Null'      :
         val === undefined ? 'Undefined' :
         Object.prototype.toString.call(val).slice(8, -1);
});

/**
 * Copies an object.
 *
 * @private
 * @param {*} value The value to be copied
 * @param {Array} refFrom Array containing the source references
 * @param {Array} refTo Array containing the copied source references
 * @param {Boolean} deep Whether or not to perform deep cloning.
 * @return {*} The copied value.
 */
function _clone(value, refFrom, refTo, deep) {
  var copy = function copy(copiedValue) {
    var len = refFrom.length;
    var idx = 0;
    while (idx < len) {
      if (value === refFrom[idx]) {
        return refTo[idx];
      }
      idx += 1;
    }
    refFrom[idx + 1] = value;
    refTo[idx + 1] = copiedValue;
    for (var key in value) {
      copiedValue[key] = deep ?
        _clone(value[key], refFrom, refTo, true) : value[key];
    }
    return copiedValue;
  };
  switch (type(value)) {
    case 'Object':  return copy({});
    case 'Array':   return copy([]);
    case 'Date':    return new Date(value.valueOf());
    case 'RegExp':  return _cloneRegExp(value);
    default:        return value;
  }
}

/**
 * Creates a deep copy of the value which may contain (nested) `Array`s and
 * `Object`s, `Number`s, `String`s, `Boolean`s and `Date`s. `Function`s are
 * assigned by reference rather than copied
 *
 * Dispatches to a `clone` method if present.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @sig {*} -> {*}
 * @param {*} value The object or array to clone
 * @return {*} A deeply cloned copy of `val`
 * @example
 *
 *      const objects = [{}, {}, {}];
 *      const objectsClone = R.clone(objects);
 *      objects === objectsClone; //=> false
 *      objects[0] === objectsClone[0]; //=> false
 */
var clone = _curry1(function clone(value) {
  return value != null && typeof value.clone === 'function' ?
    value.clone() :
    _clone(value, [], [], true);
});

/**
 * Makes a comparator function out of a function that reports whether the first
 * element is less than the second.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig ((a, b) -> Boolean) -> ((a, b) -> Number)
 * @param {Function} pred A predicate function of arity two which will return `true` if the first argument
 * is less than the second, `false` otherwise
 * @return {Function} A Function :: a -> b -> Int that returns `-1` if a < b, `1` if b < a, otherwise `0`
 * @example
 *
 *      const byAge = R.comparator((a, b) => a.age < b.age);
 *      const people = [
 *        { name: 'Emma', age: 70 },
 *        { name: 'Peter', age: 78 },
 *        { name: 'Mikhail', age: 62 },
 *      ];
 *      const peopleByIncreasingAge = R.sort(byAge, people);
 *        //=> [{ name: 'Mikhail', age: 62 },{ name: 'Emma', age: 70 }, { name: 'Peter', age: 78 }]
 */
var comparator = _curry1(function comparator(pred) {
  return function(a, b) {
    return pred(a, b) ? -1 : pred(b, a) ? 1 : 0;
  };
});

/**
 * A function that returns the `!` of its argument. It will return `true` when
 * passed false-y value, and `false` when passed a truth-y one.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Logic
 * @sig * -> Boolean
 * @param {*} a any value
 * @return {Boolean} the logical inverse of passed argument.
 * @see R.complement
 * @example
 *
 *      R.not(true); //=> false
 *      R.not(false); //=> true
 *      R.not(0); //=> true
 *      R.not(1); //=> false
 */
var not = _curry1(function not(a) {
  return !a;
});

/**
 * Takes a function `f` and returns a function `g` such that if called with the same arguments
 * when `f` returns a "truthy" value, `g` returns `false` and when `f` returns a "falsy" value `g` returns `true`.
 *
 * `R.complement` may be applied to any functor
 *
 * @func
 * @memberOf R
 * @since v0.12.0
 * @category Logic
 * @sig (*... -> *) -> (*... -> Boolean)
 * @param {Function} f
 * @return {Function}
 * @see R.not
 * @example
 *
 *      const isNotNil = R.complement(R.isNil);
 *      isNil(null); //=> true
 *      isNotNil(null); //=> false
 *      isNil(7); //=> false
 *      isNotNil(7); //=> true
 */
var complement = lift(not);

function _pipe(f, g) {
  return function() {
    return g.call(this, f.apply(this, arguments));
  };
}

/**
 * This checks whether a function has a [methodname] function. If it isn't an
 * array it will execute that function otherwise it will default to the ramda
 * implementation.
 *
 * @private
 * @param {Function} fn ramda implemtation
 * @param {String} methodname property to check for a custom implementation
 * @return {Object} Whatever the return value of the method is.
 */
function _checkForMethod(methodname, fn) {
  return function() {
    var length = arguments.length;
    if (length === 0) {
      return fn();
    }
    var obj = arguments[length - 1];
    return (_isArray(obj) || typeof obj[methodname] !== 'function') ?
      fn.apply(this, arguments) :
      obj[methodname].apply(obj, Array.prototype.slice.call(arguments, 0, length - 1));
  };
}

/**
 * Returns the elements of the given list or string (or object with a `slice`
 * method) from `fromIndex` (inclusive) to `toIndex` (exclusive).
 *
 * Dispatches to the `slice` method of the third argument, if present.
 *
 * @func
 * @memberOf R
 * @since v0.1.4
 * @category List
 * @sig Number -> Number -> [a] -> [a]
 * @sig Number -> Number -> String -> String
 * @param {Number} fromIndex The start index (inclusive).
 * @param {Number} toIndex The end index (exclusive).
 * @param {*} list
 * @return {*}
 * @example
 *
 *      R.slice(1, 3, ['a', 'b', 'c', 'd']);        //=> ['b', 'c']
 *      R.slice(1, Infinity, ['a', 'b', 'c', 'd']); //=> ['b', 'c', 'd']
 *      R.slice(0, -1, ['a', 'b', 'c', 'd']);       //=> ['a', 'b', 'c']
 *      R.slice(-3, -1, ['a', 'b', 'c', 'd']);      //=> ['b', 'c']
 *      R.slice(0, 3, 'ramda');                     //=> 'ram'
 */
var slice = _curry3(_checkForMethod('slice', function slice(fromIndex, toIndex, list) {
  return Array.prototype.slice.call(list, fromIndex, toIndex);
}));

/**
 * Returns all but the first element of the given list or string (or object
 * with a `tail` method).
 *
 * Dispatches to the `slice` method of the first argument, if present.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig [a] -> [a]
 * @sig String -> String
 * @param {*} list
 * @return {*}
 * @see R.head, R.init, R.last
 * @example
 *
 *      R.tail([1, 2, 3]);  //=> [2, 3]
 *      R.tail([1, 2]);     //=> [2]
 *      R.tail([1]);        //=> []
 *      R.tail([]);         //=> []
 *
 *      R.tail('abc');  //=> 'bc'
 *      R.tail('ab');   //=> 'b'
 *      R.tail('a');    //=> ''
 *      R.tail('');     //=> ''
 */
var tail = _curry1(_checkForMethod('tail', slice(1, Infinity)));

/**
 * Performs left-to-right function composition. The leftmost function may have
 * any arity; the remaining functions must be unary.
 *
 * In some libraries this function is named `sequence`.
 *
 * **Note:** The result of pipe is not automatically curried.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig (((a, b, ..., n) -> o), (o -> p), ..., (x -> y), (y -> z)) -> ((a, b, ..., n) -> z)
 * @param {...Function} functions
 * @return {Function}
 * @see R.compose
 * @example
 *
 *      const f = R.pipe(Math.pow, R.negate, R.inc);
 *
 *      f(3, 4); // -(3^4) + 1
 * @symb R.pipe(f, g, h)(a, b) = h(g(f(a, b)))
 */
function pipe() {
  if (arguments.length === 0) {
    throw new Error('pipe requires at least one argument');
  }
  return _arity(arguments[0].length,
                reduce(_pipe, arguments[0], tail(arguments)));
}

/**
 * Returns a new list or string with the elements or characters in reverse
 * order.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig [a] -> [a]
 * @sig String -> String
 * @param {Array|String} list
 * @return {Array|String}
 * @example
 *
 *      R.reverse([1, 2, 3]);  //=> [3, 2, 1]
 *      R.reverse([1, 2]);     //=> [2, 1]
 *      R.reverse([1]);        //=> [1]
 *      R.reverse([]);         //=> []
 *
 *      R.reverse('abc');      //=> 'cba'
 *      R.reverse('ab');       //=> 'ba'
 *      R.reverse('a');        //=> 'a'
 *      R.reverse('');         //=> ''
 */
var reverse = _curry1(function reverse(list) {
  return _isString(list) ? list.split('').reverse().join('') :
                           Array.prototype.slice.call(list, 0).reverse();
});

/**
 * Performs right-to-left function composition. The rightmost function may have
 * any arity; the remaining functions must be unary.
 *
 * **Note:** The result of compose is not automatically curried.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig ((y -> z), (x -> y), ..., (o -> p), ((a, b, ..., n) -> o)) -> ((a, b, ..., n) -> z)
 * @param {...Function} ...functions The functions to compose
 * @return {Function}
 * @see R.pipe
 * @example
 *
 *      const classyGreeting = (firstName, lastName) => "The name's " + lastName + ", " + firstName + " " + lastName
 *      const yellGreeting = R.compose(R.toUpper, classyGreeting);
 *      yellGreeting('James', 'Bond'); //=> "THE NAME'S BOND, JAMES BOND"
 *
 *      R.compose(Math.abs, R.add(1), R.multiply(2))(-4) //=> 7
 *
 * @symb R.compose(f, g, h)(a, b) = f(g(h(a, b)))
 */
function compose() {
  if (arguments.length === 0) {
    throw new Error('compose requires at least one argument');
  }
  return pipe.apply(this, reverse(arguments));
}

/**
 * Returns the right-to-left Kleisli composition of the provided functions,
 * each of which must return a value of a type supported by [`chain`](#chain).
 *
 * `R.composeK(h, g, f)` is equivalent to `R.compose(R.chain(h), R.chain(g), f)`.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category Function
 * @sig Chain m => ((y -> m z), (x -> m y), ..., (a -> m b)) -> (a -> m z)
 * @param {...Function} ...functions The functions to compose
 * @return {Function}
 * @see R.pipeK
 * @example
 *
 *       //  get :: String -> Object -> Maybe *
 *       const get = R.curry((propName, obj) => Maybe(obj[propName]))
 *
 *       //  getStateCode :: Maybe String -> Maybe String
 *       const getStateCode = R.composeK(
 *         R.compose(Maybe.of, R.toUpper),
 *         get('state'),
 *         get('address'),
 *         get('user'),
 *       );
 *       getStateCode({"user":{"address":{"state":"ny"}}}); //=> Maybe.Just("NY")
 *       getStateCode({}); //=> Maybe.Nothing()
 * @symb R.composeK(f, g, h)(a) = R.chain(f, R.chain(g, h(a)))
 */
function composeK() {
  if (arguments.length === 0) {
    throw new Error('composeK requires at least one argument');
  }
  var init = Array.prototype.slice.call(arguments);
  var last = init.pop();
  return compose(compose.apply(this, map(chain, init)), last);
}

function _pipeP(f, g) {
  return function() {
    var ctx = this;
    return f.apply(ctx, arguments).then(function(x) {
      return g.call(ctx, x);
    });
  };
}

/**
 * Performs left-to-right composition of one or more Promise-returning
 * functions. The leftmost function may have any arity; the remaining functions
 * must be unary.
 *
 * @func
 * @memberOf R
 * @since v0.10.0
 * @category Function
 * @sig ((a -> Promise b), (b -> Promise c), ..., (y -> Promise z)) -> (a -> Promise z)
 * @param {...Function} functions
 * @return {Function}
 * @see R.composeP
 * @example
 *
 *      //  followersForUser :: String -> Promise [User]
 *      const followersForUser = R.pipeP(db.getUserById, db.getFollowers);
 */
function pipeP() {
  if (arguments.length === 0) {
    throw new Error('pipeP requires at least one argument');
  }
  return _arity(arguments[0].length,
                reduce(_pipeP, arguments[0], tail(arguments)));
}

/**
 * Performs right-to-left composition of one or more Promise-returning
 * functions. The rightmost function may have any arity; the remaining
 * functions must be unary.
 *
 * @func
 * @memberOf R
 * @since v0.10.0
 * @category Function
 * @sig ((y -> Promise z), (x -> Promise y), ..., (a -> Promise b)) -> (a -> Promise z)
 * @param {...Function} functions The functions to compose
 * @return {Function}
 * @see R.pipeP
 * @example
 *
 *      const db = {
 *        users: {
 *          JOE: {
 *            name: 'Joe',
 *            followers: ['STEVE', 'SUZY']
 *          }
 *        }
 *      }
 *
 *      // We'll pretend to do a db lookup which returns a promise
 *      const lookupUser = (userId) => Promise.resolve(db.users[userId])
 *      const lookupFollowers = (user) => Promise.resolve(user.followers)
 *      lookupUser('JOE').then(lookupFollowers)
 *
 *      //  followersForUser :: String -> Promise [UserId]
 *      const followersForUser = R.composeP(lookupFollowers, lookupUser);
 *      followersForUser('JOE').then(followers => console.log('Followers:', followers))
 *      // Followers: ["STEVE","SUZY"]
 */
function composeP() {
  if (arguments.length === 0) {
    throw new Error('composeP requires at least one argument');
  }
  return pipeP.apply(this, reverse(arguments));
}

/**
 * Returns the nth element of the given list or string. If n is negative the
 * element at index length + n is returned.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig Number -> [a] -> a | Undefined
 * @sig Number -> String -> String
 * @param {Number} offset
 * @param {*} list
 * @return {*}
 * @example
 *
 *      const list = ['foo', 'bar', 'baz', 'quux'];
 *      R.nth(1, list); //=> 'bar'
 *      R.nth(-1, list); //=> 'quux'
 *      R.nth(-99, list); //=> undefined
 *
 *      R.nth(2, 'abc'); //=> 'c'
 *      R.nth(3, 'abc'); //=> ''
 * @symb R.nth(-1, [a, b, c]) = c
 * @symb R.nth(0, [a, b, c]) = a
 * @symb R.nth(1, [a, b, c]) = b
 */
var nth = _curry2(function nth(offset, list) {
  var idx = offset < 0 ? list.length + offset : offset;
  return _isString(list) ? list.charAt(idx) : list[idx];
});

/**
 * Returns the first element of the given list or string. In some libraries
 * this function is named `first`.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig [a] -> a | Undefined
 * @sig String -> String
 * @param {Array|String} list
 * @return {*}
 * @see R.tail, R.init, R.last
 * @example
 *
 *      R.head(['fi', 'fo', 'fum']); //=> 'fi'
 *      R.head([]); //=> undefined
 *
 *      R.head('abc'); //=> 'a'
 *      R.head(''); //=> ''
 */
var head = nth(0);

function _identity(x) { return x; }

/**
 * A function that does nothing but return the parameter supplied to it. Good
 * as a default or placeholder function.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig a -> a
 * @param {*} x The value to return.
 * @return {*} The input value, `x`.
 * @example
 *
 *      R.identity(1); //=> 1
 *
 *      const obj = {};
 *      R.identity(obj) === obj; //=> true
 * @symb R.identity(a) = a
 */
var identity = _curry1(_identity);

/**
 * Performs left-to-right function composition using transforming function. The leftmost function may have
 * any arity; the remaining functions must be unary.
 *
 * **Note:** The result of pipeWith is not automatically curried.
 *
 * @func
 * @memberOf R
 * @category Function
 * @sig ((* -> *), [((a, b, ..., n) -> o), (o -> p), ..., (x -> y), (y -> z)]) -> ((a, b, ..., n) -> z)
 * @param {...Function} functions
 * @return {Function}
 * @see R.composeWith, R.pipe
 * @example
 *
 *      const pipeWhileNotNil = R.pipeWith((f, res) => R.isNil(res) ? res : f(res));
 *      const f = pipeWhileNotNil([Math.pow, R.negate, R.inc])
 *
 *      f(3, 4); // -(3^4) + 1
 * @symb R.pipeWith(f)([g, h, i])(...args) = f(i, f(h, f(g, ...args)))
 */
var pipeWith = _curry2(function pipeWith(xf, list) {
  if (list.length <= 0) {
    return identity;
  }

  const headList = head(list);
  const tailList = tail(list);

  return _arity(headList.length, function() {
    return _reduce(
      function(result, f) {
        return xf.call(this, f, result);
      },
      headList.apply(this, arguments),
      tailList
    );
  });
});

/**
 * Performs right-to-left function composition using transforming function. The rightmost function may have
 * any arity; the remaining functions must be unary.
 *
 * **Note:** The result of compose is not automatically curried.
 *
 * @func
 * @memberOf R
 * @category Function
 * @sig ((* -> *), [(y -> z), (x -> y), ..., (o -> p), ((a, b, ..., n) -> o)]) -> ((a, b, ..., n) -> z)
 * @param {...Function} ...functions The functions to compose
 * @return {Function}
 * @see R.compose, R.pipeWith
 * @example
 *
 *      const composeWhileNotNil = R.composeWith((f, res) => R.isNil(res) ? res : f(res));
 *
 *      composeWhileNotNil([R.inc, R.prop('age')])({age: 1}) //=> 2
 *      composeWhileNotNil([R.inc, R.prop('age')])({}) //=> null
 *
 * @symb R.composeWith(f)([g, h, i])(...args) = f(g, f(h, f(i, ...args)))
 */
var composeWith = _curry2(function composeWith(xf, list) {
  return pipeWith.apply(this, [xf, reverse(list)]);
});

function _arrayFromIterator(iter) {
  var list = [];
  var next;
  while (!(next = iter.next()).done) {
    list.push(next.value);
  }
  return list;
}

function _includesWith(pred, x, list) {
  var idx = 0;
  var len = list.length;

  while (idx < len) {
    if (pred(x, list[idx])) {
      return true;
    }
    idx += 1;
  }
  return false;
}

function _functionName(f) {
  // String(x => x) evaluates to "x => x", so the pattern may not match.
  var match = String(f).match(/^function (\w*)/);
  return match == null ? '' : match[1];
}

// Based on https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is
function _objectIs(a, b) {
  // SameValue algorithm
  if (a === b) { // Steps 1-5, 7-10
    // Steps 6.b-6.e: +0 != -0
    return a !== 0 || 1 / a === 1 / b;
  } else {
    // Step 6.a: NaN == NaN
    return a !== a && b !== b;
  }
}

var _objectIs$1 = typeof Object.is === 'function' ? Object.is : _objectIs;

/**
 * private _uniqContentEquals function.
 * That function is checking equality of 2 iterator contents with 2 assumptions
 * - iterators lengths are the same
 * - iterators values are unique
 *
 * false-positive result will be returned for comparision of, e.g.
 * - [1,2,3] and [1,2,3,4]
 * - [1,1,1] and [1,2,3]
 * */

function _uniqContentEquals(aIterator, bIterator, stackA, stackB) {
  var a = _arrayFromIterator(aIterator);
  var b = _arrayFromIterator(bIterator);

  function eq(_a, _b) {
    return _equals(_a, _b, stackA.slice(), stackB.slice());
  }

  // if *a* array contains any element that is not included in *b*
  return !_includesWith(function(b, aItem) {
    return !_includesWith(eq, aItem, b);
  }, b, a);
}

function _equals(a, b, stackA, stackB) {
  if (_objectIs$1(a, b)) {
    return true;
  }

  var typeA = type(a);

  if (typeA !== type(b)) {
    return false;
  }

  if (a == null || b == null) {
    return false;
  }

  if (typeof a['fantasy-land/equals'] === 'function' || typeof b['fantasy-land/equals'] === 'function') {
    return typeof a['fantasy-land/equals'] === 'function' && a['fantasy-land/equals'](b) &&
      typeof b['fantasy-land/equals'] === 'function' && b['fantasy-land/equals'](a);
  }

  if (typeof a.equals === 'function' || typeof b.equals === 'function') {
    return typeof a.equals === 'function' && a.equals(b) &&
      typeof b.equals === 'function' && b.equals(a);
  }

  switch (typeA) {
    case 'Arguments':
    case 'Array':
    case 'Object':
      if (typeof a.constructor === 'function' &&
        _functionName(a.constructor) === 'Promise') {
        return a === b;
      }
      break;
    case 'Boolean':
    case 'Number':
    case 'String':
      if (!(typeof a === typeof b && _objectIs$1(a.valueOf(), b.valueOf()))) {
        return false;
      }
      break;
    case 'Date':
      if (!_objectIs$1(a.valueOf(), b.valueOf())) {
        return false;
      }
      break;
    case 'Error':
      return a.name === b.name && a.message === b.message;
    case 'RegExp':
      if (!(a.source === b.source &&
          a.global === b.global &&
          a.ignoreCase === b.ignoreCase &&
          a.multiline === b.multiline &&
          a.sticky === b.sticky &&
          a.unicode === b.unicode)) {
        return false;
      }
      break;
  }

  var idx = stackA.length - 1;
  while (idx >= 0) {
    if (stackA[idx] === a) {
      return stackB[idx] === b;
    }
    idx -= 1;
  }

  switch (typeA) {
    case 'Map':
      if (a.size !== b.size) {
        return false;
      }

      return _uniqContentEquals(a.entries(), b.entries(), stackA.concat([a]), stackB.concat([b]));
    case 'Set':
      if (a.size !== b.size) {
        return false;
      }

      return _uniqContentEquals(a.values(), b.values(), stackA.concat([a]), stackB.concat([b]));
    case 'Arguments':
    case 'Array':
    case 'Object':
    case 'Boolean':
    case 'Number':
    case 'String':
    case 'Date':
    case 'Error':
    case 'RegExp':
    case 'Int8Array':
    case 'Uint8Array':
    case 'Uint8ClampedArray':
    case 'Int16Array':
    case 'Uint16Array':
    case 'Int32Array':
    case 'Uint32Array':
    case 'Float32Array':
    case 'Float64Array':
    case 'ArrayBuffer':
      break;
    default:
      // Values of other types are only equal if identical.
      return false;
  }

  var keysA = keys(a);
  if (keysA.length !== keys(b).length) {
    return false;
  }

  var extendedStackA = stackA.concat([a]);
  var extendedStackB = stackB.concat([b]);

  idx = keysA.length - 1;
  while (idx >= 0) {
    var key = keysA[idx];
    if (!(_has(key, b) && _equals(b[key], a[key], extendedStackA, extendedStackB))) {
      return false;
    }
    idx -= 1;
  }
  return true;
}

/**
 * Returns `true` if its arguments are equivalent, `false` otherwise. Handles
 * cyclical data structures.
 *
 * Dispatches symmetrically to the `equals` methods of both arguments, if
 * present.
 *
 * @func
 * @memberOf R
 * @since v0.15.0
 * @category Relation
 * @sig a -> b -> Boolean
 * @param {*} a
 * @param {*} b
 * @return {Boolean}
 * @example
 *
 *      R.equals(1, 1); //=> true
 *      R.equals(1, '1'); //=> false
 *      R.equals([1, 2, 3], [1, 2, 3]); //=> true
 *
 *      const a = {}; a.v = a;
 *      const b = {}; b.v = b;
 *      R.equals(a, b); //=> true
 */
var equals = _curry2(function equals(a, b) {
  return _equals(a, b, [], []);
});

function _indexOf(list, a, idx) {
  var inf, item;
  // Array.prototype.indexOf doesn't exist below IE9
  if (typeof list.indexOf === 'function') {
    switch (typeof a) {
      case 'number':
        if (a === 0) {
          // manually crawl the list to distinguish between +0 and -0
          inf = 1 / a;
          while (idx < list.length) {
            item = list[idx];
            if (item === 0 && 1 / item === inf) {
              return idx;
            }
            idx += 1;
          }
          return -1;
        } else if (a !== a) {
          // NaN
          while (idx < list.length) {
            item = list[idx];
            if (typeof item === 'number' && item !== item) {
              return idx;
            }
            idx += 1;
          }
          return -1;
        }
        // non-zero numbers can utilise Set
        return list.indexOf(a, idx);

      // all these types can utilise Set
      case 'string':
      case 'boolean':
      case 'function':
      case 'undefined':
        return list.indexOf(a, idx);

      case 'object':
        if (a === null) {
          // null can utilise Set
          return list.indexOf(a, idx);
        }
    }
  }
  // anything else not covered above, defer to R.equals
  while (idx < list.length) {
    if (equals(list[idx], a)) {
      return idx;
    }
    idx += 1;
  }
  return -1;
}

function _includes(a, list) {
  return _indexOf(list, a, 0) >= 0;
}

function _quote(s) {
  var escaped = s
    .replace(/\\/g, '\\\\')
    .replace(/[\b]/g, '\\b')  // \b matches word boundary; [\b] matches backspace
    .replace(/\f/g, '\\f')
    .replace(/\n/g, '\\n')
    .replace(/\r/g, '\\r')
    .replace(/\t/g, '\\t')
    .replace(/\v/g, '\\v')
    .replace(/\0/g, '\\0');

  return '"' + escaped.replace(/"/g, '\\"') + '"';
}

/**
 * Polyfill from <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toISOString>.
 */
var pad = function pad(n) { return (n < 10 ? '0' : '') + n; };

var _toISOString = typeof Date.prototype.toISOString === 'function' ?
  function _toISOString(d) {
    return d.toISOString();
  } :
  function _toISOString(d) {
    return (
      d.getUTCFullYear() + '-' +
      pad(d.getUTCMonth() + 1) + '-' +
      pad(d.getUTCDate()) + 'T' +
      pad(d.getUTCHours()) + ':' +
      pad(d.getUTCMinutes()) + ':' +
      pad(d.getUTCSeconds()) + '.' +
      (d.getUTCMilliseconds() / 1000).toFixed(3).slice(2, 5) + 'Z'
    );
  };

function _complement(f) {
  return function() {
    return !f.apply(this, arguments);
  };
}

function _filter(fn, list) {
  var idx = 0;
  var len = list.length;
  var result = [];

  while (idx < len) {
    if (fn(list[idx])) {
      result[result.length] = list[idx];
    }
    idx += 1;
  }
  return result;
}

function _isObject(x) {
  return Object.prototype.toString.call(x) === '[object Object]';
}

function XFilter(f, xf) {
  this.xf = xf;
  this.f = f;
}
XFilter.prototype['@@transducer/init'] = _xfBase.init;
XFilter.prototype['@@transducer/result'] = _xfBase.result;
XFilter.prototype['@@transducer/step'] = function(result, input) {
  return this.f(input) ? this.xf['@@transducer/step'](result, input) : result;
};

var _xfilter = _curry2(function _xfilter(f, xf) { return new XFilter(f, xf); });

/**
 * Takes a predicate and a `Filterable`, and returns a new filterable of the
 * same type containing the members of the given filterable which satisfy the
 * given predicate. Filterable objects include plain objects or any object
 * that has a filter method such as `Array`.
 *
 * Dispatches to the `filter` method of the second argument, if present.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig Filterable f => (a -> Boolean) -> f a -> f a
 * @param {Function} pred
 * @param {Array} filterable
 * @return {Array} Filterable
 * @see R.reject, R.transduce, R.addIndex
 * @example
 *
 *      const isEven = n => n % 2 === 0;
 *
 *      R.filter(isEven, [1, 2, 3, 4]); //=> [2, 4]
 *
 *      R.filter(isEven, {a: 1, b: 2, c: 3, d: 4}); //=> {b: 2, d: 4}
 */
var filter = _curry2(_dispatchable(['filter'], _xfilter, function(pred, filterable) {
  return (
    _isObject(filterable) ?
      _reduce(function(acc, key) {
        if (pred(filterable[key])) {
          acc[key] = filterable[key];
        }
        return acc;
      }, {}, keys(filterable)) :
    // else
      _filter(pred, filterable)
  );
}));

/**
 * The complement of [`filter`](#filter).
 *
 * Acts as a transducer if a transformer is given in list position. Filterable
 * objects include plain objects or any object that has a filter method such
 * as `Array`.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig Filterable f => (a -> Boolean) -> f a -> f a
 * @param {Function} pred
 * @param {Array} filterable
 * @return {Array}
 * @see R.filter, R.transduce, R.addIndex
 * @example
 *
 *      const isOdd = (n) => n % 2 === 1;
 *
 *      R.reject(isOdd, [1, 2, 3, 4]); //=> [2, 4]
 *
 *      R.reject(isOdd, {a: 1, b: 2, c: 3, d: 4}); //=> {b: 2, d: 4}
 */
var reject = _curry2(function reject(pred, filterable) {
  return filter(_complement(pred), filterable);
});

function _toString(x, seen) {
  var recur = function recur(y) {
    var xs = seen.concat([x]);
    return _includes(y, xs) ? '<Circular>' : _toString(y, xs);
  };

  //  mapPairs :: (Object, [String]) -> [String]
  var mapPairs = function(obj, keys$$1) {
    return _map(function(k) { return _quote(k) + ': ' + recur(obj[k]); }, keys$$1.slice().sort());
  };

  switch (Object.prototype.toString.call(x)) {
    case '[object Arguments]':
      return '(function() { return arguments; }(' + _map(recur, x).join(', ') + '))';
    case '[object Array]':
      return '[' + _map(recur, x).concat(mapPairs(x, reject(function(k) { return /^\d+$/.test(k); }, keys(x)))).join(', ') + ']';
    case '[object Boolean]':
      return typeof x === 'object' ? 'new Boolean(' + recur(x.valueOf()) + ')' : x.toString();
    case '[object Date]':
      return 'new Date(' + (isNaN(x.valueOf()) ? recur(NaN) : _quote(_toISOString(x))) + ')';
    case '[object Null]':
      return 'null';
    case '[object Number]':
      return typeof x === 'object' ? 'new Number(' + recur(x.valueOf()) + ')' : 1 / x === -Infinity ? '-0' : x.toString(10);
    case '[object String]':
      return typeof x === 'object' ? 'new String(' + recur(x.valueOf()) + ')' : _quote(x);
    case '[object Undefined]':
      return 'undefined';
    default:
      if (typeof x.toString === 'function') {
        var repr = x.toString();
        if (repr !== '[object Object]') {
          return repr;
        }
      }
      return '{' + mapPairs(x, keys(x)).join(', ') + '}';
  }
}

/**
 * Returns the string representation of the given value. `eval`'ing the output
 * should result in a value equivalent to the input value. Many of the built-in
 * `toString` methods do not satisfy this requirement.
 *
 * If the given value is an `[object Object]` with a `toString` method other
 * than `Object.prototype.toString`, this method is invoked with no arguments
 * to produce the return value. This means user-defined constructor functions
 * can provide a suitable `toString` method. For example:
 *
 *     function Point(x, y) {
 *       this.x = x;
 *       this.y = y;
 *     }
 *
 *     Point.prototype.toString = function() {
 *       return 'new Point(' + this.x + ', ' + this.y + ')';
 *     };
 *
 *     R.toString(new Point(1, 2)); //=> 'new Point(1, 2)'
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category String
 * @sig * -> String
 * @param {*} val
 * @return {String}
 * @example
 *
 *      R.toString(42); //=> '42'
 *      R.toString('abc'); //=> '"abc"'
 *      R.toString([1, 2, 3]); //=> '[1, 2, 3]'
 *      R.toString({foo: 1, bar: 2, baz: 3}); //=> '{"bar": 2, "baz": 3, "foo": 1}'
 *      R.toString(new Date('2001-02-03T04:05:06Z')); //=> 'new Date("2001-02-03T04:05:06.000Z")'
 */
var toString$1 = _curry1(function toString(val) { return _toString(val, []); });

/**
 * Returns the result of concatenating the given lists or strings.
 *
 * Note: `R.concat` expects both arguments to be of the same type,
 * unlike the native `Array.prototype.concat` method. It will throw
 * an error if you `concat` an Array with a non-Array value.
 *
 * Dispatches to the `concat` method of the first argument, if present.
 * Can also concatenate two members of a [fantasy-land
 * compatible semigroup](https://github.com/fantasyland/fantasy-land#semigroup).
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig [a] -> [a] -> [a]
 * @sig String -> String -> String
 * @param {Array|String} firstList The first list
 * @param {Array|String} secondList The second list
 * @return {Array|String} A list consisting of the elements of `firstList` followed by the elements of
 * `secondList`.
 *
 * @example
 *
 *      R.concat('ABC', 'DEF'); // 'ABCDEF'
 *      R.concat([4, 5, 6], [1, 2, 3]); //=> [4, 5, 6, 1, 2, 3]
 *      R.concat([], []); //=> []
 */
var concat = _curry2(function concat(a, b) {
  if (_isArray(a)) {
    if (_isArray(b)) {
      return a.concat(b);
    }
    throw new TypeError(toString$1(b) + ' is not an array');
  }
  if (_isString(a)) {
    if (_isString(b)) {
      return a + b;
    }
    throw new TypeError(toString$1(b) + ' is not a string');
  }
  if (a != null && _isFunction(a['fantasy-land/concat'])) {
    return a['fantasy-land/concat'](b);
  }
  if (a != null && _isFunction(a.concat)) {
    return a.concat(b);
  }
  throw new TypeError(toString$1(a) + ' does not have a method named "concat" or "fantasy-land/concat"');
});

/**
 * Returns a function, `fn`, which encapsulates `if/else, if/else, ...` logic.
 * `R.cond` takes a list of [predicate, transformer] pairs. All of the arguments
 * to `fn` are applied to each of the predicates in turn until one returns a
 * "truthy" value, at which point `fn` returns the result of applying its
 * arguments to the corresponding transformer. If none of the predicates
 * matches, `fn` returns undefined.
 *
 * @func
 * @memberOf R
 * @since v0.6.0
 * @category Logic
 * @sig [[(*... -> Boolean),(*... -> *)]] -> (*... -> *)
 * @param {Array} pairs A list of [predicate, transformer]
 * @return {Function}
 * @see R.ifElse, R.unless, R.when
 * @example
 *
 *      const fn = R.cond([
 *        [R.equals(0),   R.always('water freezes at 0°C')],
 *        [R.equals(100), R.always('water boils at 100°C')],
 *        [R.T,           temp => 'nothing special happens at ' + temp + '°C']
 *      ]);
 *      fn(0); //=> 'water freezes at 0°C'
 *      fn(50); //=> 'nothing special happens at 50°C'
 *      fn(100); //=> 'water boils at 100°C'
 */
var cond = _curry1(function cond(pairs) {
  var arity = reduce(max,
                     0,
                     map(function(pair) { return pair[0].length; }, pairs));
  return _arity(arity, function() {
    var idx = 0;
    while (idx < pairs.length) {
      if (pairs[idx][0].apply(this, arguments)) {
        return pairs[idx][1].apply(this, arguments);
      }
      idx += 1;
    }
  });
});

/**
 * Wraps a constructor function inside a curried function that can be called
 * with the same arguments and returns the same type. The arity of the function
 * returned is specified to allow using variadic constructor functions.
 *
 * @func
 * @memberOf R
 * @since v0.4.0
 * @category Function
 * @sig Number -> (* -> {*}) -> (* -> {*})
 * @param {Number} n The arity of the constructor function.
 * @param {Function} Fn The constructor function to wrap.
 * @return {Function} A wrapped, curried constructor function.
 * @example
 *
 *      // Variadic Constructor function
 *      function Salad() {
 *        this.ingredients = arguments;
 *      }
 *
 *      Salad.prototype.recipe = function() {
 *        const instructions = R.map(ingredient => 'Add a dollop of ' + ingredient, this.ingredients);
 *        return R.join('\n', instructions);
 *      };
 *
 *      const ThreeLayerSalad = R.constructN(3, Salad);
 *
 *      // Notice we no longer need the 'new' keyword, and the constructor is curried for 3 arguments.
 *      const salad = ThreeLayerSalad('Mayonnaise')('Potato Chips')('Ketchup');
 *
 *      console.log(salad.recipe());
 *      // Add a dollop of Mayonnaise
 *      // Add a dollop of Potato Chips
 *      // Add a dollop of Ketchup
 */
var constructN = _curry2(function constructN(n, Fn) {
  if (n > 10) {
    throw new Error('Constructor with greater than ten arguments');
  }
  if (n === 0) {
    return function() { return new Fn(); };
  }
  return curry(nAry(n, function($0, $1, $2, $3, $4, $5, $6, $7, $8, $9) {
    switch (arguments.length) {
      case  1: return new Fn($0);
      case  2: return new Fn($0, $1);
      case  3: return new Fn($0, $1, $2);
      case  4: return new Fn($0, $1, $2, $3);
      case  5: return new Fn($0, $1, $2, $3, $4);
      case  6: return new Fn($0, $1, $2, $3, $4, $5);
      case  7: return new Fn($0, $1, $2, $3, $4, $5, $6);
      case  8: return new Fn($0, $1, $2, $3, $4, $5, $6, $7);
      case  9: return new Fn($0, $1, $2, $3, $4, $5, $6, $7, $8);
      case 10: return new Fn($0, $1, $2, $3, $4, $5, $6, $7, $8, $9);
    }
  }));
});

/**
 * Wraps a constructor function inside a curried function that can be called
 * with the same arguments and returns the same type.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig (* -> {*}) -> (* -> {*})
 * @param {Function} fn The constructor function to wrap.
 * @return {Function} A wrapped, curried constructor function.
 * @see R.invoker
 * @example
 *
 *      // Constructor function
 *      function Animal(kind) {
 *        this.kind = kind;
 *      };
 *      Animal.prototype.sighting = function() {
 *        return "It's a " + this.kind + "!";
 *      }
 *
 *      const AnimalConstructor = R.construct(Animal)
 *
 *      // Notice we no longer need the 'new' keyword:
 *      AnimalConstructor('Pig'); //=> {"kind": "Pig", "sighting": function (){...}};
 *
 *      const animalTypes = ["Lion", "Tiger", "Bear"];
 *      const animalSighting = R.invoker(0, 'sighting');
 *      const sightNewAnimal = R.compose(animalSighting, AnimalConstructor);
 *      R.map(sightNewAnimal, animalTypes); //=> ["It's a Lion!", "It's a Tiger!", "It's a Bear!"]
 */
var construct = _curry1(function construct(Fn) {
  return constructN(Fn.length, Fn);
});

/**
 * Returns `true` if the specified value is equal, in [`R.equals`](#equals)
 * terms, to at least one element of the given list; `false` otherwise.
 * Works also with strings.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig a -> [a] -> Boolean
 * @param {Object} a The item to compare against.
 * @param {Array} list The array to consider.
 * @return {Boolean} `true` if an equivalent item is in the list, `false` otherwise.
 * @see R.includes
 * @deprecated since v0.26.0
 * @example
 *
 *      R.contains(3, [1, 2, 3]); //=> true
 *      R.contains(4, [1, 2, 3]); //=> false
 *      R.contains({ name: 'Fred' }, [{ name: 'Fred' }]); //=> true
 *      R.contains([42], [[42]]); //=> true
 *      R.contains('ba', 'banana'); //=>true
 */
var contains$1 = _curry2(_includes);

/**
 * Accepts a converging function and a list of branching functions and returns
 * a new function. The arity of the new function is the same as the arity of
 * the longest branching function. When invoked, this new function is applied
 * to some arguments, and each branching function is applied to those same
 * arguments. The results of each branching function are passed as arguments
 * to the converging function to produce the return value.
 *
 * @func
 * @memberOf R
 * @since v0.4.2
 * @category Function
 * @sig ((x1, x2, ...) -> z) -> [((a, b, ...) -> x1), ((a, b, ...) -> x2), ...] -> (a -> b -> ... -> z)
 * @param {Function} after A function. `after` will be invoked with the return values of
 *        `fn1` and `fn2` as its arguments.
 * @param {Array} functions A list of functions.
 * @return {Function} A new function.
 * @see R.useWith
 * @example
 *
 *      const average = R.converge(R.divide, [R.sum, R.length])
 *      average([1, 2, 3, 4, 5, 6, 7]) //=> 4
 *
 *      const strangeConcat = R.converge(R.concat, [R.toUpper, R.toLower])
 *      strangeConcat("Yodel") //=> "YODELyodel"
 *
 * @symb R.converge(f, [g, h])(a, b) = f(g(a, b), h(a, b))
 */
var converge = _curry2(function converge(after, fns) {
  return curryN(reduce(max, 0, pluck('length', fns)), function() {
    var args = arguments;
    var context = this;
    return after.apply(context, _map(function(fn) {
      return fn.apply(context, args);
    }, fns));
  });
});

function XReduceBy(valueFn, valueAcc, keyFn, xf) {
  this.valueFn = valueFn;
  this.valueAcc = valueAcc;
  this.keyFn = keyFn;
  this.xf = xf;
  this.inputs = {};
}
XReduceBy.prototype['@@transducer/init'] = _xfBase.init;
XReduceBy.prototype['@@transducer/result'] = function(result) {
  var key;
  for (key in this.inputs) {
    if (_has(key, this.inputs)) {
      result = this.xf['@@transducer/step'](result, this.inputs[key]);
      if (result['@@transducer/reduced']) {
        result = result['@@transducer/value'];
        break;
      }
    }
  }
  this.inputs = null;
  return this.xf['@@transducer/result'](result);
};
XReduceBy.prototype['@@transducer/step'] = function(result, input) {
  var key = this.keyFn(input);
  this.inputs[key] = this.inputs[key] || [key, this.valueAcc];
  this.inputs[key][1] = this.valueFn(this.inputs[key][1], input);
  return result;
};

var _xreduceBy = _curryN(4, [],
               function _xreduceBy(valueFn, valueAcc, keyFn, xf) {
                 return new XReduceBy(valueFn, valueAcc, keyFn, xf);
               });

/**
 * Groups the elements of the list according to the result of calling
 * the String-returning function `keyFn` on each element and reduces the elements
 * of each group to a single value via the reducer function `valueFn`.
 *
 * This function is basically a more general [`groupBy`](#groupBy) function.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.20.0
 * @category List
 * @sig ((a, b) -> a) -> a -> (b -> String) -> [b] -> {String: a}
 * @param {Function} valueFn The function that reduces the elements of each group to a single
 *        value. Receives two values, accumulator for a particular group and the current element.
 * @param {*} acc The (initial) accumulator value for each group.
 * @param {Function} keyFn The function that maps the list's element into a key.
 * @param {Array} list The array to group.
 * @return {Object} An object with the output of `keyFn` for keys, mapped to the output of
 *         `valueFn` for elements which produced that key when passed to `keyFn`.
 * @see R.groupBy, R.reduce
 * @example
 *
 *      const groupNames = (acc, {name}) => acc.concat(name)
 *      const toGrade = ({score}) =>
 *        score < 65 ? 'F' :
 *        score < 70 ? 'D' :
 *        score < 80 ? 'C' :
 *        score < 90 ? 'B' : 'A'
 *
 *      var students = [
 *        {name: 'Abby', score: 83},
 *        {name: 'Bart', score: 62},
 *        {name: 'Curt', score: 88},
 *        {name: 'Dora', score: 92},
 *      ]
 *
 *      reduceBy(groupNames, [], toGrade, students)
 *      //=> {"A": ["Dora"], "B": ["Abby", "Curt"], "F": ["Bart"]}
 */
var reduceBy = _curryN(4, [], _dispatchable([], _xreduceBy,
  function reduceBy(valueFn, valueAcc, keyFn, list) {
    return _reduce(function(acc, elt) {
      var key = keyFn(elt);
      acc[key] = valueFn(_has(key, acc) ? acc[key] : valueAcc, elt);
      return acc;
    }, {}, list);
  }));

/**
 * Counts the elements of a list according to how many match each value of a
 * key generated by the supplied function. Returns an object mapping the keys
 * produced by `fn` to the number of occurrences in the list. Note that all
 * keys are coerced to strings because of how JavaScript objects work.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig (a -> String) -> [a] -> {*}
 * @param {Function} fn The function used to map values to keys.
 * @param {Array} list The list to count elements from.
 * @return {Object} An object mapping keys to number of occurrences in the list.
 * @example
 *
 *      const numbers = [1.0, 1.1, 1.2, 2.0, 3.0, 2.2];
 *      R.countBy(Math.floor)(numbers);    //=> {'1': 3, '2': 2, '3': 1}
 *
 *      const letters = ['a', 'b', 'A', 'a', 'B', 'c'];
 *      R.countBy(R.toLower)(letters);   //=> {'a': 3, 'b': 2, 'c': 1}
 */
var countBy = reduceBy(function(acc, elem) { return acc + 1; }, 0);

/**
 * Decrements its argument.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Math
 * @sig Number -> Number
 * @param {Number} n
 * @return {Number} n - 1
 * @see R.inc
 * @example
 *
 *      R.dec(42); //=> 41
 */
var dec = add(-1);

/**
 * Returns the second argument if it is not `null`, `undefined` or `NaN`;
 * otherwise the first argument is returned.
 *
 * @func
 * @memberOf R
 * @since v0.10.0
 * @category Logic
 * @sig a -> b -> a | b
 * @param {a} default The default value.
 * @param {b} val `val` will be returned instead of `default` unless `val` is `null`, `undefined` or `NaN`.
 * @return {*} The second value if it is not `null`, `undefined` or `NaN`, otherwise the default value
 * @example
 *
 *      const defaultTo42 = R.defaultTo(42);
 *
 *      defaultTo42(null);  //=> 42
 *      defaultTo42(undefined);  //=> 42
 *      defaultTo42(false);  //=> false
 *      defaultTo42('Ramda');  //=> 'Ramda'
 *      // parseInt('string') results in NaN
 *      defaultTo42(parseInt('string')); //=> 42
 */
var defaultTo = _curry2(function defaultTo(d, v) {
  return v == null || v !== v ? d : v;
});

/**
 * Makes a descending comparator function out of a function that returns a value
 * that can be compared with `<` and `>`.
 *
 * @func
 * @memberOf R
 * @since v0.23.0
 * @category Function
 * @sig Ord b => (a -> b) -> a -> a -> Number
 * @param {Function} fn A function of arity one that returns a value that can be compared
 * @param {*} a The first item to be compared.
 * @param {*} b The second item to be compared.
 * @return {Number} `-1` if fn(a) > fn(b), `1` if fn(b) > fn(a), otherwise `0`
 * @see R.ascend
 * @example
 *
 *      const byAge = R.descend(R.prop('age'));
 *      const people = [
 *        { name: 'Emma', age: 70 },
 *        { name: 'Peter', age: 78 },
 *        { name: 'Mikhail', age: 62 },
 *      ];
 *      const peopleByOldestFirst = R.sort(byAge, people);
 *        //=> [{ name: 'Peter', age: 78 }, { name: 'Emma', age: 70 }, { name: 'Mikhail', age: 62 }]
 */
var descend = _curry3(function descend(fn, a, b) {
  var aa = fn(a);
  var bb = fn(b);
  return aa > bb ? -1 : aa < bb ? 1 : 0;
});

function _Set() {
  /* globals Set */
  this._nativeSet = typeof Set === 'function' ? new Set() : null;
  this._items = {};
}

// until we figure out why jsdoc chokes on this
// @param item The item to add to the Set
// @returns {boolean} true if the item did not exist prior, otherwise false
//
_Set.prototype.add = function(item) {
  return !hasOrAdd(item, true, this);
};

//
// @param item The item to check for existence in the Set
// @returns {boolean} true if the item exists in the Set, otherwise false
//
_Set.prototype.has = function(item) {
  return hasOrAdd(item, false, this);
};

//
// Combines the logic for checking whether an item is a member of the set and
// for adding a new item to the set.
//
// @param item       The item to check or add to the Set instance.
// @param shouldAdd  If true, the item will be added to the set if it doesn't
//                   already exist.
// @param set        The set instance to check or add to.
// @return {boolean} true if the item already existed, otherwise false.
//
function hasOrAdd(item, shouldAdd, set) {
  var type = typeof item;
  var prevSize, newSize;
  switch (type) {
    case 'string':
    case 'number':
      // distinguish between +0 and -0
      if (item === 0 && 1 / item === -Infinity) {
        if (set._items['-0']) {
          return true;
        } else {
          if (shouldAdd) {
            set._items['-0'] = true;
          }
          return false;
        }
      }
      // these types can all utilise the native Set
      if (set._nativeSet !== null) {
        if (shouldAdd) {
          prevSize = set._nativeSet.size;
          set._nativeSet.add(item);
          newSize = set._nativeSet.size;
          return newSize === prevSize;
        } else {
          return set._nativeSet.has(item);
        }
      } else {
        if (!(type in set._items)) {
          if (shouldAdd) {
            set._items[type] = {};
            set._items[type][item] = true;
          }
          return false;
        } else if (item in set._items[type]) {
          return true;
        } else {
          if (shouldAdd) {
            set._items[type][item] = true;
          }
          return false;
        }
      }

    case 'boolean':
      // set._items['boolean'] holds a two element array
      // representing [ falseExists, trueExists ]
      if (type in set._items) {
        var bIdx = item ? 1 : 0;
        if (set._items[type][bIdx]) {
          return true;
        } else {
          if (shouldAdd) {
            set._items[type][bIdx] = true;
          }
          return false;
        }
      } else {
        if (shouldAdd) {
          set._items[type] = item ? [false, true] : [true, false];
        }
        return false;
      }

    case 'function':
      // compare functions for reference equality
      if (set._nativeSet !== null) {
        if (shouldAdd) {
          prevSize = set._nativeSet.size;
          set._nativeSet.add(item);
          newSize = set._nativeSet.size;
          return newSize === prevSize;
        } else {
          return set._nativeSet.has(item);
        }
      } else {
        if (!(type in set._items)) {
          if (shouldAdd) {
            set._items[type] = [item];
          }
          return false;
        }
        if (!_includes(item, set._items[type])) {
          if (shouldAdd) {
            set._items[type].push(item);
          }
          return false;
        }
        return true;
      }

    case 'undefined':
      if (set._items[type]) {
        return true;
      } else {
        if (shouldAdd) {
          set._items[type] = true;
        }
        return false;
      }

    case 'object':
      if (item === null) {
        if (!set._items['null']) {
          if (shouldAdd) {
            set._items['null'] = true;
          }
          return false;
        }
        return true;
      }
    /* falls through */
    default:
      // reduce the search size of heterogeneous sets by creating buckets
      // for each type.
      type = Object.prototype.toString.call(item);
      if (!(type in set._items)) {
        if (shouldAdd) {
          set._items[type] = [item];
        }
        return false;
      }
      // scan through all previously applied items
      if (!_includes(item, set._items[type])) {
        if (shouldAdd) {
          set._items[type].push(item);
        }
        return false;
      }
      return true;
  }
}

/**
 * Finds the set (i.e. no duplicates) of all elements in the first list not
 * contained in the second list. Objects and Arrays are compared in terms of
 * value equality, not reference equality.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig [*] -> [*] -> [*]
 * @param {Array} list1 The first list.
 * @param {Array} list2 The second list.
 * @return {Array} The elements in `list1` that are not in `list2`.
 * @see R.differenceWith, R.symmetricDifference, R.symmetricDifferenceWith, R.without
 * @example
 *
 *      R.difference([1,2,3,4], [7,6,5,4,3]); //=> [1,2]
 *      R.difference([7,6,5,4,3], [1,2,3,4]); //=> [7,6,5]
 *      R.difference([{a: 1}, {b: 2}], [{a: 1}, {c: 3}]) //=> [{b: 2}]
 */
var difference = _curry2(function difference(first, second) {
  var out = [];
  var idx = 0;
  var firstLen = first.length;
  var secondLen = second.length;
  var toFilterOut = new _Set();

  for (var i = 0; i < secondLen; i += 1) {
    toFilterOut.add(second[i]);
  }

  while (idx < firstLen) {
    if (toFilterOut.add(first[idx])) {
      out[out.length] = first[idx];
    }
    idx += 1;
  }
  return out;
});

/**
 * Finds the set (i.e. no duplicates) of all elements in the first list not
 * contained in the second list. Duplication is determined according to the
 * value returned by applying the supplied predicate to two list elements.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig ((a, a) -> Boolean) -> [a] -> [a] -> [a]
 * @param {Function} pred A predicate used to test whether two items are equal.
 * @param {Array} list1 The first list.
 * @param {Array} list2 The second list.
 * @return {Array} The elements in `list1` that are not in `list2`.
 * @see R.difference, R.symmetricDifference, R.symmetricDifferenceWith
 * @example
 *
 *      const cmp = (x, y) => x.a === y.a;
 *      const l1 = [{a: 1}, {a: 2}, {a: 3}];
 *      const l2 = [{a: 3}, {a: 4}];
 *      R.differenceWith(cmp, l1, l2); //=> [{a: 1}, {a: 2}]
 */
var differenceWith = _curry3(function differenceWith(pred, first, second) {
  var out = [];
  var idx = 0;
  var firstLen = first.length;
  while (idx < firstLen) {
    if (!_includesWith(pred, first[idx], second) &&
        !_includesWith(pred, first[idx], out)) {
      out.push(first[idx]);
    }
    idx += 1;
  }
  return out;
});

/**
 * Returns a new object that does not contain a `prop` property.
 *
 * @func
 * @memberOf R
 * @since v0.10.0
 * @category Object
 * @sig String -> {k: v} -> {k: v}
 * @param {String} prop The name of the property to dissociate
 * @param {Object} obj The object to clone
 * @return {Object} A new object equivalent to the original but without the specified property
 * @see R.assoc, R.omit
 * @example
 *
 *      R.dissoc('b', {a: 1, b: 2, c: 3}); //=> {a: 1, c: 3}
 */
var dissoc = _curry2(function dissoc(prop, obj) {
  var result = {};
  for (var p in obj) {
    result[p] = obj[p];
  }
  delete result[prop];
  return result;
});

/**
 * Removes the sub-list of `list` starting at index `start` and containing
 * `count` elements. _Note that this is not destructive_: it returns a copy of
 * the list with the changes.
 * <small>No lists have been harmed in the application of this function.</small>
 *
 * @func
 * @memberOf R
 * @since v0.2.2
 * @category List
 * @sig Number -> Number -> [a] -> [a]
 * @param {Number} start The position to start removing elements
 * @param {Number} count The number of elements to remove
 * @param {Array} list The list to remove from
 * @return {Array} A new Array with `count` elements from `start` removed.
 * @see R.without
 * @example
 *
 *      R.remove(2, 3, [1,2,3,4,5,6,7,8]); //=> [1,2,6,7,8]
 */
var remove = _curry3(function remove(start, count, list) {
  var result = Array.prototype.slice.call(list, 0);
  result.splice(start, count);
  return result;
});

/**
 * Returns a new copy of the array with the element at the provided index
 * replaced with the given value.
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category List
 * @sig Number -> a -> [a] -> [a]
 * @param {Number} idx The index to update.
 * @param {*} x The value to exist at the given index of the returned array.
 * @param {Array|Arguments} list The source array-like object to be updated.
 * @return {Array} A copy of `list` with the value at index `idx` replaced with `x`.
 * @see R.adjust
 * @example
 *
 *      R.update(1, '_', ['a', 'b', 'c']);      //=> ['a', '_', 'c']
 *      R.update(-1, '_', ['a', 'b', 'c']);     //=> ['a', 'b', '_']
 * @symb R.update(-1, a, [b, c]) = [b, a]
 * @symb R.update(0, a, [b, c]) = [a, c]
 * @symb R.update(1, a, [b, c]) = [b, a]
 */
var update = _curry3(function update(idx, x, list) {
  return adjust(idx, always(x), list);
});

/**
 * Makes a shallow clone of an object, omitting the property at the given path.
 * Note that this copies and flattens prototype properties onto the new object
 * as well. All non-primitive properties are copied by reference.
 *
 * @func
 * @memberOf R
 * @since v0.11.0
 * @category Object
 * @typedefn Idx = String | Int
 * @sig [Idx] -> {k: v} -> {k: v}
 * @param {Array} path The path to the value to omit
 * @param {Object} obj The object to clone
 * @return {Object} A new object without the property at path
 * @see R.assocPath
 * @example
 *
 *      R.dissocPath(['a', 'b', 'c'], {a: {b: {c: 42}}}); //=> {a: {b: {}}}
 */
var dissocPath = _curry2(function dissocPath(path, obj) {
  switch (path.length) {
    case 0:
      return obj;
    case 1:
      return _isInteger(path[0]) && _isArray(obj) ? remove(path[0], 1, obj) : dissoc(path[0], obj);
    default:
      var head = path[0];
      var tail = Array.prototype.slice.call(path, 1);
      if (obj[head] == null) {
        return obj;
      } else if (_isInteger(head) && _isArray(obj)) {
        return update(head, dissocPath(tail, obj[head]), obj);
      } else {
        return assoc(head, dissocPath(tail, obj[head]), obj);
      }
  }
});

/**
 * Divides two numbers. Equivalent to `a / b`.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Math
 * @sig Number -> Number -> Number
 * @param {Number} a The first value.
 * @param {Number} b The second value.
 * @return {Number} The result of `a / b`.
 * @see R.multiply
 * @example
 *
 *      R.divide(71, 100); //=> 0.71
 *
 *      const half = R.divide(R.__, 2);
 *      half(42); //=> 21
 *
 *      const reciprocal = R.divide(1);
 *      reciprocal(4);   //=> 0.25
 */
var divide = _curry2(function divide(a, b) { return a / b; });

function XDrop(n, xf) {
  this.xf = xf;
  this.n = n;
}
XDrop.prototype['@@transducer/init'] = _xfBase.init;
XDrop.prototype['@@transducer/result'] = _xfBase.result;
XDrop.prototype['@@transducer/step'] = function(result, input) {
  if (this.n > 0) {
    this.n -= 1;
    return result;
  }
  return this.xf['@@transducer/step'](result, input);
};

var _xdrop = _curry2(function _xdrop(n, xf) { return new XDrop(n, xf); });

/**
 * Returns all but the first `n` elements of the given list, string, or
 * transducer/transformer (or object with a `drop` method).
 *
 * Dispatches to the `drop` method of the second argument, if present.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig Number -> [a] -> [a]
 * @sig Number -> String -> String
 * @param {Number} n
 * @param {*} list
 * @return {*} A copy of list without the first `n` elements
 * @see R.take, R.transduce, R.dropLast, R.dropWhile
 * @example
 *
 *      R.drop(1, ['foo', 'bar', 'baz']); //=> ['bar', 'baz']
 *      R.drop(2, ['foo', 'bar', 'baz']); //=> ['baz']
 *      R.drop(3, ['foo', 'bar', 'baz']); //=> []
 *      R.drop(4, ['foo', 'bar', 'baz']); //=> []
 *      R.drop(3, 'ramda');               //=> 'da'
 */
var drop = _curry2(_dispatchable(['drop'], _xdrop, function drop(n, xs) {
  return slice(Math.max(0, n), Infinity, xs);
}));

function XTake(n, xf) {
  this.xf = xf;
  this.n = n;
  this.i = 0;
}
XTake.prototype['@@transducer/init'] = _xfBase.init;
XTake.prototype['@@transducer/result'] = _xfBase.result;
XTake.prototype['@@transducer/step'] = function(result, input) {
  this.i += 1;
  var ret = this.n === 0 ? result : this.xf['@@transducer/step'](result, input);
  return this.n >= 0 && this.i >= this.n ? _reduced(ret) : ret;
};

var _xtake = _curry2(function _xtake(n, xf) { return new XTake(n, xf); });

/**
 * Returns the first `n` elements of the given list, string, or
 * transducer/transformer (or object with a `take` method).
 *
 * Dispatches to the `take` method of the second argument, if present.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig Number -> [a] -> [a]
 * @sig Number -> String -> String
 * @param {Number} n
 * @param {*} list
 * @return {*}
 * @see R.drop
 * @example
 *
 *      R.take(1, ['foo', 'bar', 'baz']); //=> ['foo']
 *      R.take(2, ['foo', 'bar', 'baz']); //=> ['foo', 'bar']
 *      R.take(3, ['foo', 'bar', 'baz']); //=> ['foo', 'bar', 'baz']
 *      R.take(4, ['foo', 'bar', 'baz']); //=> ['foo', 'bar', 'baz']
 *      R.take(3, 'ramda');               //=> 'ram'
 *
 *      const personnel = [
 *        'Dave Brubeck',
 *        'Paul Desmond',
 *        'Eugene Wright',
 *        'Joe Morello',
 *        'Gerry Mulligan',
 *        'Bob Bates',
 *        'Joe Dodge',
 *        'Ron Crotty'
 *      ];
 *
 *      const takeFive = R.take(5);
 *      takeFive(personnel);
 *      //=> ['Dave Brubeck', 'Paul Desmond', 'Eugene Wright', 'Joe Morello', 'Gerry Mulligan']
 * @symb R.take(-1, [a, b]) = [a, b]
 * @symb R.take(0, [a, b]) = []
 * @symb R.take(1, [a, b]) = [a]
 * @symb R.take(2, [a, b]) = [a, b]
 */
var take = _curry2(_dispatchable(['take'], _xtake, function take(n, xs) {
  return slice(0, n < 0 ? Infinity : n, xs);
}));

function dropLast$2(n, xs) {
  return take(n < xs.length ? xs.length - n : 0, xs);
}

function XDropLast(n, xf) {
  this.xf = xf;
  this.pos = 0;
  this.full = false;
  this.acc = new Array(n);
}
XDropLast.prototype['@@transducer/init'] = _xfBase.init;
XDropLast.prototype['@@transducer/result'] =  function(result) {
  this.acc = null;
  return this.xf['@@transducer/result'](result);
};
XDropLast.prototype['@@transducer/step'] = function(result, input) {
  if (this.full) {
    result = this.xf['@@transducer/step'](result, this.acc[this.pos]);
  }
  this.store(input);
  return result;
};
XDropLast.prototype.store = function(input) {
  this.acc[this.pos] = input;
  this.pos += 1;
  if (this.pos === this.acc.length) {
    this.pos = 0;
    this.full = true;
  }
};

var _xdropLast = _curry2(function _xdropLast(n, xf) { return new XDropLast(n, xf); });

/**
 * Returns a list containing all but the last `n` elements of the given `list`.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category List
 * @sig Number -> [a] -> [a]
 * @sig Number -> String -> String
 * @param {Number} n The number of elements of `list` to skip.
 * @param {Array} list The list of elements to consider.
 * @return {Array} A copy of the list with only the first `list.length - n` elements
 * @see R.takeLast, R.drop, R.dropWhile, R.dropLastWhile
 * @example
 *
 *      R.dropLast(1, ['foo', 'bar', 'baz']); //=> ['foo', 'bar']
 *      R.dropLast(2, ['foo', 'bar', 'baz']); //=> ['foo']
 *      R.dropLast(3, ['foo', 'bar', 'baz']); //=> []
 *      R.dropLast(4, ['foo', 'bar', 'baz']); //=> []
 *      R.dropLast(3, 'ramda');               //=> 'ra'
 */
var dropLast = _curry2(_dispatchable([], _xdropLast, dropLast$2));

function dropLastWhile$2(pred, xs) {
  var idx = xs.length - 1;
  while (idx >= 0 && pred(xs[idx])) {
    idx -= 1;
  }
  return slice(0, idx + 1, xs);
}

function XDropLastWhile(fn, xf) {
  this.f = fn;
  this.retained = [];
  this.xf = xf;
}
XDropLastWhile.prototype['@@transducer/init'] = _xfBase.init;
XDropLastWhile.prototype['@@transducer/result'] = function(result) {
  this.retained = null;
  return this.xf['@@transducer/result'](result);
};
XDropLastWhile.prototype['@@transducer/step'] = function(result, input) {
  return this.f(input) ? this.retain(result, input)
                       : this.flush(result, input);
};
XDropLastWhile.prototype.flush = function(result, input) {
  result = _reduce(
    this.xf['@@transducer/step'],
    result,
    this.retained
  );
  this.retained = [];
  return this.xf['@@transducer/step'](result, input);
};
XDropLastWhile.prototype.retain = function(result, input) {
  this.retained.push(input);
  return result;
};

var _xdropLastWhile = _curry2(function _xdropLastWhile(fn, xf) { return new XDropLastWhile(fn, xf); });

/**
 * Returns a new list excluding all the tailing elements of a given list which
 * satisfy the supplied predicate function. It passes each value from the right
 * to the supplied predicate function, skipping elements until the predicate
 * function returns a `falsy` value. The predicate function is applied to one argument:
 * *(value)*.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category List
 * @sig (a -> Boolean) -> [a] -> [a]
 * @sig (a -> Boolean) -> String -> String
 * @param {Function} predicate The function to be called on each element
 * @param {Array} xs The collection to iterate over.
 * @return {Array} A new array without any trailing elements that return `falsy` values from the `predicate`.
 * @see R.takeLastWhile, R.addIndex, R.drop, R.dropWhile
 * @example
 *
 *      const lteThree = x => x <= 3;
 *
 *      R.dropLastWhile(lteThree, [1, 2, 3, 4, 3, 2, 1]); //=> [1, 2, 3, 4]
 *
 *      R.dropLastWhile(x => x !== 'd' , 'Ramda'); //=> 'Ramd'
 */
var dropLastWhile = _curry2(_dispatchable([], _xdropLastWhile, dropLastWhile$2));

function XDropRepeatsWith(pred, xf) {
  this.xf = xf;
  this.pred = pred;
  this.lastValue = undefined;
  this.seenFirstValue = false;
}

XDropRepeatsWith.prototype['@@transducer/init'] = _xfBase.init;
XDropRepeatsWith.prototype['@@transducer/result'] = _xfBase.result;
XDropRepeatsWith.prototype['@@transducer/step'] = function(result, input) {
  var sameAsLast = false;
  if (!this.seenFirstValue) {
    this.seenFirstValue = true;
  } else if (this.pred(this.lastValue, input)) {
    sameAsLast = true;
  }
  this.lastValue = input;
  return sameAsLast ? result : this.xf['@@transducer/step'](result, input);
};

var _xdropRepeatsWith = _curry2(function _xdropRepeatsWith(pred, xf) { return new XDropRepeatsWith(pred, xf); });

/**
 * Returns the last element of the given list or string.
 *
 * @func
 * @memberOf R
 * @since v0.1.4
 * @category List
 * @sig [a] -> a | Undefined
 * @sig String -> String
 * @param {*} list
 * @return {*}
 * @see R.init, R.head, R.tail
 * @example
 *
 *      R.last(['fi', 'fo', 'fum']); //=> 'fum'
 *      R.last([]); //=> undefined
 *
 *      R.last('abc'); //=> 'c'
 *      R.last(''); //=> ''
 */
var last = nth(-1);

/**
 * Returns a new list without any consecutively repeating elements. Equality is
 * determined by applying the supplied predicate to each pair of consecutive elements. The
 * first element in a series of equal elements will be preserved.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category List
 * @sig ((a, a) -> Boolean) -> [a] -> [a]
 * @param {Function} pred A predicate used to test whether two items are equal.
 * @param {Array} list The array to consider.
 * @return {Array} `list` without repeating elements.
 * @see R.transduce
 * @example
 *
 *      const l = [1, -1, 1, 3, 4, -4, -4, -5, 5, 3, 3];
 *      R.dropRepeatsWith(R.eqBy(Math.abs), l); //=> [1, 3, 4, -5, 3]
 */
var dropRepeatsWith = _curry2(_dispatchable([], _xdropRepeatsWith, function dropRepeatsWith(pred, list) {
  var result = [];
  var idx = 1;
  var len = list.length;
  if (len !== 0) {
    result[0] = list[0];
    while (idx < len) {
      if (!pred(last(result), list[idx])) {
        result[result.length] = list[idx];
      }
      idx += 1;
    }
  }
  return result;
}));

/**
 * Returns a new list without any consecutively repeating elements.
 * [`R.equals`](#equals) is used to determine equality.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category List
 * @sig [a] -> [a]
 * @param {Array} list The array to consider.
 * @return {Array} `list` without repeating elements.
 * @see R.transduce
 * @example
 *
 *     R.dropRepeats([1, 1, 1, 2, 3, 4, 4, 2, 2]); //=> [1, 2, 3, 4, 2]
 */
var dropRepeats = _curry1(_dispatchable([],
                                                      _xdropRepeatsWith(equals),
                                                      dropRepeatsWith(equals)));

function XDropWhile(f, xf) {
  this.xf = xf;
  this.f = f;
}
XDropWhile.prototype['@@transducer/init'] = _xfBase.init;
XDropWhile.prototype['@@transducer/result'] = _xfBase.result;
XDropWhile.prototype['@@transducer/step'] = function(result, input) {
  if (this.f) {
    if (this.f(input)) {
      return result;
    }
    this.f = null;
  }
  return this.xf['@@transducer/step'](result, input);
};

var _xdropWhile = _curry2(function _xdropWhile(f, xf) { return new XDropWhile(f, xf); });

/**
 * Returns a new list excluding the leading elements of a given list which
 * satisfy the supplied predicate function. It passes each value to the supplied
 * predicate function, skipping elements while the predicate function returns
 * `true`. The predicate function is applied to one argument: *(value)*.
 *
 * Dispatches to the `dropWhile` method of the second argument, if present.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category List
 * @sig (a -> Boolean) -> [a] -> [a]
 * @sig (a -> Boolean) -> String -> String
 * @param {Function} fn The function called per iteration.
 * @param {Array} xs The collection to iterate over.
 * @return {Array} A new array.
 * @see R.takeWhile, R.transduce, R.addIndex
 * @example
 *
 *      const lteTwo = x => x <= 2;
 *
 *      R.dropWhile(lteTwo, [1, 2, 3, 4, 3, 2, 1]); //=> [3, 4, 3, 2, 1]
 *
 *      R.dropWhile(x => x !== 'd' , 'Ramda'); //=> 'da'
 */
var dropWhile = _curry2(_dispatchable(['dropWhile'], _xdropWhile, function dropWhile(pred, xs) {
  var idx = 0;
  var len = xs.length;
  while (idx < len && pred(xs[idx])) {
    idx += 1;
  }
  return slice(idx, Infinity, xs);
}));

/**
 * Returns `true` if one or both of its arguments are `true`. Returns `false`
 * if both arguments are `false`.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Logic
 * @sig a -> b -> a | b
 * @param {Any} a
 * @param {Any} b
 * @return {Any} the first argument if truthy, otherwise the second argument.
 * @see R.either
 * @example
 *
 *      R.or(true, true); //=> true
 *      R.or(true, false); //=> true
 *      R.or(false, true); //=> true
 *      R.or(false, false); //=> false
 */
var or = _curry2(function or(a, b) {
  return a || b;
});

/**
 * A function wrapping calls to the two functions in an `||` operation,
 * returning the result of the first function if it is truth-y and the result
 * of the second function otherwise. Note that this is short-circuited,
 * meaning that the second function will not be invoked if the first returns a
 * truth-y value.
 *
 * In addition to functions, `R.either` also accepts any fantasy-land compatible
 * applicative functor.
 *
 * @func
 * @memberOf R
 * @since v0.12.0
 * @category Logic
 * @sig (*... -> Boolean) -> (*... -> Boolean) -> (*... -> Boolean)
 * @param {Function} f a predicate
 * @param {Function} g another predicate
 * @return {Function} a function that applies its arguments to `f` and `g` and `||`s their outputs together.
 * @see R.or
 * @example
 *
 *      const gt10 = x => x > 10;
 *      const even = x => x % 2 === 0;
 *      const f = R.either(gt10, even);
 *      f(101); //=> true
 *      f(8); //=> true
 *
 *      R.either(Maybe.Just(false), Maybe.Just(55)); // => Maybe.Just(55)
 *      R.either([false, false, 'a'], [11]) // => [11, 11, "a"]
 */
var either = _curry2(function either(f, g) {
  return _isFunction(f) ?
    function _either() {
      return f.apply(this, arguments) || g.apply(this, arguments);
    } :
    lift(or)(f, g);
});

/**
 * Returns the empty value of its argument's type. Ramda defines the empty
 * value of Array (`[]`), Object (`{}`), String (`''`), and Arguments. Other
 * types are supported if they define `<Type>.empty`,
 * `<Type>.prototype.empty` or implement the
 * [FantasyLand Monoid spec](https://github.com/fantasyland/fantasy-land#monoid).
 *
 * Dispatches to the `empty` method of the first argument, if present.
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category Function
 * @sig a -> a
 * @param {*} x
 * @return {*}
 * @example
 *
 *      R.empty(Just(42));      //=> Nothing()
 *      R.empty([1, 2, 3]);     //=> []
 *      R.empty('unicorns');    //=> ''
 *      R.empty({x: 1, y: 2});  //=> {}
 */
var empty = _curry1(function empty(x) {
  return (
    (x != null && typeof x['fantasy-land/empty'] === 'function') ?
      x['fantasy-land/empty']() :
    (x != null && x.constructor != null && typeof x.constructor['fantasy-land/empty'] === 'function') ?
      x.constructor['fantasy-land/empty']() :
    (x != null && typeof x.empty === 'function') ?
      x.empty() :
    (x != null && x.constructor != null && typeof x.constructor.empty === 'function') ?
      x.constructor.empty() :
    _isArray(x) ?
      [] :
    _isString(x) ?
      '' :
    _isObject(x) ?
      {} :
    _isArguments(x) ?
      (function() { return arguments; }()) :
    // else
      void 0
  );
});

/**
 * Returns a new list containing the last `n` elements of the given list.
 * If `n > list.length`, returns a list of `list.length` elements.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category List
 * @sig Number -> [a] -> [a]
 * @sig Number -> String -> String
 * @param {Number} n The number of elements to return.
 * @param {Array} xs The collection to consider.
 * @return {Array}
 * @see R.dropLast
 * @example
 *
 *      R.takeLast(1, ['foo', 'bar', 'baz']); //=> ['baz']
 *      R.takeLast(2, ['foo', 'bar', 'baz']); //=> ['bar', 'baz']
 *      R.takeLast(3, ['foo', 'bar', 'baz']); //=> ['foo', 'bar', 'baz']
 *      R.takeLast(4, ['foo', 'bar', 'baz']); //=> ['foo', 'bar', 'baz']
 *      R.takeLast(3, 'ramda');               //=> 'mda'
 */
var takeLast = _curry2(function takeLast(n, xs) {
  return drop(n >= 0 ? xs.length - n : 0, xs);
});

/**
 * Checks if a list ends with the provided sublist.
 *
 * Similarly, checks if a string ends with the provided substring.
 *
 * @func
 * @memberOf R
 * @since v0.24.0
 * @category List
 * @sig [a] -> [a] -> Boolean
 * @sig String -> String -> Boolean
 * @param {*} suffix
 * @param {*} list
 * @return {Boolean}
 * @see R.startsWith
 * @example
 *
 *      R.endsWith('c', 'abc')                //=> true
 *      R.endsWith('b', 'abc')                //=> false
 *      R.endsWith(['c'], ['a', 'b', 'c'])    //=> true
 *      R.endsWith(['b'], ['a', 'b', 'c'])    //=> false
 */
var endsWith = _curry2(function(suffix, list) {
  return equals(takeLast(suffix.length, list), suffix);
});

/**
 * Takes a function and two values in its domain and returns `true` if the
 * values map to the same value in the codomain; `false` otherwise.
 *
 * @func
 * @memberOf R
 * @since v0.18.0
 * @category Relation
 * @sig (a -> b) -> a -> a -> Boolean
 * @param {Function} f
 * @param {*} x
 * @param {*} y
 * @return {Boolean}
 * @example
 *
 *      R.eqBy(Math.abs, 5, -5); //=> true
 */
var eqBy = _curry3(function eqBy(f, x, y) {
  return equals(f(x), f(y));
});

/**
 * Reports whether two objects have the same value, in [`R.equals`](#equals)
 * terms, for the specified property. Useful as a curried predicate.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @sig k -> {k: v} -> {k: v} -> Boolean
 * @param {String} prop The name of the property to compare
 * @param {Object} obj1
 * @param {Object} obj2
 * @return {Boolean}
 *
 * @example
 *
 *      const o1 = { a: 1, b: 2, c: 3, d: 4 };
 *      const o2 = { a: 10, b: 20, c: 3, d: 40 };
 *      R.eqProps('a', o1, o2); //=> false
 *      R.eqProps('c', o1, o2); //=> true
 */
var eqProps = _curry3(function eqProps(prop, obj1, obj2) {
  return equals(obj1[prop], obj2[prop]);
});

/**
 * Creates a new object by recursively evolving a shallow copy of `object`,
 * according to the `transformation` functions. All non-primitive properties
 * are copied by reference.
 *
 * A `transformation` function will not be invoked if its corresponding key
 * does not exist in the evolved object.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Object
 * @sig {k: (v -> v)} -> {k: v} -> {k: v}
 * @param {Object} transformations The object specifying transformation functions to apply
 *        to the object.
 * @param {Object} object The object to be transformed.
 * @return {Object} The transformed object.
 * @example
 *
 *      const tomato = {firstName: '  Tomato ', data: {elapsed: 100, remaining: 1400}, id:123};
 *      const transformations = {
 *        firstName: R.trim,
 *        lastName: R.trim, // Will not get invoked.
 *        data: {elapsed: R.add(1), remaining: R.add(-1)}
 *      };
 *      R.evolve(transformations, tomato); //=> {firstName: 'Tomato', data: {elapsed: 101, remaining: 1399}, id:123}
 */
var evolve = _curry2(function evolve(transformations, object) {
  var result = object instanceof Array ? [] : {};
  var transformation, key, type;
  for (key in object) {
    transformation = transformations[key];
    type = typeof transformation;
    result[key] = type === 'function'                 ? transformation(object[key])
                : transformation && type === 'object' ? evolve(transformation, object[key])
                                                      : object[key];
  }
  return result;
});

function XFind(f, xf) {
  this.xf = xf;
  this.f = f;
  this.found = false;
}
XFind.prototype['@@transducer/init'] = _xfBase.init;
XFind.prototype['@@transducer/result'] = function(result) {
  if (!this.found) {
    result = this.xf['@@transducer/step'](result, void 0);
  }
  return this.xf['@@transducer/result'](result);
};
XFind.prototype['@@transducer/step'] = function(result, input) {
  if (this.f(input)) {
    this.found = true;
    result = _reduced(this.xf['@@transducer/step'](result, input));
  }
  return result;
};

var _xfind = _curry2(function _xfind(f, xf) { return new XFind(f, xf); });

/**
 * Returns the first element of the list which matches the predicate, or
 * `undefined` if no element matches.
 *
 * Dispatches to the `find` method of the second argument, if present.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig (a -> Boolean) -> [a] -> a | undefined
 * @param {Function} fn The predicate function used to determine if the element is the
 *        desired one.
 * @param {Array} list The array to consider.
 * @return {Object} The element found, or `undefined`.
 * @see R.transduce
 * @example
 *
 *      const xs = [{a: 1}, {a: 2}, {a: 3}];
 *      R.find(R.propEq('a', 2))(xs); //=> {a: 2}
 *      R.find(R.propEq('a', 4))(xs); //=> undefined
 */
var find = _curry2(_dispatchable(['find'], _xfind, function find(fn, list) {
  var idx = 0;
  var len = list.length;
  while (idx < len) {
    if (fn(list[idx])) {
      return list[idx];
    }
    idx += 1;
  }
}));

function XFindIndex(f, xf) {
  this.xf = xf;
  this.f = f;
  this.idx = -1;
  this.found = false;
}
XFindIndex.prototype['@@transducer/init'] = _xfBase.init;
XFindIndex.prototype['@@transducer/result'] = function(result) {
  if (!this.found) {
    result = this.xf['@@transducer/step'](result, -1);
  }
  return this.xf['@@transducer/result'](result);
};
XFindIndex.prototype['@@transducer/step'] = function(result, input) {
  this.idx += 1;
  if (this.f(input)) {
    this.found = true;
    result = _reduced(this.xf['@@transducer/step'](result, this.idx));
  }
  return result;
};

var _xfindIndex = _curry2(function _xfindIndex(f, xf) { return new XFindIndex(f, xf); });

/**
 * Returns the index of the first element of the list which matches the
 * predicate, or `-1` if no element matches.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.1.1
 * @category List
 * @sig (a -> Boolean) -> [a] -> Number
 * @param {Function} fn The predicate function used to determine if the element is the
 * desired one.
 * @param {Array} list The array to consider.
 * @return {Number} The index of the element found, or `-1`.
 * @see R.transduce
 * @example
 *
 *      const xs = [{a: 1}, {a: 2}, {a: 3}];
 *      R.findIndex(R.propEq('a', 2))(xs); //=> 1
 *      R.findIndex(R.propEq('a', 4))(xs); //=> -1
 */
var findIndex = _curry2(_dispatchable([], _xfindIndex, function findIndex(fn, list) {
  var idx = 0;
  var len = list.length;
  while (idx < len) {
    if (fn(list[idx])) {
      return idx;
    }
    idx += 1;
  }
  return -1;
}));

function XFindLast(f, xf) {
  this.xf = xf;
  this.f = f;
}
XFindLast.prototype['@@transducer/init'] = _xfBase.init;
XFindLast.prototype['@@transducer/result'] = function(result) {
  return this.xf['@@transducer/result'](this.xf['@@transducer/step'](result, this.last));
};
XFindLast.prototype['@@transducer/step'] = function(result, input) {
  if (this.f(input)) {
    this.last = input;
  }
  return result;
};

var _xfindLast = _curry2(function _xfindLast(f, xf) { return new XFindLast(f, xf); });

/**
 * Returns the last element of the list which matches the predicate, or
 * `undefined` if no element matches.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.1.1
 * @category List
 * @sig (a -> Boolean) -> [a] -> a | undefined
 * @param {Function} fn The predicate function used to determine if the element is the
 * desired one.
 * @param {Array} list The array to consider.
 * @return {Object} The element found, or `undefined`.
 * @see R.transduce
 * @example
 *
 *      const xs = [{a: 1, b: 0}, {a:1, b: 1}];
 *      R.findLast(R.propEq('a', 1))(xs); //=> {a: 1, b: 1}
 *      R.findLast(R.propEq('a', 4))(xs); //=> undefined
 */
var findLast = _curry2(_dispatchable([], _xfindLast, function findLast(fn, list) {
  var idx = list.length - 1;
  while (idx >= 0) {
    if (fn(list[idx])) {
      return list[idx];
    }
    idx -= 1;
  }
}));

function XFindLastIndex(f, xf) {
  this.xf = xf;
  this.f = f;
  this.idx = -1;
  this.lastIdx = -1;
}
XFindLastIndex.prototype['@@transducer/init'] = _xfBase.init;
XFindLastIndex.prototype['@@transducer/result'] = function(result) {
  return this.xf['@@transducer/result'](this.xf['@@transducer/step'](result, this.lastIdx));
};
XFindLastIndex.prototype['@@transducer/step'] = function(result, input) {
  this.idx += 1;
  if (this.f(input)) {
    this.lastIdx = this.idx;
  }
  return result;
};

var _xfindLastIndex = _curry2(function _xfindLastIndex(f, xf) { return new XFindLastIndex(f, xf); });

/**
 * Returns the index of the last element of the list which matches the
 * predicate, or `-1` if no element matches.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.1.1
 * @category List
 * @sig (a -> Boolean) -> [a] -> Number
 * @param {Function} fn The predicate function used to determine if the element is the
 * desired one.
 * @param {Array} list The array to consider.
 * @return {Number} The index of the element found, or `-1`.
 * @see R.transduce
 * @example
 *
 *      const xs = [{a: 1, b: 0}, {a:1, b: 1}];
 *      R.findLastIndex(R.propEq('a', 1))(xs); //=> 1
 *      R.findLastIndex(R.propEq('a', 4))(xs); //=> -1
 */
var findLastIndex = _curry2(_dispatchable([], _xfindLastIndex, function findLastIndex(fn, list) {
  var idx = list.length - 1;
  while (idx >= 0) {
    if (fn(list[idx])) {
      return idx;
    }
    idx -= 1;
  }
  return -1;
}));

/**
 * Returns a new list by pulling every item out of it (and all its sub-arrays)
 * and putting them in a new array, depth-first.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig [a] -> [b]
 * @param {Array} list The array to consider.
 * @return {Array} The flattened list.
 * @see R.unnest
 * @example
 *
 *      R.flatten([1, 2, [3, 4], 5, [6, [7, 8, [9, [10, 11], 12]]]]);
 *      //=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
 */
var flatten = _curry1(_makeFlat(true));

/**
 * Returns a new function much like the supplied one, except that the first two
 * arguments' order is reversed.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig ((a, b, c, ...) -> z) -> (b -> a -> c -> ... -> z)
 * @param {Function} fn The function to invoke with its first two parameters reversed.
 * @return {*} The result of invoking `fn` with its first two parameters' order reversed.
 * @example
 *
 *      const mergeThree = (a, b, c) => [].concat(a, b, c);
 *
 *      mergeThree(1, 2, 3); //=> [1, 2, 3]
 *
 *      R.flip(mergeThree)(1, 2, 3); //=> [2, 1, 3]
 * @symb R.flip(f)(a, b, c) = f(b, a, c)
 */
var flip = _curry1(function flip(fn) {
  return curryN(fn.length, function(a, b) {
    var args = Array.prototype.slice.call(arguments, 0);
    args[0] = b;
    args[1] = a;
    return fn.apply(this, args);
  });
});

/**
 * Iterate over an input `list`, calling a provided function `fn` for each
 * element in the list.
 *
 * `fn` receives one argument: *(value)*.
 *
 * Note: `R.forEach` does not skip deleted or unassigned indices (sparse
 * arrays), unlike the native `Array.prototype.forEach` method. For more
 * details on this behavior, see:
 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach#Description
 *
 * Also note that, unlike `Array.prototype.forEach`, Ramda's `forEach` returns
 * the original array. In some libraries this function is named `each`.
 *
 * Dispatches to the `forEach` method of the second argument, if present.
 *
 * @func
 * @memberOf R
 * @since v0.1.1
 * @category List
 * @sig (a -> *) -> [a] -> [a]
 * @param {Function} fn The function to invoke. Receives one argument, `value`.
 * @param {Array} list The list to iterate over.
 * @return {Array} The original list.
 * @see R.addIndex
 * @example
 *
 *      const printXPlusFive = x => console.log(x + 5);
 *      R.forEach(printXPlusFive, [1, 2, 3]); //=> [1, 2, 3]
 *      // logs 6
 *      // logs 7
 *      // logs 8
 * @symb R.forEach(f, [a, b, c]) = [a, b, c]
 */
var forEach = _curry2(_checkForMethod('forEach', function forEach(fn, list) {
  var len = list.length;
  var idx = 0;
  while (idx < len) {
    fn(list[idx]);
    idx += 1;
  }
  return list;
}));

/**
 * Iterate over an input `object`, calling a provided function `fn` for each
 * key and value in the object.
 *
 * `fn` receives three argument: *(value, key, obj)*.
 *
 * @func
 * @memberOf R
 * @since v0.23.0
 * @category Object
 * @sig ((a, String, StrMap a) -> Any) -> StrMap a -> StrMap a
 * @param {Function} fn The function to invoke. Receives three argument, `value`, `key`, `obj`.
 * @param {Object} obj The object to iterate over.
 * @return {Object} The original object.
 * @example
 *
 *      const printKeyConcatValue = (value, key) => console.log(key + ':' + value);
 *      R.forEachObjIndexed(printKeyConcatValue, {x: 1, y: 2}); //=> {x: 1, y: 2}
 *      // logs x:1
 *      // logs y:2
 * @symb R.forEachObjIndexed(f, {x: a, y: b}) = {x: a, y: b}
 */
var forEachObjIndexed = _curry2(function forEachObjIndexed(fn, obj) {
  var keyList = keys(obj);
  var idx = 0;
  while (idx < keyList.length) {
    var key = keyList[idx];
    fn(obj[key], key, obj);
    idx += 1;
  }
  return obj;
});

/**
 * Creates a new object from a list key-value pairs. If a key appears in
 * multiple pairs, the rightmost pair is included in the object.
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category List
 * @sig [[k,v]] -> {k: v}
 * @param {Array} pairs An array of two-element arrays that will be the keys and values of the output object.
 * @return {Object} The object made by pairing up `keys` and `values`.
 * @see R.toPairs, R.pair
 * @example
 *
 *      R.fromPairs([['a', 1], ['b', 2], ['c', 3]]); //=> {a: 1, b: 2, c: 3}
 */
var fromPairs = _curry1(function fromPairs(pairs) {
  var result = {};
  var idx = 0;
  while (idx < pairs.length) {
    result[pairs[idx][0]] = pairs[idx][1];
    idx += 1;
  }
  return result;
});

/**
 * Splits a list into sub-lists stored in an object, based on the result of
 * calling a String-returning function on each element, and grouping the
 * results according to values returned.
 *
 * Dispatches to the `groupBy` method of the second argument, if present.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig (a -> String) -> [a] -> {String: [a]}
 * @param {Function} fn Function :: a -> String
 * @param {Array} list The array to group
 * @return {Object} An object with the output of `fn` for keys, mapped to arrays of elements
 *         that produced that key when passed to `fn`.
 * @see R.reduceBy, R.transduce
 * @example
 *
 *      const byGrade = R.groupBy(function(student) {
 *        const score = student.score;
 *        return score < 65 ? 'F' :
 *               score < 70 ? 'D' :
 *               score < 80 ? 'C' :
 *               score < 90 ? 'B' : 'A';
 *      });
 *      const students = [{name: 'Abby', score: 84},
 *                      {name: 'Eddy', score: 58},
 *                      // ...
 *                      {name: 'Jack', score: 69}];
 *      byGrade(students);
 *      // {
 *      //   'A': [{name: 'Dianne', score: 99}],
 *      //   'B': [{name: 'Abby', score: 84}]
 *      //   // ...,
 *      //   'F': [{name: 'Eddy', score: 58}]
 *      // }
 */
var groupBy = _curry2(_checkForMethod('groupBy', reduceBy(function(acc, item) {
  if (acc == null) {
    acc = [];
  }
  acc.push(item);
  return acc;
}, null)));

/**
 * Takes a list and returns a list of lists where each sublist's elements are
 * all satisfied pairwise comparison according to the provided function.
 * Only adjacent elements are passed to the comparison function.
 *
 * @func
 * @memberOf R
 * @since v0.21.0
 * @category List
 * @sig ((a, a) → Boolean) → [a] → [[a]]
 * @param {Function} fn Function for determining whether two given (adjacent)
 *        elements should be in the same group
 * @param {Array} list The array to group. Also accepts a string, which will be
 *        treated as a list of characters.
 * @return {List} A list that contains sublists of elements,
 *         whose concatenations are equal to the original list.
 * @example
 *
 * R.groupWith(R.equals, [0, 1, 1, 2, 3, 5, 8, 13, 21])
 * //=> [[0], [1, 1], [2], [3], [5], [8], [13], [21]]
 *
 * R.groupWith((a, b) => a + 1 === b, [0, 1, 1, 2, 3, 5, 8, 13, 21])
 * //=> [[0, 1], [1, 2, 3], [5], [8], [13], [21]]
 *
 * R.groupWith((a, b) => a % 2 === b % 2, [0, 1, 1, 2, 3, 5, 8, 13, 21])
 * //=> [[0], [1, 1], [2], [3, 5], [8], [13, 21]]
 *
 * R.groupWith(R.eqBy(isVowel), 'aestiou')
 * //=> ['ae', 'st', 'iou']
 */
var groupWith = _curry2(function(fn, list) {
  var res = [];
  var idx = 0;
  var len = list.length;
  while (idx < len) {
    var nextidx = idx + 1;
    while (nextidx < len && fn(list[nextidx - 1], list[nextidx])) {
      nextidx += 1;
    }
    res.push(list.slice(idx, nextidx));
    idx = nextidx;
  }
  return res;
});

/**
 * Returns `true` if the first argument is greater than the second; `false`
 * otherwise.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig Ord a => a -> a -> Boolean
 * @param {*} a
 * @param {*} b
 * @return {Boolean}
 * @see R.lt
 * @example
 *
 *      R.gt(2, 1); //=> true
 *      R.gt(2, 2); //=> false
 *      R.gt(2, 3); //=> false
 *      R.gt('a', 'z'); //=> false
 *      R.gt('z', 'a'); //=> true
 */
var gt = _curry2(function gt(a, b) { return a > b; });

/**
 * Returns `true` if the first argument is greater than or equal to the second;
 * `false` otherwise.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig Ord a => a -> a -> Boolean
 * @param {Number} a
 * @param {Number} b
 * @return {Boolean}
 * @see R.lte
 * @example
 *
 *      R.gte(2, 1); //=> true
 *      R.gte(2, 2); //=> true
 *      R.gte(2, 3); //=> false
 *      R.gte('a', 'z'); //=> false
 *      R.gte('z', 'a'); //=> true
 */
var gte = _curry2(function gte(a, b) { return a >= b; });

/**
 * Returns whether or not a path exists in an object. Only the object's
 * own properties are checked.
 *
 * @func
 * @memberOf R
 * @since v0.26.0
 * @category Object
 * @typedefn Idx = String | Int
 * @sig [Idx] -> {a} -> Boolean
 * @param {Array} path The path to use.
 * @param {Object} obj The object to check the path in.
 * @return {Boolean} Whether the path exists.
 * @see R.has
 * @example
 *
 *      R.hasPath(['a', 'b'], {a: {b: 2}});         // => true
 *      R.hasPath(['a', 'b'], {a: {b: undefined}}); // => true
 *      R.hasPath(['a', 'b'], {a: {c: 2}});         // => false
 *      R.hasPath(['a', 'b'], {});                  // => false
 */
var hasPath = _curry2(function hasPath(_path, obj) {
  if (_path.length === 0) {
    return false;
  }
  var val = obj;
  var idx = 0;
  while (idx < _path.length) {
    if (_has(_path[idx], val)) {
      val = val[_path[idx]];
      idx += 1;
    } else {
      return false;
    }
  }
  return true;
});

/**
 * Returns whether or not an object has an own property with the specified name
 *
 * @func
 * @memberOf R
 * @since v0.7.0
 * @category Object
 * @sig s -> {s: x} -> Boolean
 * @param {String} prop The name of the property to check for.
 * @param {Object} obj The object to query.
 * @return {Boolean} Whether the property exists.
 * @example
 *
 *      const hasName = R.has('name');
 *      hasName({name: 'alice'});   //=> true
 *      hasName({name: 'bob'});     //=> true
 *      hasName({});                //=> false
 *
 *      const point = {x: 0, y: 0};
 *      const pointHas = R.has(R.__, point);
 *      pointHas('x');  //=> true
 *      pointHas('y');  //=> true
 *      pointHas('z');  //=> false
 */
var has = _curry2(function has(prop, obj) {
  return hasPath([prop], obj);
});

/**
 * Returns whether or not an object or its prototype chain has a property with
 * the specified name
 *
 * @func
 * @memberOf R
 * @since v0.7.0
 * @category Object
 * @sig s -> {s: x} -> Boolean
 * @param {String} prop The name of the property to check for.
 * @param {Object} obj The object to query.
 * @return {Boolean} Whether the property exists.
 * @example
 *
 *      function Rectangle(width, height) {
 *        this.width = width;
 *        this.height = height;
 *      }
 *      Rectangle.prototype.area = function() {
 *        return this.width * this.height;
 *      };
 *
 *      const square = new Rectangle(2, 2);
 *      R.hasIn('width', square);  //=> true
 *      R.hasIn('area', square);  //=> true
 */
var hasIn = _curry2(function hasIn(prop, obj) {
  return prop in obj;
});

/**
 * Returns true if its arguments are identical, false otherwise. Values are
 * identical if they reference the same memory. `NaN` is identical to `NaN`;
 * `0` and `-0` are not identical.
 *
 * Note this is merely a curried version of ES6 `Object.is`.
 *
 * @func
 * @memberOf R
 * @since v0.15.0
 * @category Relation
 * @sig a -> a -> Boolean
 * @param {*} a
 * @param {*} b
 * @return {Boolean}
 * @example
 *
 *      const o = {};
 *      R.identical(o, o); //=> true
 *      R.identical(1, 1); //=> true
 *      R.identical(1, '1'); //=> false
 *      R.identical([], []); //=> false
 *      R.identical(0, -0); //=> false
 *      R.identical(NaN, NaN); //=> true
 */
var identical = _curry2(_objectIs$1);

/**
 * Creates a function that will process either the `onTrue` or the `onFalse`
 * function depending upon the result of the `condition` predicate.
 *
 * @func
 * @memberOf R
 * @since v0.8.0
 * @category Logic
 * @sig (*... -> Boolean) -> (*... -> *) -> (*... -> *) -> (*... -> *)
 * @param {Function} condition A predicate function
 * @param {Function} onTrue A function to invoke when the `condition` evaluates to a truthy value.
 * @param {Function} onFalse A function to invoke when the `condition` evaluates to a falsy value.
 * @return {Function} A new function that will process either the `onTrue` or the `onFalse`
 *                    function depending upon the result of the `condition` predicate.
 * @see R.unless, R.when, R.cond
 * @example
 *
 *      const incCount = R.ifElse(
 *        R.has('count'),
 *        R.over(R.lensProp('count'), R.inc),
 *        R.assoc('count', 1)
 *      );
 *      incCount({});           //=> { count: 1 }
 *      incCount({ count: 1 }); //=> { count: 2 }
 */
var ifElse = _curry3(function ifElse(condition, onTrue, onFalse) {
  return curryN(Math.max(condition.length, onTrue.length, onFalse.length),
    function _ifElse() {
      return condition.apply(this, arguments) ? onTrue.apply(this, arguments) : onFalse.apply(this, arguments);
    }
  );
});

/**
 * Increments its argument.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Math
 * @sig Number -> Number
 * @param {Number} n
 * @return {Number} n + 1
 * @see R.dec
 * @example
 *
 *      R.inc(42); //=> 43
 */
var inc = add(1);

/**
 * Returns `true` if the specified value is equal, in [`R.equals`](#equals)
 * terms, to at least one element of the given list; `false` otherwise.
 * Works also with strings.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig a -> [a] -> Boolean
 * @param {Object} a The item to compare against.
 * @param {Array} list The array to consider.
 * @return {Boolean} `true` if an equivalent item is in the list, `false` otherwise.
 * @see R.any
 * @example
 *
 *      R.includes(3, [1, 2, 3]); //=> true
 *      R.includes(4, [1, 2, 3]); //=> false
 *      R.includes({ name: 'Fred' }, [{ name: 'Fred' }]); //=> true
 *      R.includes([42], [[42]]); //=> true
 *      R.includes('ba', 'banana'); //=>true
 */
var includes = _curry2(_includes);

/**
 * Given a function that generates a key, turns a list of objects into an
 * object indexing the objects by the given key. Note that if multiple
 * objects generate the same value for the indexing key only the last value
 * will be included in the generated object.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category List
 * @sig (a -> String) -> [{k: v}] -> {k: {k: v}}
 * @param {Function} fn Function :: a -> String
 * @param {Array} array The array of objects to index
 * @return {Object} An object indexing each array element by the given property.
 * @example
 *
 *      const list = [{id: 'xyz', title: 'A'}, {id: 'abc', title: 'B'}];
 *      R.indexBy(R.prop('id'), list);
 *      //=> {abc: {id: 'abc', title: 'B'}, xyz: {id: 'xyz', title: 'A'}}
 */
var indexBy = reduceBy(function(acc, elem) { return elem; }, null);

/**
 * Returns the position of the first occurrence of an item in an array, or -1
 * if the item is not included in the array. [`R.equals`](#equals) is used to
 * determine equality.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig a -> [a] -> Number
 * @param {*} target The item to find.
 * @param {Array} xs The array to search in.
 * @return {Number} the index of the target, or -1 if the target is not found.
 * @see R.lastIndexOf
 * @example
 *
 *      R.indexOf(3, [1,2,3,4]); //=> 2
 *      R.indexOf(10, [1,2,3,4]); //=> -1
 */
var indexOf = _curry2(function indexOf(target, xs) {
  return typeof xs.indexOf === 'function' && !_isArray(xs) ?
    xs.indexOf(target) :
    _indexOf(xs, target, 0);
});

/**
 * Returns all but the last element of the given list or string.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category List
 * @sig [a] -> [a]
 * @sig String -> String
 * @param {*} list
 * @return {*}
 * @see R.last, R.head, R.tail
 * @example
 *
 *      R.init([1, 2, 3]);  //=> [1, 2]
 *      R.init([1, 2]);     //=> [1]
 *      R.init([1]);        //=> []
 *      R.init([]);         //=> []
 *
 *      R.init('abc');  //=> 'ab'
 *      R.init('ab');   //=> 'a'
 *      R.init('a');    //=> ''
 *      R.init('');     //=> ''
 */
var init = slice(0, -1);

/**
 * Takes a predicate `pred`, a list `xs`, and a list `ys`, and returns a list
 * `xs'` comprising each of the elements of `xs` which is equal to one or more
 * elements of `ys` according to `pred`.
 *
 * `pred` must be a binary function expecting an element from each list.
 *
 * `xs`, `ys`, and `xs'` are treated as sets, semantically, so ordering should
 * not be significant, but since `xs'` is ordered the implementation guarantees
 * that its values are in the same order as they appear in `xs`. Duplicates are
 * not removed, so `xs'` may contain duplicates if `xs` contains duplicates.
 *
 * @func
 * @memberOf R
 * @since v0.24.0
 * @category Relation
 * @sig ((a, b) -> Boolean) -> [a] -> [b] -> [a]
 * @param {Function} pred
 * @param {Array} xs
 * @param {Array} ys
 * @return {Array}
 * @see R.intersection
 * @example
 *
 *      R.innerJoin(
 *        (record, id) => record.id === id,
 *        [{id: 824, name: 'Richie Furay'},
 *         {id: 956, name: 'Dewey Martin'},
 *         {id: 313, name: 'Bruce Palmer'},
 *         {id: 456, name: 'Stephen Stills'},
 *         {id: 177, name: 'Neil Young'}],
 *        [177, 456, 999]
 *      );
 *      //=> [{id: 456, name: 'Stephen Stills'}, {id: 177, name: 'Neil Young'}]
 */
var innerJoin = _curry3(function innerJoin(pred, xs, ys) {
  return _filter(function(x) { return _includesWith(pred, x, ys); }, xs);
});

/**
 * Inserts the supplied element into the list, at the specified `index`. _Note that

 * this is not destructive_: it returns a copy of the list with the changes.
 * <small>No lists have been harmed in the application of this function.</small>
 *
 * @func
 * @memberOf R
 * @since v0.2.2
 * @category List
 * @sig Number -> a -> [a] -> [a]
 * @param {Number} index The position to insert the element
 * @param {*} elt The element to insert into the Array
 * @param {Array} list The list to insert into
 * @return {Array} A new Array with `elt` inserted at `index`.
 * @example
 *
 *      R.insert(2, 'x', [1,2,3,4]); //=> [1,2,'x',3,4]
 */
var insert = _curry3(function insert(idx, elt, list) {
  idx = idx < list.length && idx >= 0 ? idx : list.length;
  var result = Array.prototype.slice.call(list, 0);
  result.splice(idx, 0, elt);
  return result;
});

/**
 * Inserts the sub-list into the list, at the specified `index`. _Note that this is not
 * destructive_: it returns a copy of the list with the changes.
 * <small>No lists have been harmed in the application of this function.</small>
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category List
 * @sig Number -> [a] -> [a] -> [a]
 * @param {Number} index The position to insert the sub-list
 * @param {Array} elts The sub-list to insert into the Array
 * @param {Array} list The list to insert the sub-list into
 * @return {Array} A new Array with `elts` inserted starting at `index`.
 * @example
 *
 *      R.insertAll(2, ['x','y','z'], [1,2,3,4]); //=> [1,2,'x','y','z',3,4]
 */
var insertAll = _curry3(function insertAll(idx, elts, list) {
  idx = idx < list.length && idx >= 0 ? idx : list.length;
  return [].concat(Array.prototype.slice.call(list, 0, idx),
                   elts,
                   Array.prototype.slice.call(list, idx));
});

/**
 * Returns a new list containing only one copy of each element in the original
 * list, based upon the value returned by applying the supplied function to
 * each list element. Prefers the first item if the supplied function produces
 * the same value on two items. [`R.equals`](#equals) is used for comparison.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category List
 * @sig (a -> b) -> [a] -> [a]
 * @param {Function} fn A function used to produce a value to use during comparisons.
 * @param {Array} list The array to consider.
 * @return {Array} The list of unique items.
 * @example
 *
 *      R.uniqBy(Math.abs, [-1, -5, 2, 10, 1, 2]); //=> [-1, -5, 2, 10]
 */
var uniqBy = _curry2(function uniqBy(fn, list) {
  var set = new _Set();
  var result = [];
  var idx = 0;
  var appliedItem, item;

  while (idx < list.length) {
    item = list[idx];
    appliedItem = fn(item);
    if (set.add(appliedItem)) {
      result.push(item);
    }
    idx += 1;
  }
  return result;
});

/**
 * Returns a new list containing only one copy of each element in the original
 * list. [`R.equals`](#equals) is used to determine equality.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig [a] -> [a]
 * @param {Array} list The array to consider.
 * @return {Array} The list of unique items.
 * @example
 *
 *      R.uniq([1, 1, 2, 1]); //=> [1, 2]
 *      R.uniq([1, '1']);     //=> [1, '1']
 *      R.uniq([[42], [42]]); //=> [[42]]
 */
var uniq = uniqBy(identity);

/**
 * Combines two lists into a set (i.e. no duplicates) composed of those
 * elements common to both lists.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig [*] -> [*] -> [*]
 * @param {Array} list1 The first list.
 * @param {Array} list2 The second list.
 * @return {Array} The list of elements found in both `list1` and `list2`.
 * @see R.innerJoin
 * @example
 *
 *      R.intersection([1,2,3,4], [7,6,5,4,3]); //=> [4, 3]
 */
var intersection = _curry2(function intersection(list1, list2) {
  var lookupList, filteredList;
  if (list1.length > list2.length) {
    lookupList = list1;
    filteredList = list2;
  } else {
    lookupList = list2;
    filteredList = list1;
  }
  return uniq(_filter(flip(_includes)(lookupList), filteredList));
});

/**
 * Creates a new list with the separator interposed between elements.
 *
 * Dispatches to the `intersperse` method of the second argument, if present.
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category List
 * @sig a -> [a] -> [a]
 * @param {*} separator The element to add to the list.
 * @param {Array} list The list to be interposed.
 * @return {Array} The new list.
 * @example
 *
 *      R.intersperse('a', ['b', 'n', 'n', 's']); //=> ['b', 'a', 'n', 'a', 'n', 'a', 's']
 */
var intersperse = _curry2(_checkForMethod('intersperse', function intersperse(separator, list) {
  var out = [];
  var idx = 0;
  var length = list.length;
  while (idx < length) {
    if (idx === length - 1) {
      out.push(list[idx]);
    } else {
      out.push(list[idx], separator);
    }
    idx += 1;
  }
  return out;
}));

// Based on https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/assign
function _objectAssign(target) {
  if (target == null) {
    throw new TypeError('Cannot convert undefined or null to object');
  }

  var output = Object(target);
  var idx = 1;
  var length = arguments.length;
  while (idx < length) {
    var source = arguments[idx];
    if (source != null) {
      for (var nextKey in source) {
        if (_has(nextKey, source)) {
          output[nextKey] = source[nextKey];
        }
      }
    }
    idx += 1;
  }
  return output;
}

var _objectAssign$1 = typeof Object.assign === 'function' ? Object.assign : _objectAssign;

/**
 * Creates an object containing a single key:value pair.
 *
 * @func
 * @memberOf R
 * @since v0.18.0
 * @category Object
 * @sig String -> a -> {String:a}
 * @param {String} key
 * @param {*} val
 * @return {Object}
 * @see R.pair
 * @example
 *
 *      const matchPhrases = R.compose(
 *        R.objOf('must'),
 *        R.map(R.objOf('match_phrase'))
 *      );
 *      matchPhrases(['foo', 'bar', 'baz']); //=> {must: [{match_phrase: 'foo'}, {match_phrase: 'bar'}, {match_phrase: 'baz'}]}
 */
var objOf = _curry2(function objOf(key, val) {
  var obj = {};
  obj[key] = val;
  return obj;
});

var _stepCatArray = {
  '@@transducer/init': Array,
  '@@transducer/step': function(xs, x) {
    xs.push(x);
    return xs;
  },
  '@@transducer/result': _identity
};
var _stepCatString = {
  '@@transducer/init': String,
  '@@transducer/step': function(a, b) { return a + b; },
  '@@transducer/result': _identity
};
var _stepCatObject = {
  '@@transducer/init': Object,
  '@@transducer/step': function(result, input) {
    return _objectAssign$1(
      result,
      _isArrayLike(input) ? objOf(input[0], input[1]) : input
    );
  },
  '@@transducer/result': _identity
};

function _stepCat(obj) {
  if (_isTransformer(obj)) {
    return obj;
  }
  if (_isArrayLike(obj)) {
    return _stepCatArray;
  }
  if (typeof obj === 'string') {
    return _stepCatString;
  }
  if (typeof obj === 'object') {
    return _stepCatObject;
  }
  throw new Error('Cannot create transformer for ' + obj);
}

/**
 * Transforms the items of the list with the transducer and appends the
 * transformed items to the accumulator using an appropriate iterator function
 * based on the accumulator type.
 *
 * The accumulator can be an array, string, object or a transformer. Iterated
 * items will be appended to arrays and concatenated to strings. Objects will
 * be merged directly or 2-item arrays will be merged as key, value pairs.
 *
 * The accumulator can also be a transformer object that provides a 2-arity
 * reducing iterator function, step, 0-arity initial value function, init, and
 * 1-arity result extraction function result. The step function is used as the
 * iterator function in reduce. The result function is used to convert the
 * final accumulator into the return type and in most cases is R.identity. The
 * init function is used to provide the initial accumulator.
 *
 * The iteration is performed with [`R.reduce`](#reduce) after initializing the
 * transducer.
 *
 * @func
 * @memberOf R
 * @since v0.12.0
 * @category List
 * @sig a -> (b -> b) -> [c] -> a
 * @param {*} acc The initial accumulator value.
 * @param {Function} xf The transducer function. Receives a transformer and returns a transformer.
 * @param {Array} list The list to iterate over.
 * @return {*} The final, accumulated value.
 * @see R.transduce
 * @example
 *
 *      const numbers = [1, 2, 3, 4];
 *      const transducer = R.compose(R.map(R.add(1)), R.take(2));
 *
 *      R.into([], transducer, numbers); //=> [2, 3]
 *
 *      const intoArray = R.into([]);
 *      intoArray(transducer, numbers); //=> [2, 3]
 */
var into = _curry3(function into(acc, xf, list) {
  return _isTransformer(acc) ?
    _reduce(xf(acc), acc['@@transducer/init'](), list) :
    _reduce(xf(_stepCat(acc)), _clone(acc, [], [], false), list);
});

/**
 * Same as [`R.invertObj`](#invertObj), however this accounts for objects with
 * duplicate values by putting the values into an array.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Object
 * @sig {s: x} -> {x: [ s, ... ]}
 * @param {Object} obj The object or array to invert
 * @return {Object} out A new object with keys in an array.
 * @see R.invertObj
 * @example
 *
 *      const raceResultsByFirstName = {
 *        first: 'alice',
 *        second: 'jake',
 *        third: 'alice',
 *      };
 *      R.invert(raceResultsByFirstName);
 *      //=> { 'alice': ['first', 'third'], 'jake':['second'] }
 */
var invert = _curry1(function invert(obj) {
  var props = keys(obj);
  var len = props.length;
  var idx = 0;
  var out = {};

  while (idx < len) {
    var key = props[idx];
    var val = obj[key];
    var list = _has(val, out) ? out[val] : (out[val] = []);
    list[list.length] = key;
    idx += 1;
  }
  return out;
});

/**
 * Returns a new object with the keys of the given object as values, and the
 * values of the given object, which are coerced to strings, as keys. Note
 * that the last key found is preferred when handling the same value.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Object
 * @sig {s: x} -> {x: s}
 * @param {Object} obj The object or array to invert
 * @return {Object} out A new object
 * @see R.invert
 * @example
 *
 *      const raceResults = {
 *        first: 'alice',
 *        second: 'jake'
 *      };
 *      R.invertObj(raceResults);
 *      //=> { 'alice': 'first', 'jake':'second' }
 *
 *      // Alternatively:
 *      const raceResults = ['alice', 'jake'];
 *      R.invertObj(raceResults);
 *      //=> { 'alice': '0', 'jake':'1' }
 */
var invertObj = _curry1(function invertObj(obj) {
  var props = keys(obj);
  var len = props.length;
  var idx = 0;
  var out = {};

  while (idx < len) {
    var key = props[idx];
    out[obj[key]] = key;
    idx += 1;
  }
  return out;
});

/**
 * Turns a named method with a specified arity into a function that can be
 * called directly supplied with arguments and a target object.
 *
 * The returned function is curried and accepts `arity + 1` parameters where
 * the final parameter is the target object.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig Number -> String -> (a -> b -> ... -> n -> Object -> *)
 * @param {Number} arity Number of arguments the returned function should take
 *        before the target object.
 * @param {String} method Name of the method to call.
 * @return {Function} A new curried function.
 * @see R.construct
 * @example
 *
 *      const sliceFrom = R.invoker(1, 'slice');
 *      sliceFrom(6, 'abcdefghijklm'); //=> 'ghijklm'
 *      const sliceFrom6 = R.invoker(2, 'slice')(6);
 *      sliceFrom6(8, 'abcdefghijklm'); //=> 'gh'
 * @symb R.invoker(0, 'method')(o) = o['method']()
 * @symb R.invoker(1, 'method')(a, o) = o['method'](a)
 * @symb R.invoker(2, 'method')(a, b, o) = o['method'](a, b)
 */
var invoker = _curry2(function invoker(arity, method) {
  return curryN(arity + 1, function() {
    var target = arguments[arity];
    if (target != null && _isFunction(target[method])) {
      return target[method].apply(target, Array.prototype.slice.call(arguments, 0, arity));
    }
    throw new TypeError(toString$1(target) + ' does not have a method named "' + method + '"');
  });
});

/**
 * See if an object (`val`) is an instance of the supplied constructor. This
 * function will check up the inheritance chain, if any.
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category Type
 * @sig (* -> {*}) -> a -> Boolean
 * @param {Object} ctor A constructor
 * @param {*} val The value to test
 * @return {Boolean}
 * @example
 *
 *      R.is(Object, {}); //=> true
 *      R.is(Number, 1); //=> true
 *      R.is(Object, 1); //=> false
 *      R.is(String, 's'); //=> true
 *      R.is(String, new String('')); //=> true
 *      R.is(Object, new String('')); //=> true
 *      R.is(Object, 's'); //=> false
 *      R.is(Number, {}); //=> false
 */
var is = _curry2(function is(Ctor, val) {
  return val != null && val.constructor === Ctor || val instanceof Ctor;
});

/**
 * Returns `true` if the given value is its type's empty value; `false`
 * otherwise.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Logic
 * @sig a -> Boolean
 * @param {*} x
 * @return {Boolean}
 * @see R.empty
 * @example
 *
 *      R.isEmpty([1, 2, 3]);   //=> false
 *      R.isEmpty([]);          //=> true
 *      R.isEmpty('');          //=> true
 *      R.isEmpty(null);        //=> false
 *      R.isEmpty({});          //=> true
 *      R.isEmpty({length: 0}); //=> false
 */
var isEmpty = _curry1(function isEmpty(x) {
  return x != null && equals(x, empty(x));
});

/**
 * Returns a string made by inserting the `separator` between each element and
 * concatenating all the elements into a single string.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig String -> [a] -> String
 * @param {Number|String} separator The string used to separate the elements.
 * @param {Array} xs The elements to join into a string.
 * @return {String} str The string made by concatenating `xs` with `separator`.
 * @see R.split
 * @example
 *
 *      const spacer = R.join(' ');
 *      spacer(['a', 2, 3.4]);   //=> 'a 2 3.4'
 *      R.join('|', [1, 2, 3]);    //=> '1|2|3'
 */
var join = invoker(1, 'join');

/**
 * juxt applies a list of functions to a list of values.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category Function
 * @sig [(a, b, ..., m) -> n] -> ((a, b, ..., m) -> [n])
 * @param {Array} fns An array of functions
 * @return {Function} A function that returns a list of values after applying each of the original `fns` to its parameters.
 * @see R.applySpec
 * @example
 *
 *      const getRange = R.juxt([Math.min, Math.max]);
 *      getRange(3, 4, 9, -3); //=> [-3, 9]
 * @symb R.juxt([f, g, h])(a, b) = [f(a, b), g(a, b), h(a, b)]
 */
var juxt = _curry1(function juxt(fns) {
  return converge(function() { return Array.prototype.slice.call(arguments, 0); }, fns);
});

/**
 * Returns a list containing the names of all the properties of the supplied
 * object, including prototype properties.
 * Note that the order of the output array is not guaranteed to be consistent
 * across different JS platforms.
 *
 * @func
 * @memberOf R
 * @since v0.2.0
 * @category Object
 * @sig {k: v} -> [k]
 * @param {Object} obj The object to extract properties from
 * @return {Array} An array of the object's own and prototype properties.
 * @see R.keys, R.valuesIn
 * @example
 *
 *      const F = function() { this.x = 'X'; };
 *      F.prototype.y = 'Y';
 *      const f = new F();
 *      R.keysIn(f); //=> ['x', 'y']
 */
var keysIn = _curry1(function keysIn(obj) {
  var prop;
  var ks = [];
  for (prop in obj) {
    ks[ks.length] = prop;
  }
  return ks;
});

/**
 * Returns the position of the last occurrence of an item in an array, or -1 if
 * the item is not included in the array. [`R.equals`](#equals) is used to
 * determine equality.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig a -> [a] -> Number
 * @param {*} target The item to find.
 * @param {Array} xs The array to search in.
 * @return {Number} the index of the target, or -1 if the target is not found.
 * @see R.indexOf
 * @example
 *
 *      R.lastIndexOf(3, [-1,3,3,0,1,2,3,4]); //=> 6
 *      R.lastIndexOf(10, [1,2,3,4]); //=> -1
 */
var lastIndexOf = _curry2(function lastIndexOf(target, xs) {
  if (typeof xs.lastIndexOf === 'function' && !_isArray(xs)) {
    return xs.lastIndexOf(target);
  } else {
    var idx = xs.length - 1;
    while (idx >= 0) {
      if (equals(xs[idx], target)) {
        return idx;
      }
      idx -= 1;
    }
    return -1;
  }
});

function _isNumber(x) {
  return Object.prototype.toString.call(x) === '[object Number]';
}

/**
 * Returns the number of elements in the array by returning `list.length`.
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category List
 * @sig [a] -> Number
 * @param {Array} list The array to inspect.
 * @return {Number} The length of the array.
 * @example
 *
 *      R.length([]); //=> 0
 *      R.length([1, 2, 3]); //=> 3
 */
var length = _curry1(function length(list) {
  return list != null && _isNumber(list.length) ? list.length : NaN;
});

/**
 * Returns a lens for the given getter and setter functions. The getter "gets"
 * the value of the focus; the setter "sets" the value of the focus. The setter
 * should not mutate the data structure.
 *
 * @func
 * @memberOf R
 * @since v0.8.0
 * @category Object
 * @typedefn Lens s a = Functor f => (a -> f a) -> s -> f s
 * @sig (s -> a) -> ((a, s) -> s) -> Lens s a
 * @param {Function} getter
 * @param {Function} setter
 * @return {Lens}
 * @see R.view, R.set, R.over, R.lensIndex, R.lensProp
 * @example
 *
 *      const xLens = R.lens(R.prop('x'), R.assoc('x'));
 *
 *      R.view(xLens, {x: 1, y: 2});            //=> 1
 *      R.set(xLens, 4, {x: 1, y: 2});          //=> {x: 4, y: 2}
 *      R.over(xLens, R.negate, {x: 1, y: 2});  //=> {x: -1, y: 2}
 */
var lens = _curry2(function lens(getter, setter) {
  return function(toFunctorFn) {
    return function(target) {
      return map(
        function(focus) {
          return setter(focus, target);
        },
        toFunctorFn(getter(target))
      );
    };
  };
});

/**
 * Returns a lens whose focus is the specified index.
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category Object
 * @typedefn Lens s a = Functor f => (a -> f a) -> s -> f s
 * @sig Number -> Lens s a
 * @param {Number} n
 * @return {Lens}
 * @see R.view, R.set, R.over
 * @example
 *
 *      const headLens = R.lensIndex(0);
 *
 *      R.view(headLens, ['a', 'b', 'c']);            //=> 'a'
 *      R.set(headLens, 'x', ['a', 'b', 'c']);        //=> ['x', 'b', 'c']
 *      R.over(headLens, R.toUpper, ['a', 'b', 'c']); //=> ['A', 'b', 'c']
 */
var lensIndex = _curry1(function lensIndex(n) {
  return lens(nth(n), update(n));
});

/**
 * Returns a lens whose focus is the specified path.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category Object
 * @typedefn Idx = String | Int
 * @typedefn Lens s a = Functor f => (a -> f a) -> s -> f s
 * @sig [Idx] -> Lens s a
 * @param {Array} path The path to use.
 * @return {Lens}
 * @see R.view, R.set, R.over
 * @example
 *
 *      const xHeadYLens = R.lensPath(['x', 0, 'y']);
 *
 *      R.view(xHeadYLens, {x: [{y: 2, z: 3}, {y: 4, z: 5}]});
 *      //=> 2
 *      R.set(xHeadYLens, 1, {x: [{y: 2, z: 3}, {y: 4, z: 5}]});
 *      //=> {x: [{y: 1, z: 3}, {y: 4, z: 5}]}
 *      R.over(xHeadYLens, R.negate, {x: [{y: 2, z: 3}, {y: 4, z: 5}]});
 *      //=> {x: [{y: -2, z: 3}, {y: 4, z: 5}]}
 */
var lensPath = _curry1(function lensPath(p) {
  return lens(path(p), assocPath(p));
});

/**
 * Returns a lens whose focus is the specified property.
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category Object
 * @typedefn Lens s a = Functor f => (a -> f a) -> s -> f s
 * @sig String -> Lens s a
 * @param {String} k
 * @return {Lens}
 * @see R.view, R.set, R.over
 * @example
 *
 *      const xLens = R.lensProp('x');
 *
 *      R.view(xLens, {x: 1, y: 2});            //=> 1
 *      R.set(xLens, 4, {x: 1, y: 2});          //=> {x: 4, y: 2}
 *      R.over(xLens, R.negate, {x: 1, y: 2});  //=> {x: -1, y: 2}
 */
var lensProp = _curry1(function lensProp(k) {
  return lens(prop(k), assoc(k));
});

/**
 * Returns `true` if the first argument is less than the second; `false`
 * otherwise.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig Ord a => a -> a -> Boolean
 * @param {*} a
 * @param {*} b
 * @return {Boolean}
 * @see R.gt
 * @example
 *
 *      R.lt(2, 1); //=> false
 *      R.lt(2, 2); //=> false
 *      R.lt(2, 3); //=> true
 *      R.lt('a', 'z'); //=> true
 *      R.lt('z', 'a'); //=> false
 */
var lt = _curry2(function lt(a, b) { return a < b; });

/**
 * Returns `true` if the first argument is less than or equal to the second;
 * `false` otherwise.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig Ord a => a -> a -> Boolean
 * @param {Number} a
 * @param {Number} b
 * @return {Boolean}
 * @see R.gte
 * @example
 *
 *      R.lte(2, 1); //=> false
 *      R.lte(2, 2); //=> true
 *      R.lte(2, 3); //=> true
 *      R.lte('a', 'z'); //=> true
 *      R.lte('z', 'a'); //=> false
 */
var lte = _curry2(function lte(a, b) { return a <= b; });

/**
 * The `mapAccum` function behaves like a combination of map and reduce; it
 * applies a function to each element of a list, passing an accumulating
 * parameter from left to right, and returning a final value of this
 * accumulator together with the new list.
 *
 * The iterator function receives two arguments, *acc* and *value*, and should
 * return a tuple *[acc, value]*.
 *
 * @func
 * @memberOf R
 * @since v0.10.0
 * @category List
 * @sig ((acc, x) -> (acc, y)) -> acc -> [x] -> (acc, [y])
 * @param {Function} fn The function to be called on every element of the input `list`.
 * @param {*} acc The accumulator value.
 * @param {Array} list The list to iterate over.
 * @return {*} The final, accumulated value.
 * @see R.scan, R.addIndex, R.mapAccumRight
 * @example
 *
 *      const digits = ['1', '2', '3', '4'];
 *      const appender = (a, b) => [a + b, a + b];
 *
 *      R.mapAccum(appender, 0, digits); //=> ['01234', ['01', '012', '0123', '01234']]
 * @symb R.mapAccum(f, a, [b, c, d]) = [
 *   f(f(f(a, b)[0], c)[0], d)[0],
 *   [
 *     f(a, b)[1],
 *     f(f(a, b)[0], c)[1],
 *     f(f(f(a, b)[0], c)[0], d)[1]
 *   ]
 * ]
 */
var mapAccum = _curry3(function mapAccum(fn, acc, list) {
  var idx = 0;
  var len = list.length;
  var result = [];
  var tuple = [acc];
  while (idx < len) {
    tuple = fn(tuple[0], list[idx]);
    result[idx] = tuple[1];
    idx += 1;
  }
  return [tuple[0], result];
});

/**
 * The `mapAccumRight` function behaves like a combination of map and reduce; it
 * applies a function to each element of a list, passing an accumulating
 * parameter from right to left, and returning a final value of this
 * accumulator together with the new list.
 *
 * Similar to [`mapAccum`](#mapAccum), except moves through the input list from
 * the right to the left.
 *
 * The iterator function receives two arguments, *acc* and *value*, and should
 * return a tuple *[acc, value]*.
 *
 * @func
 * @memberOf R
 * @since v0.10.0
 * @category List
 * @sig ((acc, x) -> (acc, y)) -> acc -> [x] -> (acc, [y])
 * @param {Function} fn The function to be called on every element of the input `list`.
 * @param {*} acc The accumulator value.
 * @param {Array} list The list to iterate over.
 * @return {*} The final, accumulated value.
 * @see R.addIndex, R.mapAccum
 * @example
 *
 *      const digits = ['1', '2', '3', '4'];
 *      const appender = (a, b) => [b + a, b + a];
 *
 *      R.mapAccumRight(appender, 5, digits); //=> ['12345', ['12345', '2345', '345', '45']]
 * @symb R.mapAccumRight(f, a, [b, c, d]) = [
 *   f(f(f(a, d)[0], c)[0], b)[0],
 *   [
 *     f(a, d)[1],
 *     f(f(a, d)[0], c)[1],
 *     f(f(f(a, d)[0], c)[0], b)[1]
 *   ]
 * ]
 */
var mapAccumRight = _curry3(function mapAccumRight(fn, acc, list) {
  var idx = list.length - 1;
  var result = [];
  var tuple = [acc];
  while (idx >= 0) {
    tuple = fn(tuple[0], list[idx]);
    result[idx] = tuple[1];
    idx -= 1;
  }
  return [tuple[0], result];
});

/**
 * An Object-specific version of [`map`](#map). The function is applied to three
 * arguments: *(value, key, obj)*. If only the value is significant, use
 * [`map`](#map) instead.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Object
 * @sig ((*, String, Object) -> *) -> Object -> Object
 * @param {Function} fn
 * @param {Object} obj
 * @return {Object}
 * @see R.map
 * @example
 *
 *      const xyz = { x: 1, y: 2, z: 3 };
 *      const prependKeyAndDouble = (num, key, obj) => key + (num * 2);
 *
 *      R.mapObjIndexed(prependKeyAndDouble, xyz); //=> { x: 'x2', y: 'y4', z: 'z6' }
 */
var mapObjIndexed = _curry2(function mapObjIndexed(fn, obj) {
  return _reduce(function(acc, key) {
    acc[key] = fn(obj[key], key, obj);
    return acc;
  }, {}, keys(obj));
});

/**
 * Tests a regular expression against a String. Note that this function will
 * return an empty array when there are no matches. This differs from
 * [`String.prototype.match`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/match)
 * which returns `null` when there are no matches.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category String
 * @sig RegExp -> String -> [String | Undefined]
 * @param {RegExp} rx A regular expression.
 * @param {String} str The string to match against
 * @return {Array} The list of matches or empty array.
 * @see R.test
 * @example
 *
 *      R.match(/([a-z]a)/g, 'bananas'); //=> ['ba', 'na', 'na']
 *      R.match(/a/, 'b'); //=> []
 *      R.match(/a/, null); //=> TypeError: null does not have a method named "match"
 */
var match = _curry2(function match(rx, str) {
  return str.match(rx) || [];
});

/**
 * `mathMod` behaves like the modulo operator should mathematically, unlike the
 * `%` operator (and by extension, [`R.modulo`](#modulo)). So while
 * `-17 % 5` is `-2`, `mathMod(-17, 5)` is `3`. `mathMod` requires Integer
 * arguments, and returns NaN when the modulus is zero or negative.
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category Math
 * @sig Number -> Number -> Number
 * @param {Number} m The dividend.
 * @param {Number} p the modulus.
 * @return {Number} The result of `b mod a`.
 * @see R.modulo
 * @example
 *
 *      R.mathMod(-17, 5);  //=> 3
 *      R.mathMod(17, 5);   //=> 2
 *      R.mathMod(17, -5);  //=> NaN
 *      R.mathMod(17, 0);   //=> NaN
 *      R.mathMod(17.2, 5); //=> NaN
 *      R.mathMod(17, 5.3); //=> NaN
 *
 *      const clock = R.mathMod(R.__, 12);
 *      clock(15); //=> 3
 *      clock(24); //=> 0
 *
 *      const seventeenMod = R.mathMod(17);
 *      seventeenMod(3);  //=> 2
 *      seventeenMod(4);  //=> 1
 *      seventeenMod(10); //=> 7
 */
var mathMod = _curry2(function mathMod(m, p) {
  if (!_isInteger(m)) { return NaN; }
  if (!_isInteger(p) || p < 1) { return NaN; }
  return ((m % p) + p) % p;
});

/**
 * Takes a function and two values, and returns whichever value produces the
 * larger result when passed to the provided function.
 *
 * @func
 * @memberOf R
 * @since v0.8.0
 * @category Relation
 * @sig Ord b => (a -> b) -> a -> a -> a
 * @param {Function} f
 * @param {*} a
 * @param {*} b
 * @return {*}
 * @see R.max, R.minBy
 * @example
 *
 *      //  square :: Number -> Number
 *      const square = n => n * n;
 *
 *      R.maxBy(square, -3, 2); //=> -3
 *
 *      R.reduce(R.maxBy(square), 0, [3, -5, 4, 1, -2]); //=> -5
 *      R.reduce(R.maxBy(square), 0, []); //=> 0
 */
var maxBy = _curry3(function maxBy(f, a, b) {
  return f(b) > f(a) ? b : a;
});

/**
 * Adds together all the elements of a list.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Math
 * @sig [Number] -> Number
 * @param {Array} list An array of numbers
 * @return {Number} The sum of all the numbers in the list.
 * @see R.reduce
 * @example
 *
 *      R.sum([2,4,6,8,100,1]); //=> 121
 */
var sum = reduce(add, 0);

/**
 * Returns the mean of the given list of numbers.
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category Math
 * @sig [Number] -> Number
 * @param {Array} list
 * @return {Number}
 * @see R.median
 * @example
 *
 *      R.mean([2, 7, 9]); //=> 6
 *      R.mean([]); //=> NaN
 */
var mean = _curry1(function mean(list) {
  return sum(list) / list.length;
});

/**
 * Returns the median of the given list of numbers.
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category Math
 * @sig [Number] -> Number
 * @param {Array} list
 * @return {Number}
 * @see R.mean
 * @example
 *
 *      R.median([2, 9, 7]); //=> 7
 *      R.median([7, 2, 10, 9]); //=> 8
 *      R.median([]); //=> NaN
 */
var median = _curry1(function median(list) {
  var len = list.length;
  if (len === 0) {
    return NaN;
  }
  var width = 2 - len % 2;
  var idx = (len - width) / 2;
  return mean(Array.prototype.slice.call(list, 0).sort(function(a, b) {
    return a < b ? -1 : a > b ? 1 : 0;
  }).slice(idx, idx + width));
});

/**
 * A customisable version of [`R.memoize`](#memoize). `memoizeWith` takes an
 * additional function that will be applied to a given argument set and used to
 * create the cache key under which the results of the function to be memoized
 * will be stored. Care must be taken when implementing key generation to avoid
 * clashes that may overwrite previous entries erroneously.
 *
 *
 * @func
 * @memberOf R
 * @since v0.24.0
 * @category Function
 * @sig (*... -> String) -> (*... -> a) -> (*... -> a)
 * @param {Function} fn The function to generate the cache key.
 * @param {Function} fn The function to memoize.
 * @return {Function} Memoized version of `fn`.
 * @example
 *
 *      let count = 0;
 *      const factorial = R.memoizeWith(R.identity, n => {
 *        count += 1;
 *        return R.product(R.range(1, n + 1));
 *      });
 *      factorial(5); //=> 120
 *      factorial(5); //=> 120
 *      factorial(5); //=> 120
 *      count; //=> 1
 */
var memoizeWith = _curry2(function memoizeWith(mFn, fn) {
  var cache = {};
  return _arity(fn.length, function() {
    var key = mFn.apply(this, arguments);
    if (!_has(key, cache)) {
      cache[key] = fn.apply(this, arguments);
    }
    return cache[key];
  });
});

/**
 * Create a new object with the own properties of the first object merged with
 * the own properties of the second object. If a key exists in both objects,
 * the value from the second object will be used.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @sig {k: v} -> {k: v} -> {k: v}
 * @param {Object} l
 * @param {Object} r
 * @return {Object}
 * @see R.mergeRight, R.mergeDeepRight, R.mergeWith, R.mergeWithKey
 * @deprecated
 * @example
 *
 *      R.merge({ 'name': 'fred', 'age': 10 }, { 'age': 40 });
 *      //=> { 'name': 'fred', 'age': 40 }
 *
 *      const withDefaults = R.merge({x: 0, y: 0});
 *      withDefaults({y: 2}); //=> {x: 0, y: 2}
 * @symb R.merge(a, b) = {...a, ...b}
 */
var merge = _curry2(function merge(l, r) {
  return _objectAssign$1({}, l, r);
});

/**
 * Merges a list of objects together into one object.
 *
 * @func
 * @memberOf R
 * @since v0.10.0
 * @category List
 * @sig [{k: v}] -> {k: v}
 * @param {Array} list An array of objects
 * @return {Object} A merged object.
 * @see R.reduce
 * @example
 *
 *      R.mergeAll([{foo:1},{bar:2},{baz:3}]); //=> {foo:1,bar:2,baz:3}
 *      R.mergeAll([{foo:1},{foo:2},{bar:2}]); //=> {foo:2,bar:2}
 * @symb R.mergeAll([{ x: 1 }, { y: 2 }, { z: 3 }]) = { x: 1, y: 2, z: 3 }
 */
var mergeAll = _curry1(function mergeAll(list) {
  return _objectAssign$1.apply(null, [{}].concat(list));
});

/**
 * Creates a new object with the own properties of the two provided objects. If
 * a key exists in both objects, the provided function is applied to the key
 * and the values associated with the key in each object, with the result being
 * used as the value associated with the key in the returned object.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category Object
 * @sig ((String, a, a) -> a) -> {a} -> {a} -> {a}
 * @param {Function} fn
 * @param {Object} l
 * @param {Object} r
 * @return {Object}
 * @see R.mergeDeepWithKey, R.merge, R.mergeWith
 * @example
 *
 *      let concatValues = (k, l, r) => k == 'values' ? R.concat(l, r) : r
 *      R.mergeWithKey(concatValues,
 *                     { a: true, thing: 'foo', values: [10, 20] },
 *                     { b: true, thing: 'bar', values: [15, 35] });
 *      //=> { a: true, b: true, thing: 'bar', values: [10, 20, 15, 35] }
 * @symb R.mergeWithKey(f, { x: 1, y: 2 }, { y: 5, z: 3 }) = { x: 1, y: f('y', 2, 5), z: 3 }
 */
var mergeWithKey = _curry3(function mergeWithKey(fn, l, r) {
  var result = {};
  var k;

  for (k in l) {
    if (_has(k, l)) {
      result[k] = _has(k, r) ? fn(k, l[k], r[k]) : l[k];
    }
  }

  for (k in r) {
    if (_has(k, r) && !(_has(k, result))) {
      result[k] = r[k];
    }
  }

  return result;
});

/**
 * Creates a new object with the own properties of the two provided objects.
 * If a key exists in both objects:
 * - and both associated values are also objects then the values will be
 *   recursively merged.
 * - otherwise the provided function is applied to the key and associated values
 *   using the resulting value as the new value associated with the key.
 * If a key only exists in one object, the value will be associated with the key
 * of the resulting object.
 *
 * @func
 * @memberOf R
 * @since v0.24.0
 * @category Object
 * @sig ((String, a, a) -> a) -> {a} -> {a} -> {a}
 * @param {Function} fn
 * @param {Object} lObj
 * @param {Object} rObj
 * @return {Object}
 * @see R.mergeWithKey, R.mergeDeepWith
 * @example
 *
 *      let concatValues = (k, l, r) => k == 'values' ? R.concat(l, r) : r
 *      R.mergeDeepWithKey(concatValues,
 *                         { a: true, c: { thing: 'foo', values: [10, 20] }},
 *                         { b: true, c: { thing: 'bar', values: [15, 35] }});
 *      //=> { a: true, b: true, c: { thing: 'bar', values: [10, 20, 15, 35] }}
 */
var mergeDeepWithKey = _curry3(function mergeDeepWithKey(fn, lObj, rObj) {
  return mergeWithKey(function(k, lVal, rVal) {
    if (_isObject(lVal) && _isObject(rVal)) {
      return mergeDeepWithKey(fn, lVal, rVal);
    } else {
      return fn(k, lVal, rVal);
    }
  }, lObj, rObj);
});

/**
 * Creates a new object with the own properties of the first object merged with
 * the own properties of the second object. If a key exists in both objects:
 * - and both values are objects, the two values will be recursively merged
 * - otherwise the value from the first object will be used.
 *
 * @func
 * @memberOf R
 * @since v0.24.0
 * @category Object
 * @sig {a} -> {a} -> {a}
 * @param {Object} lObj
 * @param {Object} rObj
 * @return {Object}
 * @see R.merge, R.mergeDeepRight, R.mergeDeepWith, R.mergeDeepWithKey
 * @example
 *
 *      R.mergeDeepLeft({ name: 'fred', age: 10, contact: { email: 'moo@example.com' }},
 *                      { age: 40, contact: { email: 'baa@example.com' }});
 *      //=> { name: 'fred', age: 10, contact: { email: 'moo@example.com' }}
 */
var mergeDeepLeft = _curry2(function mergeDeepLeft(lObj, rObj) {
  return mergeDeepWithKey(function(k, lVal, rVal) {
    return lVal;
  }, lObj, rObj);
});

/**
 * Creates a new object with the own properties of the first object merged with
 * the own properties of the second object. If a key exists in both objects:
 * - and both values are objects, the two values will be recursively merged
 * - otherwise the value from the second object will be used.
 *
 * @func
 * @memberOf R
 * @since v0.24.0
 * @category Object
 * @sig {a} -> {a} -> {a}
 * @param {Object} lObj
 * @param {Object} rObj
 * @return {Object}
 * @see R.merge, R.mergeDeepLeft, R.mergeDeepWith, R.mergeDeepWithKey
 * @example
 *
 *      R.mergeDeepRight({ name: 'fred', age: 10, contact: { email: 'moo@example.com' }},
 *                       { age: 40, contact: { email: 'baa@example.com' }});
 *      //=> { name: 'fred', age: 40, contact: { email: 'baa@example.com' }}
 */
var mergeDeepRight = _curry2(function mergeDeepRight(lObj, rObj) {
  return mergeDeepWithKey(function(k, lVal, rVal) {
    return rVal;
  }, lObj, rObj);
});

/**
 * Creates a new object with the own properties of the two provided objects.
 * If a key exists in both objects:
 * - and both associated values are also objects then the values will be
 *   recursively merged.
 * - otherwise the provided function is applied to associated values using the
 *   resulting value as the new value associated with the key.
 * If a key only exists in one object, the value will be associated with the key
 * of the resulting object.
 *
 * @func
 * @memberOf R
 * @since v0.24.0
 * @category Object
 * @sig ((a, a) -> a) -> {a} -> {a} -> {a}
 * @param {Function} fn
 * @param {Object} lObj
 * @param {Object} rObj
 * @return {Object}
 * @see R.mergeWith, R.mergeDeepWithKey
 * @example
 *
 *      R.mergeDeepWith(R.concat,
 *                      { a: true, c: { values: [10, 20] }},
 *                      { b: true, c: { values: [15, 35] }});
 *      //=> { a: true, b: true, c: { values: [10, 20, 15, 35] }}
 */
var mergeDeepWith = _curry3(function mergeDeepWith(fn, lObj, rObj) {
  return mergeDeepWithKey(function(k, lVal, rVal) {
    return fn(lVal, rVal);
  }, lObj, rObj);
});

/**
 * Create a new object with the own properties of the first object merged with
 * the own properties of the second object. If a key exists in both objects,
 * the value from the first object will be used.
 *
 * @func
 * @memberOf R
 * @category Object
 * @sig {k: v} -> {k: v} -> {k: v}
 * @param {Object} l
 * @param {Object} r
 * @return {Object}
 * @see R.mergeRight, R.mergeDeepLeft, R.mergeWith, R.mergeWithKey
 * @example
 *
 *      R.mergeLeft({ 'age': 40 }, { 'name': 'fred', 'age': 10 });
 *      //=> { 'name': 'fred', 'age': 40 }
 *
 *      const resetToDefault = R.mergeLeft({x: 0});
 *      resetToDefault({x: 5, y: 2}); //=> {x: 0, y: 2}
 * @symb R.mergeLeft(a, b) = {...b, ...a}
 */
var mergeLeft = _curry2(function mergeLeft(l, r) {
  return _objectAssign$1({}, r, l);
});

/**
 * Create a new object with the own properties of the first object merged with
 * the own properties of the second object. If a key exists in both objects,
 * the value from the second object will be used.
 *
 * @func
 * @memberOf R
 * @category Object
 * @sig {k: v} -> {k: v} -> {k: v}
 * @param {Object} l
 * @param {Object} r
 * @return {Object}
 * @see R.mergeLeft, R.mergeDeepRight, R.mergeWith, R.mergeWithKey
 * @example
 *
 *      R.mergeRight({ 'name': 'fred', 'age': 10 }, { 'age': 40 });
 *      //=> { 'name': 'fred', 'age': 40 }
 *
 *      const withDefaults = R.mergeRight({x: 0, y: 0});
 *      withDefaults({y: 2}); //=> {x: 0, y: 2}
 * @symb R.mergeRight(a, b) = {...a, ...b}
 */
var mergeRight = _curry2(function mergeRight(l, r) {
  return _objectAssign$1({}, l, r);
});

/**
 * Creates a new object with the own properties of the two provided objects. If
 * a key exists in both objects, the provided function is applied to the values
 * associated with the key in each object, with the result being used as the
 * value associated with the key in the returned object.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category Object
 * @sig ((a, a) -> a) -> {a} -> {a} -> {a}
 * @param {Function} fn
 * @param {Object} l
 * @param {Object} r
 * @return {Object}
 * @see R.mergeDeepWith, R.merge, R.mergeWithKey
 * @example
 *
 *      R.mergeWith(R.concat,
 *                  { a: true, values: [10, 20] },
 *                  { b: true, values: [15, 35] });
 *      //=> { a: true, b: true, values: [10, 20, 15, 35] }
 */
var mergeWith = _curry3(function mergeWith(fn, l, r) {
  return mergeWithKey(function(_, _l, _r) {
    return fn(_l, _r);
  }, l, r);
});

/**
 * Returns the smaller of its two arguments.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig Ord a => a -> a -> a
 * @param {*} a
 * @param {*} b
 * @return {*}
 * @see R.minBy, R.max
 * @example
 *
 *      R.min(789, 123); //=> 123
 *      R.min('a', 'b'); //=> 'a'
 */
var min = _curry2(function min(a, b) { return b < a ? b : a; });

/**
 * Takes a function and two values, and returns whichever value produces the
 * smaller result when passed to the provided function.
 *
 * @func
 * @memberOf R
 * @since v0.8.0
 * @category Relation
 * @sig Ord b => (a -> b) -> a -> a -> a
 * @param {Function} f
 * @param {*} a
 * @param {*} b
 * @return {*}
 * @see R.min, R.maxBy
 * @example
 *
 *      //  square :: Number -> Number
 *      const square = n => n * n;
 *
 *      R.minBy(square, -3, 2); //=> 2
 *
 *      R.reduce(R.minBy(square), Infinity, [3, -5, 4, 1, -2]); //=> 1
 *      R.reduce(R.minBy(square), Infinity, []); //=> Infinity
 */
var minBy = _curry3(function minBy(f, a, b) {
  return f(b) < f(a) ? b : a;
});

/**
 * Divides the first parameter by the second and returns the remainder. Note
 * that this function preserves the JavaScript-style behavior for modulo. For
 * mathematical modulo see [`mathMod`](#mathMod).
 *
 * @func
 * @memberOf R
 * @since v0.1.1
 * @category Math
 * @sig Number -> Number -> Number
 * @param {Number} a The value to the divide.
 * @param {Number} b The pseudo-modulus
 * @return {Number} The result of `b % a`.
 * @see R.mathMod
 * @example
 *
 *      R.modulo(17, 3); //=> 2
 *      // JS behavior:
 *      R.modulo(-17, 3); //=> -2
 *      R.modulo(17, -3); //=> 2
 *
 *      const isOdd = R.modulo(R.__, 2);
 *      isOdd(42); //=> 0
 *      isOdd(21); //=> 1
 */
var modulo = _curry2(function modulo(a, b) { return a % b; });

/**
 * Multiplies two numbers. Equivalent to `a * b` but curried.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Math
 * @sig Number -> Number -> Number
 * @param {Number} a The first value.
 * @param {Number} b The second value.
 * @return {Number} The result of `a * b`.
 * @see R.divide
 * @example
 *
 *      const double = R.multiply(2);
 *      const triple = R.multiply(3);
 *      double(3);       //=>  6
 *      triple(4);       //=> 12
 *      R.multiply(2, 5);  //=> 10
 */
var multiply = _curry2(function multiply(a, b) { return a * b; });

/**
 * Negates its argument.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Math
 * @sig Number -> Number
 * @param {Number} n
 * @return {Number}
 * @example
 *
 *      R.negate(42); //=> -42
 */
var negate = _curry1(function negate(n) { return -n; });

/**
 * Returns `true` if no elements of the list match the predicate, `false`
 * otherwise.
 *
 * Dispatches to the `all` method of the second argument, if present.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.12.0
 * @category List
 * @sig (a -> Boolean) -> [a] -> Boolean
 * @param {Function} fn The predicate function.
 * @param {Array} list The array to consider.
 * @return {Boolean} `true` if the predicate is not satisfied by every element, `false` otherwise.
 * @see R.all, R.any
 * @example
 *
 *      const isEven = n => n % 2 === 0;
 *      const isOdd = n => n % 2 === 1;
 *
 *      R.none(isEven, [1, 3, 5, 7, 9, 11]); //=> true
 *      R.none(isOdd, [1, 3, 5, 7, 8, 11]); //=> false
 */
const none = _curry2(function none(fn, input) {
  return all(_complement(fn), input);
});

/**
 * Returns a function which returns its nth argument.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category Function
 * @sig Number -> *... -> *
 * @param {Number} n
 * @return {Function}
 * @example
 *
 *      R.nthArg(1)('a', 'b', 'c'); //=> 'b'
 *      R.nthArg(-1)('a', 'b', 'c'); //=> 'c'
 * @symb R.nthArg(-1)(a, b, c) = c
 * @symb R.nthArg(0)(a, b, c) = a
 * @symb R.nthArg(1)(a, b, c) = b
 */
var nthArg = _curry1(function nthArg(n) {
  var arity = n < 0 ? 1 : n + 1;
  return curryN(arity, function() {
    return nth(n, arguments);
  });
});

/**
 * `o` is a curried composition function that returns a unary function.
 * Like [`compose`](#compose), `o` performs right-to-left function composition.
 * Unlike [`compose`](#compose), the rightmost function passed to `o` will be
 * invoked with only one argument. Also, unlike [`compose`](#compose), `o` is
 * limited to accepting only 2 unary functions. The name o was chosen because
 * of its similarity to the mathematical composition operator ∘.
 *
 * @func
 * @memberOf R
 * @since v0.24.0
 * @category Function
 * @sig (b -> c) -> (a -> b) -> a -> c
 * @param {Function} f
 * @param {Function} g
 * @return {Function}
 * @see R.compose, R.pipe
 * @example
 *
 *      const classyGreeting = name => "The name's " + name.last + ", " + name.first + " " + name.last
 *      const yellGreeting = R.o(R.toUpper, classyGreeting);
 *      yellGreeting({first: 'James', last: 'Bond'}); //=> "THE NAME'S BOND, JAMES BOND"
 *
 *      R.o(R.multiply(10), R.add(10))(-4) //=> 60
 *
 * @symb R.o(f, g, x) = f(g(x))
 */
var o = _curry3(function o(f, g, x) {
  return f(g(x));
});

function _of(x) { return [x]; }

/**
 * Returns a singleton array containing the value provided.
 *
 * Note this `of` is different from the ES6 `of`; See
 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/of
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category Function
 * @sig a -> [a]
 * @param {*} x any value
 * @return {Array} An array wrapping `x`.
 * @example
 *
 *      R.of(null); //=> [null]
 *      R.of([42]); //=> [[42]]
 */
var of = _curry1(_of);

/**
 * Returns a partial copy of an object omitting the keys specified.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @sig [String] -> {String: *} -> {String: *}
 * @param {Array} names an array of String property names to omit from the new object
 * @param {Object} obj The object to copy from
 * @return {Object} A new object with properties from `names` not on it.
 * @see R.pick
 * @example
 *
 *      R.omit(['a', 'd'], {a: 1, b: 2, c: 3, d: 4}); //=> {b: 2, c: 3}
 */
var omit = _curry2(function omit(names, obj) {
  var result = {};
  var index = {};
  var idx = 0;
  var len = names.length;

  while (idx < len) {
    index[names[idx]] = 1;
    idx += 1;
  }

  for (var prop in obj) {
    if (!index.hasOwnProperty(prop)) {
      result[prop] = obj[prop];
    }
  }
  return result;
});

/**
 * Accepts a function `fn` and returns a function that guards invocation of
 * `fn` such that `fn` can only ever be called once, no matter how many times
 * the returned function is invoked. The first value calculated is returned in
 * subsequent invocations.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig (a... -> b) -> (a... -> b)
 * @param {Function} fn The function to wrap in a call-only-once wrapper.
 * @return {Function} The wrapped function.
 * @example
 *
 *      const addOneOnce = R.once(x => x + 1);
 *      addOneOnce(10); //=> 11
 *      addOneOnce(addOneOnce(50)); //=> 11
 */
var once = _curry1(function once(fn) {
  var called = false;
  var result;
  return _arity(fn.length, function() {
    if (called) {
      return result;
    }
    called = true;
    result = fn.apply(this, arguments);
    return result;
  });
});

function _assertPromise(name, p) {
  if (p == null || !_isFunction(p.then)) {
    throw new TypeError('`' + name + '` expected a Promise, received ' + _toString(p, []));
  }
}

/**
 * Returns the result of applying the onFailure function to the value inside
 * a failed promise. This is useful for handling rejected promises
 * inside function compositions.
 *
 * @func
 * @memberOf R
 * @category Function
 * @sig (e -> b) -> (Promise e a) -> (Promise e b)
 * @sig (e -> (Promise f b)) -> (Promise e a) -> (Promise f b)
 * @param {Function} onFailure The function to apply. Can return a value or a promise of a value.
 * @param {Promise} p
 * @return {Promise} The result of calling `p.then(null, onFailure)`
 * @see R.then
 * @example
 *
 *      var failedFetch = (id) => Promise.reject('bad ID');
 *      var useDefault = () => ({ firstName: 'Bob', lastName: 'Loblaw' })
 *
 *      //recoverFromFailure :: String -> Promise ({firstName, lastName})
 *      var recoverFromFailure = R.pipe(
 *        failedFetch(12345),
 *        R.otherwise(useDefault),
 *        R.then(R.pick(['firstName', 'lastName']))
 *      );
 */
const otherwise = _curry2(function otherwise(f, p) {
  _assertPromise('otherwise', p);

  return p.then(null, f);
});

// `Identity` is a functor that holds a single value, where `map` simply
// transforms the held value with the provided function.
var Identity = function(x) {
  return {value: x, map: function(f) { return Identity(f(x)); }};
};


/**
 * Returns the result of "setting" the portion of the given data structure
 * focused by the given lens to the result of applying the given function to
 * the focused value.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category Object
 * @typedefn Lens s a = Functor f => (a -> f a) -> s -> f s
 * @sig Lens s a -> (a -> a) -> s -> s
 * @param {Lens} lens
 * @param {*} v
 * @param {*} x
 * @return {*}
 * @see R.prop, R.lensIndex, R.lensProp
 * @example
 *
 *      const headLens = R.lensIndex(0);
 *
 *      R.over(headLens, R.toUpper, ['foo', 'bar', 'baz']); //=> ['FOO', 'bar', 'baz']
 */
var over = _curry3(function over(lens, f, x) {
  // The value returned by the getter function is first transformed with `f`,
  // then set as the value of an `Identity`. This is then mapped over with the
  // setter function of the lens.
  return lens(function(y) { return Identity(f(y)); })(x).value;
});

/**
 * Takes two arguments, `fst` and `snd`, and returns `[fst, snd]`.
 *
 * @func
 * @memberOf R
 * @since v0.18.0
 * @category List
 * @sig a -> b -> (a,b)
 * @param {*} fst
 * @param {*} snd
 * @return {Array}
 * @see R.objOf, R.of
 * @example
 *
 *      R.pair('foo', 'bar'); //=> ['foo', 'bar']
 */
var pair = _curry2(function pair(fst, snd) { return [fst, snd]; });

function _createPartialApplicator(concat) {
  return _curry2(function(fn, args) {
    return _arity(Math.max(0, fn.length - args.length), function() {
      return fn.apply(this, concat(args, arguments));
    });
  });
}

/**
 * Takes a function `f` and a list of arguments, and returns a function `g`.
 * When applied, `g` returns the result of applying `f` to the arguments
 * provided initially followed by the arguments provided to `g`.
 *
 * @func
 * @memberOf R
 * @since v0.10.0
 * @category Function
 * @sig ((a, b, c, ..., n) -> x) -> [a, b, c, ...] -> ((d, e, f, ..., n) -> x)
 * @param {Function} f
 * @param {Array} args
 * @return {Function}
 * @see R.partialRight, R.curry
 * @example
 *
 *      const multiply2 = (a, b) => a * b;
 *      const double = R.partial(multiply2, [2]);
 *      double(2); //=> 4
 *
 *      const greet = (salutation, title, firstName, lastName) =>
 *        salutation + ', ' + title + ' ' + firstName + ' ' + lastName + '!';
 *
 *      const sayHello = R.partial(greet, ['Hello']);
 *      const sayHelloToMs = R.partial(sayHello, ['Ms.']);
 *      sayHelloToMs('Jane', 'Jones'); //=> 'Hello, Ms. Jane Jones!'
 * @symb R.partial(f, [a, b])(c, d) = f(a, b, c, d)
 */
var partial = _createPartialApplicator(_concat);

/**
 * Takes a function `f` and a list of arguments, and returns a function `g`.
 * When applied, `g` returns the result of applying `f` to the arguments
 * provided to `g` followed by the arguments provided initially.
 *
 * @func
 * @memberOf R
 * @since v0.10.0
 * @category Function
 * @sig ((a, b, c, ..., n) -> x) -> [d, e, f, ..., n] -> ((a, b, c, ...) -> x)
 * @param {Function} f
 * @param {Array} args
 * @return {Function}
 * @see R.partial
 * @example
 *
 *      const greet = (salutation, title, firstName, lastName) =>
 *        salutation + ', ' + title + ' ' + firstName + ' ' + lastName + '!';
 *
 *      const greetMsJaneJones = R.partialRight(greet, ['Ms.', 'Jane', 'Jones']);
 *
 *      greetMsJaneJones('Hello'); //=> 'Hello, Ms. Jane Jones!'
 * @symb R.partialRight(f, [a, b])(c, d) = f(c, d, a, b)
 */
var partialRight = _createPartialApplicator(flip(_concat));

/**
 * Takes a predicate and a list or other `Filterable` object and returns the
 * pair of filterable objects of the same type of elements which do and do not
 * satisfy, the predicate, respectively. Filterable objects include plain objects or any object
 * that has a filter method such as `Array`.
 *
 * @func
 * @memberOf R
 * @since v0.1.4
 * @category List
 * @sig Filterable f => (a -> Boolean) -> f a -> [f a, f a]
 * @param {Function} pred A predicate to determine which side the element belongs to.
 * @param {Array} filterable the list (or other filterable) to partition.
 * @return {Array} An array, containing first the subset of elements that satisfy the
 *         predicate, and second the subset of elements that do not satisfy.
 * @see R.filter, R.reject
 * @example
 *
 *      R.partition(R.includes('s'), ['sss', 'ttt', 'foo', 'bars']);
 *      // => [ [ 'sss', 'bars' ],  [ 'ttt', 'foo' ] ]
 *
 *      R.partition(R.includes('s'), { a: 'sss', b: 'ttt', foo: 'bars' });
 *      // => [ { a: 'sss', foo: 'bars' }, { b: 'ttt' }  ]
 */
var partition = juxt([filter, reject]);

/**
 * Determines whether a nested path on an object has a specific value, in
 * [`R.equals`](#equals) terms. Most likely used to filter a list.
 *
 * @func
 * @memberOf R
 * @since v0.7.0
 * @category Relation
 * @typedefn Idx = String | Int
 * @sig [Idx] -> a -> {a} -> Boolean
 * @param {Array} path The path of the nested property to use
 * @param {*} val The value to compare the nested property with
 * @param {Object} obj The object to check the nested property in
 * @return {Boolean} `true` if the value equals the nested object property,
 *         `false` otherwise.
 * @example
 *
 *      const user1 = { address: { zipCode: 90210 } };
 *      const user2 = { address: { zipCode: 55555 } };
 *      const user3 = { name: 'Bob' };
 *      const users = [ user1, user2, user3 ];
 *      const isFamous = R.pathEq(['address', 'zipCode'], 90210);
 *      R.filter(isFamous, users); //=> [ user1 ]
 */
var pathEq = _curry3(function pathEq(_path, val, obj) {
  return equals(path(_path, obj), val);
});

/**
 * If the given, non-null object has a value at the given path, returns the
 * value at that path. Otherwise returns the provided default value.
 *
 * @func
 * @memberOf R
 * @since v0.18.0
 * @category Object
 * @typedefn Idx = String | Int
 * @sig a -> [Idx] -> {a} -> a
 * @param {*} d The default value.
 * @param {Array} p The path to use.
 * @param {Object} obj The object to retrieve the nested property from.
 * @return {*} The data at `path` of the supplied object or the default value.
 * @example
 *
 *      R.pathOr('N/A', ['a', 'b'], {a: {b: 2}}); //=> 2
 *      R.pathOr('N/A', ['a', 'b'], {c: {b: 2}}); //=> "N/A"
 */
var pathOr = _curry3(function pathOr(d, p, obj) {
  return defaultTo(d, path(p, obj));
});

/**
 * Returns `true` if the specified object property at given path satisfies the
 * given predicate; `false` otherwise.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category Logic
 * @typedefn Idx = String | Int
 * @sig (a -> Boolean) -> [Idx] -> {a} -> Boolean
 * @param {Function} pred
 * @param {Array} propPath
 * @param {*} obj
 * @return {Boolean}
 * @see R.propSatisfies, R.path
 * @example
 *
 *      R.pathSatisfies(y => y > 0, ['x', 'y'], {x: {y: 2}}); //=> true
 */
var pathSatisfies = _curry3(function pathSatisfies(pred, propPath, obj) {
  return propPath.length > 0 && pred(path(propPath, obj));
});

/**
 * Returns a partial copy of an object containing only the keys specified. If
 * the key does not exist, the property is ignored.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @sig [k] -> {k: v} -> {k: v}
 * @param {Array} names an array of String property names to copy onto a new object
 * @param {Object} obj The object to copy from
 * @return {Object} A new object with only properties from `names` on it.
 * @see R.omit, R.props
 * @example
 *
 *      R.pick(['a', 'd'], {a: 1, b: 2, c: 3, d: 4}); //=> {a: 1, d: 4}
 *      R.pick(['a', 'e', 'f'], {a: 1, b: 2, c: 3, d: 4}); //=> {a: 1}
 */
var pick = _curry2(function pick(names, obj) {
  var result = {};
  var idx = 0;
  while (idx < names.length) {
    if (names[idx] in obj) {
      result[names[idx]] = obj[names[idx]];
    }
    idx += 1;
  }
  return result;
});

/**
 * Similar to `pick` except that this one includes a `key: undefined` pair for
 * properties that don't exist.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @sig [k] -> {k: v} -> {k: v}
 * @param {Array} names an array of String property names to copy onto a new object
 * @param {Object} obj The object to copy from
 * @return {Object} A new object with only properties from `names` on it.
 * @see R.pick
 * @example
 *
 *      R.pickAll(['a', 'd'], {a: 1, b: 2, c: 3, d: 4}); //=> {a: 1, d: 4}
 *      R.pickAll(['a', 'e', 'f'], {a: 1, b: 2, c: 3, d: 4}); //=> {a: 1, e: undefined, f: undefined}
 */
var pickAll = _curry2(function pickAll(names, obj) {
  var result = {};
  var idx = 0;
  var len = names.length;
  while (idx < len) {
    var name = names[idx];
    result[name] = obj[name];
    idx += 1;
  }
  return result;
});

/**
 * Returns a partial copy of an object containing only the keys that satisfy
 * the supplied predicate.
 *
 * @func
 * @memberOf R
 * @since v0.8.0
 * @category Object
 * @sig ((v, k) -> Boolean) -> {k: v} -> {k: v}
 * @param {Function} pred A predicate to determine whether or not a key
 *        should be included on the output object.
 * @param {Object} obj The object to copy from
 * @return {Object} A new object with only properties that satisfy `pred`
 *         on it.
 * @see R.pick, R.filter
 * @example
 *
 *      const isUpperCase = (val, key) => key.toUpperCase() === key;
 *      R.pickBy(isUpperCase, {a: 1, b: 2, A: 3, B: 4}); //=> {A: 3, B: 4}
 */
var pickBy = _curry2(function pickBy(test, obj) {
  var result = {};
  for (var prop in obj) {
    if (test(obj[prop], prop, obj)) {
      result[prop] = obj[prop];
    }
  }
  return result;
});

/**
 * Returns the left-to-right Kleisli composition of the provided functions,
 * each of which must return a value of a type supported by [`chain`](#chain).
 *
 * `R.pipeK(f, g, h)` is equivalent to `R.pipe(f, R.chain(g), R.chain(h))`.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category Function
 * @sig Chain m => ((a -> m b), (b -> m c), ..., (y -> m z)) -> (a -> m z)
 * @param {...Function}
 * @return {Function}
 * @see R.composeK
 * @example
 *
 *      //  parseJson :: String -> Maybe *
 *      //  get :: String -> Object -> Maybe *
 *
 *      //  getStateCode :: Maybe String -> Maybe String
 *      const getStateCode = R.pipeK(
 *        parseJson,
 *        get('user'),
 *        get('address'),
 *        get('state'),
 *        R.compose(Maybe.of, R.toUpper)
 *      );
 *
 *      getStateCode('{"user":{"address":{"state":"ny"}}}');
 *      //=> Just('NY')
 *      getStateCode('[Invalid JSON]');
 *      //=> Nothing()
 * @symb R.pipeK(f, g, h)(a) = R.chain(h, R.chain(g, f(a)))
 */
function pipeK() {
  if (arguments.length === 0) {
    throw new Error('pipeK requires at least one argument');
  }
  return composeK.apply(this, reverse(arguments));
}

/**
 * Returns a new list with the given element at the front, followed by the
 * contents of the list.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig a -> [a] -> [a]
 * @param {*} el The item to add to the head of the output list.
 * @param {Array} list The array to add to the tail of the output list.
 * @return {Array} A new array.
 * @see R.append
 * @example
 *
 *      R.prepend('fee', ['fi', 'fo', 'fum']); //=> ['fee', 'fi', 'fo', 'fum']
 */
var prepend = _curry2(function prepend(el, list) {
  return _concat([el], list);
});

/**
 * Multiplies together all the elements of a list.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Math
 * @sig [Number] -> Number
 * @param {Array} list An array of numbers
 * @return {Number} The product of all the numbers in the list.
 * @see R.reduce
 * @example
 *
 *      R.product([2,4,6,8,100,1]); //=> 38400
 */
var product = reduce(multiply, 1);

/**
 * Accepts a function `fn` and a list of transformer functions and returns a
 * new curried function. When the new function is invoked, it calls the
 * function `fn` with parameters consisting of the result of calling each
 * supplied handler on successive arguments to the new function.
 *
 * If more arguments are passed to the returned function than transformer
 * functions, those arguments are passed directly to `fn` as additional
 * parameters. If you expect additional arguments that don't need to be
 * transformed, although you can ignore them, it's best to pass an identity
 * function so that the new function reports the correct arity.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig ((x1, x2, ...) -> z) -> [(a -> x1), (b -> x2), ...] -> (a -> b -> ... -> z)
 * @param {Function} fn The function to wrap.
 * @param {Array} transformers A list of transformer functions
 * @return {Function} The wrapped function.
 * @see R.converge
 * @example
 *
 *      R.useWith(Math.pow, [R.identity, R.identity])(3, 4); //=> 81
 *      R.useWith(Math.pow, [R.identity, R.identity])(3)(4); //=> 81
 *      R.useWith(Math.pow, [R.dec, R.inc])(3, 4); //=> 32
 *      R.useWith(Math.pow, [R.dec, R.inc])(3)(4); //=> 32
 * @symb R.useWith(f, [g, h])(a, b) = f(g(a), h(b))
 */
var useWith = _curry2(function useWith(fn, transformers) {
  return curryN(transformers.length, function() {
    var args = [];
    var idx = 0;
    while (idx < transformers.length) {
      args.push(transformers[idx].call(this, arguments[idx]));
      idx += 1;
    }
    return fn.apply(this, args.concat(Array.prototype.slice.call(arguments, transformers.length)));
  });
});

/**
 * Reasonable analog to SQL `select` statement.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @category Relation
 * @sig [k] -> [{k: v}] -> [{k: v}]
 * @param {Array} props The property names to project
 * @param {Array} objs The objects to query
 * @return {Array} An array of objects with just the `props` properties.
 * @example
 *
 *      const abby = {name: 'Abby', age: 7, hair: 'blond', grade: 2};
 *      const fred = {name: 'Fred', age: 12, hair: 'brown', grade: 7};
 *      const kids = [abby, fred];
 *      R.project(['name', 'grade'], kids); //=> [{name: 'Abby', grade: 2}, {name: 'Fred', grade: 7}]
 */
var project = useWith(_map, [pickAll, identity]); // passing `identity` gives correct arity

/**
 * Returns `true` if the specified object property is equal, in
 * [`R.equals`](#equals) terms, to the given value; `false` otherwise.
 * You can test multiple properties with [`R.whereEq`](#whereEq).
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig String -> a -> Object -> Boolean
 * @param {String} name
 * @param {*} val
 * @param {*} obj
 * @return {Boolean}
 * @see R.whereEq, R.propSatisfies, R.equals
 * @example
 *
 *      const abby = {name: 'Abby', age: 7, hair: 'blond'};
 *      const fred = {name: 'Fred', age: 12, hair: 'brown'};
 *      const rusty = {name: 'Rusty', age: 10, hair: 'brown'};
 *      const alois = {name: 'Alois', age: 15, disposition: 'surly'};
 *      const kids = [abby, fred, rusty, alois];
 *      const hasBrownHair = R.propEq('hair', 'brown');
 *      R.filter(hasBrownHair, kids); //=> [fred, rusty]
 */
var propEq = _curry3(function propEq(name, val, obj) {
  return equals(val, obj[name]);
});

/**
 * Returns `true` if the specified object property is of the given type;
 * `false` otherwise.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category Type
 * @sig Type -> String -> Object -> Boolean
 * @param {Function} type
 * @param {String} name
 * @param {*} obj
 * @return {Boolean}
 * @see R.is, R.propSatisfies
 * @example
 *
 *      R.propIs(Number, 'x', {x: 1, y: 2});  //=> true
 *      R.propIs(Number, 'x', {x: 'foo'});    //=> false
 *      R.propIs(Number, 'x', {});            //=> false
 */
var propIs = _curry3(function propIs(type, name, obj) {
  return is(type, obj[name]);
});

/**
 * If the given, non-null object has an own property with the specified name,
 * returns the value of that property. Otherwise returns the provided default
 * value.
 *
 * @func
 * @memberOf R
 * @since v0.6.0
 * @category Object
 * @sig a -> String -> Object -> a
 * @param {*} val The default value.
 * @param {String} p The name of the property to return.
 * @param {Object} obj The object to query.
 * @return {*} The value of given property of the supplied object or the default value.
 * @example
 *
 *      const alice = {
 *        name: 'ALICE',
 *        age: 101
 *      };
 *      const favorite = R.prop('favoriteLibrary');
 *      const favoriteWithDefault = R.propOr('Ramda', 'favoriteLibrary');
 *
 *      favorite(alice);  //=> undefined
 *      favoriteWithDefault(alice);  //=> 'Ramda'
 */
var propOr = _curry3(function propOr(val, p, obj) {
  return pathOr(val, [p], obj);
});

/**
 * Returns `true` if the specified object property satisfies the given
 * predicate; `false` otherwise. You can test multiple properties with
 * [`R.where`](#where).
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category Logic
 * @sig (a -> Boolean) -> String -> {String: a} -> Boolean
 * @param {Function} pred
 * @param {String} name
 * @param {*} obj
 * @return {Boolean}
 * @see R.where, R.propEq, R.propIs
 * @example
 *
 *      R.propSatisfies(x => x > 0, 'x', {x: 1, y: 2}); //=> true
 */
var propSatisfies = _curry3(function propSatisfies(pred, name, obj) {
  return pred(obj[name]);
});

/**
 * Acts as multiple `prop`: array of keys in, array of values out. Preserves
 * order.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Object
 * @sig [k] -> {k: v} -> [v]
 * @param {Array} ps The property names to fetch
 * @param {Object} obj The object to query
 * @return {Array} The corresponding values or partially applied function.
 * @example
 *
 *      R.props(['x', 'y'], {x: 1, y: 2}); //=> [1, 2]
 *      R.props(['c', 'a', 'b'], {b: 2, a: 1}); //=> [undefined, 1, 2]
 *
 *      const fullName = R.compose(R.join(' '), R.props(['first', 'last']));
 *      fullName({last: 'Bullet-Tooth', age: 33, first: 'Tony'}); //=> 'Tony Bullet-Tooth'
 */
var props = _curry2(function props(ps, obj) {
  var len = ps.length;
  var out = [];
  var idx = 0;

  while (idx < len) {
    out[idx] = obj[ps[idx]];
    idx += 1;
  }

  return out;
});

/**
 * Returns a list of numbers from `from` (inclusive) to `to` (exclusive).
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig Number -> Number -> [Number]
 * @param {Number} from The first number in the list.
 * @param {Number} to One more than the last number in the list.
 * @return {Array} The list of numbers in the set `[a, b)`.
 * @example
 *
 *      R.range(1, 5);    //=> [1, 2, 3, 4]
 *      R.range(50, 53);  //=> [50, 51, 52]
 */
var range = _curry2(function range(from, to) {
  if (!(_isNumber(from) && _isNumber(to))) {
    throw new TypeError('Both arguments to range must be numbers');
  }
  var result = [];
  var n = from;
  while (n < to) {
    result.push(n);
    n += 1;
  }
  return result;
});

/**
 * Returns a single item by iterating through the list, successively calling
 * the iterator function and passing it an accumulator value and the current
 * value from the array, and then passing the result to the next call.
 *
 * Similar to [`reduce`](#reduce), except moves through the input list from the
 * right to the left.
 *
 * The iterator function receives two values: *(value, acc)*, while the arguments'
 * order of `reduce`'s iterator function is *(acc, value)*.
 *
 * Note: `R.reduceRight` does not skip deleted or unassigned indices (sparse
 * arrays), unlike the native `Array.prototype.reduceRight` method. For more details
 * on this behavior, see:
 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduceRight#Description
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig ((a, b) -> b) -> b -> [a] -> b
 * @param {Function} fn The iterator function. Receives two values, the current element from the array
 *        and the accumulator.
 * @param {*} acc The accumulator value.
 * @param {Array} list The list to iterate over.
 * @return {*} The final, accumulated value.
 * @see R.reduce, R.addIndex
 * @example
 *
 *      R.reduceRight(R.subtract, 0, [1, 2, 3, 4]) // => (1 - (2 - (3 - (4 - 0)))) = -2
 *      //    -               -2
 *      //   / \              / \
 *      //  1   -            1   3
 *      //     / \              / \
 *      //    2   -     ==>    2  -1
 *      //       / \              / \
 *      //      3   -            3   4
 *      //         / \              / \
 *      //        4   0            4   0
 *
 * @symb R.reduceRight(f, a, [b, c, d]) = f(b, f(c, f(d, a)))
 */
var reduceRight = _curry3(function reduceRight(fn, acc, list) {
  var idx = list.length - 1;
  while (idx >= 0) {
    acc = fn(list[idx], acc);
    idx -= 1;
  }
  return acc;
});

/**
 * Like [`reduce`](#reduce), `reduceWhile` returns a single item by iterating
 * through the list, successively calling the iterator function. `reduceWhile`
 * also takes a predicate that is evaluated before each step. If the predicate
 * returns `false`, it "short-circuits" the iteration and returns the current
 * value of the accumulator.
 *
 * @func
 * @memberOf R
 * @since v0.22.0
 * @category List
 * @sig ((a, b) -> Boolean) -> ((a, b) -> a) -> a -> [b] -> a
 * @param {Function} pred The predicate. It is passed the accumulator and the
 *        current element.
 * @param {Function} fn The iterator function. Receives two values, the
 *        accumulator and the current element.
 * @param {*} a The accumulator value.
 * @param {Array} list The list to iterate over.
 * @return {*} The final, accumulated value.
 * @see R.reduce, R.reduced
 * @example
 *
 *      const isOdd = (acc, x) => x % 2 === 1;
 *      const xs = [1, 3, 5, 60, 777, 800];
 *      R.reduceWhile(isOdd, R.add, 0, xs); //=> 9
 *
 *      const ys = [2, 4, 6]
 *      R.reduceWhile(isOdd, R.add, 111, ys); //=> 111
 */
var reduceWhile = _curryN(4, [], function _reduceWhile(pred, fn, a, list) {
  return _reduce(function(acc, x) {
    return pred(acc, x) ? fn(acc, x) : _reduced(acc);
  }, a, list);
});

/**
 * Returns a value wrapped to indicate that it is the final value of the reduce
 * and transduce functions. The returned value should be considered a black
 * box: the internal structure is not guaranteed to be stable.
 *
 * Note: this optimization is only available to the below functions:
 * - [`reduce`](#reduce)
 * - [`reduceWhile`](#reduceWhile)
 * - [`transduce`](#transduce)
 *
 * @func
 * @memberOf R
 * @since v0.15.0
 * @category List
 * @sig a -> *
 * @param {*} x The final value of the reduce.
 * @return {*} The wrapped value.
 * @see R.reduce, R.reduceWhile, R.transduce
 * @example
 *
 *     R.reduce(
 *       (acc, item) => item > 3 ? R.reduced(acc) : acc.concat(item),
 *       [],
 *       [1, 2, 3, 4, 5]) // [1, 2, 3]
 */
var reduced = _curry1(_reduced);

/**
 * Calls an input function `n` times, returning an array containing the results
 * of those function calls.
 *
 * `fn` is passed one argument: The current value of `n`, which begins at `0`
 * and is gradually incremented to `n - 1`.
 *
 * @func
 * @memberOf R
 * @since v0.2.3
 * @category List
 * @sig (Number -> a) -> Number -> [a]
 * @param {Function} fn The function to invoke. Passed one argument, the current value of `n`.
 * @param {Number} n A value between `0` and `n - 1`. Increments after each function call.
 * @return {Array} An array containing the return values of all calls to `fn`.
 * @see R.repeat
 * @example
 *
 *      R.times(R.identity, 5); //=> [0, 1, 2, 3, 4]
 * @symb R.times(f, 0) = []
 * @symb R.times(f, 1) = [f(0)]
 * @symb R.times(f, 2) = [f(0), f(1)]
 */
var times = _curry2(function times(fn, n) {
  var len = Number(n);
  var idx = 0;
  var list;

  if (len < 0 || isNaN(len)) {
    throw new RangeError('n must be a non-negative number');
  }
  list = new Array(len);
  while (idx < len) {
    list[idx] = fn(idx);
    idx += 1;
  }
  return list;
});

/**
 * Returns a fixed list of size `n` containing a specified identical value.
 *
 * @func
 * @memberOf R
 * @since v0.1.1
 * @category List
 * @sig a -> n -> [a]
 * @param {*} value The value to repeat.
 * @param {Number} n The desired size of the output list.
 * @return {Array} A new array containing `n` `value`s.
 * @see R.times
 * @example
 *
 *      R.repeat('hi', 5); //=> ['hi', 'hi', 'hi', 'hi', 'hi']
 *
 *      const obj = {};
 *      const repeatedObjs = R.repeat(obj, 5); //=> [{}, {}, {}, {}, {}]
 *      repeatedObjs[0] === repeatedObjs[1]; //=> true
 * @symb R.repeat(a, 0) = []
 * @symb R.repeat(a, 1) = [a]
 * @symb R.repeat(a, 2) = [a, a]
 */
var repeat = _curry2(function repeat(value, n) {
  return times(always(value), n);
});

/**
 * Replace a substring or regex match in a string with a replacement.
 *
 * The first two parameters correspond to the parameters of the
 * `String.prototype.replace()` function, so the second parameter can also be a
 * function.
 *
 * @func
 * @memberOf R
 * @since v0.7.0
 * @category String
 * @sig RegExp|String -> String -> String -> String
 * @param {RegExp|String} pattern A regular expression or a substring to match.
 * @param {String} replacement The string to replace the matches with.
 * @param {String} str The String to do the search and replacement in.
 * @return {String} The result.
 * @example
 *
 *      R.replace('foo', 'bar', 'foo foo foo'); //=> 'bar foo foo'
 *      R.replace(/foo/, 'bar', 'foo foo foo'); //=> 'bar foo foo'
 *
 *      // Use the "g" (global) flag to replace all occurrences:
 *      R.replace(/foo/g, 'bar', 'foo foo foo'); //=> 'bar bar bar'
 */
var replace = _curry3(function replace(regex, replacement, str) {
  return str.replace(regex, replacement);
});

/**
 * Scan is similar to [`reduce`](#reduce), but returns a list of successively
 * reduced values from the left
 *
 * @func
 * @memberOf R
 * @since v0.10.0
 * @category List
 * @sig ((a, b) -> a) -> a -> [b] -> [a]
 * @param {Function} fn The iterator function. Receives two values, the accumulator and the
 *        current element from the array
 * @param {*} acc The accumulator value.
 * @param {Array} list The list to iterate over.
 * @return {Array} A list of all intermediately reduced values.
 * @see R.reduce, R.mapAccum
 * @example
 *
 *      const numbers = [1, 2, 3, 4];
 *      const factorials = R.scan(R.multiply, 1, numbers); //=> [1, 1, 2, 6, 24]
 * @symb R.scan(f, a, [b, c]) = [a, f(a, b), f(f(a, b), c)]
 */
var scan = _curry3(function scan(fn, acc, list) {
  var idx = 0;
  var len = list.length;
  var result = [acc];
  while (idx < len) {
    acc = fn(acc, list[idx]);
    result[idx + 1] = acc;
    idx += 1;
  }
  return result;
});

/**
 * Transforms a [Traversable](https://github.com/fantasyland/fantasy-land#traversable)
 * of [Applicative](https://github.com/fantasyland/fantasy-land#applicative) into an
 * Applicative of Traversable.
 *
 * Dispatches to the `sequence` method of the second argument, if present.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category List
 * @sig (Applicative f, Traversable t) => (a -> f a) -> t (f a) -> f (t a)
 * @param {Function} of
 * @param {*} traversable
 * @return {*}
 * @see R.traverse
 * @example
 *
 *      R.sequence(Maybe.of, [Just(1), Just(2), Just(3)]);   //=> Just([1, 2, 3])
 *      R.sequence(Maybe.of, [Just(1), Just(2), Nothing()]); //=> Nothing()
 *
 *      R.sequence(R.of, Just([1, 2, 3])); //=> [Just(1), Just(2), Just(3)]
 *      R.sequence(R.of, Nothing());       //=> [Nothing()]
 */
var sequence = _curry2(function sequence(of, traversable) {
  return typeof traversable.sequence === 'function' ?
    traversable.sequence(of) :
    reduceRight(function(x, acc) { return ap(map(prepend, x), acc); },
                of([]),
                traversable);
});

/**
 * Returns the result of "setting" the portion of the given data structure
 * focused by the given lens to the given value.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category Object
 * @typedefn Lens s a = Functor f => (a -> f a) -> s -> f s
 * @sig Lens s a -> a -> s -> s
 * @param {Lens} lens
 * @param {*} v
 * @param {*} x
 * @return {*}
 * @see R.prop, R.lensIndex, R.lensProp
 * @example
 *
 *      const xLens = R.lensProp('x');
 *
 *      R.set(xLens, 4, {x: 1, y: 2});  //=> {x: 4, y: 2}
 *      R.set(xLens, 8, {x: 1, y: 2});  //=> {x: 8, y: 2}
 */
var set = _curry3(function set(lens, v, x) {
  return over(lens, always(v), x);
});

/**
 * Returns a copy of the list, sorted according to the comparator function,
 * which should accept two values at a time and return a negative number if the
 * first value is smaller, a positive number if it's larger, and zero if they
 * are equal. Please note that this is a **copy** of the list. It does not
 * modify the original.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig ((a, a) -> Number) -> [a] -> [a]
 * @param {Function} comparator A sorting function :: a -> b -> Int
 * @param {Array} list The list to sort
 * @return {Array} a new array with its elements sorted by the comparator function.
 * @example
 *
 *      const diff = function(a, b) { return a - b; };
 *      R.sort(diff, [4,2,7,5]); //=> [2, 4, 5, 7]
 */
var sort = _curry2(function sort(comparator, list) {
  return Array.prototype.slice.call(list, 0).sort(comparator);
});

/**
 * Sorts the list according to the supplied function.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig Ord b => (a -> b) -> [a] -> [a]
 * @param {Function} fn
 * @param {Array} list The list to sort.
 * @return {Array} A new list sorted by the keys generated by `fn`.
 * @example
 *
 *      const sortByFirstItem = R.sortBy(R.prop(0));
 *      const pairs = [[-1, 1], [-2, 2], [-3, 3]];
 *      sortByFirstItem(pairs); //=> [[-3, 3], [-2, 2], [-1, 1]]
 *
 *      const sortByNameCaseInsensitive = R.sortBy(R.compose(R.toLower, R.prop('name')));
 *      const alice = {
 *        name: 'ALICE',
 *        age: 101
 *      };
 *      const bob = {
 *        name: 'Bob',
 *        age: -10
 *      };
 *      const clara = {
 *        name: 'clara',
 *        age: 314.159
 *      };
 *      const people = [clara, bob, alice];
 *      sortByNameCaseInsensitive(people); //=> [alice, bob, clara]
 */
var sortBy = _curry2(function sortBy(fn, list) {
  return Array.prototype.slice.call(list, 0).sort(function(a, b) {
    var aa = fn(a);
    var bb = fn(b);
    return aa < bb ? -1 : aa > bb ? 1 : 0;
  });
});

/**
 * Sorts a list according to a list of comparators.
 *
 * @func
 * @memberOf R
 * @since v0.23.0
 * @category Relation
 * @sig [(a, a) -> Number] -> [a] -> [a]
 * @param {Array} functions A list of comparator functions.
 * @param {Array} list The list to sort.
 * @return {Array} A new list sorted according to the comarator functions.
 * @example
 *
 *      const alice = {
 *        name: 'alice',
 *        age: 40
 *      };
 *      const bob = {
 *        name: 'bob',
 *        age: 30
 *      };
 *      const clara = {
 *        name: 'clara',
 *        age: 40
 *      };
 *      const people = [clara, bob, alice];
 *      const ageNameSort = R.sortWith([
 *        R.descend(R.prop('age')),
 *        R.ascend(R.prop('name'))
 *      ]);
 *      ageNameSort(people); //=> [alice, clara, bob]
 */
var sortWith = _curry2(function sortWith(fns, list) {
  return Array.prototype.slice.call(list, 0).sort(function(a, b) {
    var result = 0;
    var i = 0;
    while (result === 0 && i < fns.length) {
      result = fns[i](a, b);
      i += 1;
    }
    return result;
  });
});

/**
 * Splits a string into an array of strings based on the given
 * separator.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category String
 * @sig (String | RegExp) -> String -> [String]
 * @param {String|RegExp} sep The pattern.
 * @param {String} str The string to separate into an array.
 * @return {Array} The array of strings from `str` separated by `str`.
 * @see R.join
 * @example
 *
 *      const pathComponents = R.split('/');
 *      R.tail(pathComponents('/usr/local/bin/node')); //=> ['usr', 'local', 'bin', 'node']
 *
 *      R.split('.', 'a.b.c.xyz.d'); //=> ['a', 'b', 'c', 'xyz', 'd']
 */
var split = invoker(1, 'split');

/**
 * Splits a given list or string at a given index.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category List
 * @sig Number -> [a] -> [[a], [a]]
 * @sig Number -> String -> [String, String]
 * @param {Number} index The index where the array/string is split.
 * @param {Array|String} array The array/string to be split.
 * @return {Array}
 * @example
 *
 *      R.splitAt(1, [1, 2, 3]);          //=> [[1], [2, 3]]
 *      R.splitAt(5, 'hello world');      //=> ['hello', ' world']
 *      R.splitAt(-1, 'foobar');          //=> ['fooba', 'r']
 */
var splitAt = _curry2(function splitAt(index, array) {
  return [slice(0, index, array), slice(index, length(array), array)];
});

/**
 * Splits a collection into slices of the specified length.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category List
 * @sig Number -> [a] -> [[a]]
 * @sig Number -> String -> [String]
 * @param {Number} n
 * @param {Array} list
 * @return {Array}
 * @example
 *
 *      R.splitEvery(3, [1, 2, 3, 4, 5, 6, 7]); //=> [[1, 2, 3], [4, 5, 6], [7]]
 *      R.splitEvery(3, 'foobarbaz'); //=> ['foo', 'bar', 'baz']
 */
var splitEvery = _curry2(function splitEvery(n, list) {
  if (n <= 0) {
    throw new Error('First argument to splitEvery must be a positive integer');
  }
  var result = [];
  var idx = 0;
  while (idx < list.length) {
    result.push(slice(idx, idx += n, list));
  }
  return result;
});

/**
 * Takes a list and a predicate and returns a pair of lists with the following properties:
 *
 *  - the result of concatenating the two output lists is equivalent to the input list;
 *  - none of the elements of the first output list satisfies the predicate; and
 *  - if the second output list is non-empty, its first element satisfies the predicate.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category List
 * @sig (a -> Boolean) -> [a] -> [[a], [a]]
 * @param {Function} pred The predicate that determines where the array is split.
 * @param {Array} list The array to be split.
 * @return {Array}
 * @example
 *
 *      R.splitWhen(R.equals(2), [1, 2, 3, 1, 2, 3]);   //=> [[1], [2, 3, 1, 2, 3]]
 */
var splitWhen = _curry2(function splitWhen(pred, list) {
  var idx = 0;
  var len = list.length;
  var prefix = [];

  while (idx < len && !pred(list[idx])) {
    prefix.push(list[idx]);
    idx += 1;
  }

  return [prefix, Array.prototype.slice.call(list, idx)];
});

/**
 * Checks if a list starts with the provided sublist.
 *
 * Similarly, checks if a string starts with the provided substring.
 *
 * @func
 * @memberOf R
 * @since v0.24.0
 * @category List
 * @sig [a] -> [a] -> Boolean
 * @sig String -> String -> Boolean
 * @param {*} prefix
 * @param {*} list
 * @return {Boolean}
 * @see R.endsWith
 * @example
 *
 *      R.startsWith('a', 'abc')                //=> true
 *      R.startsWith('b', 'abc')                //=> false
 *      R.startsWith(['a'], ['a', 'b', 'c'])    //=> true
 *      R.startsWith(['b'], ['a', 'b', 'c'])    //=> false
 */
var startsWith = _curry2(function(prefix, list) {
  return equals(take(prefix.length, list), prefix);
});

/**
 * Subtracts its second argument from its first argument.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Math
 * @sig Number -> Number -> Number
 * @param {Number} a The first value.
 * @param {Number} b The second value.
 * @return {Number} The result of `a - b`.
 * @see R.add
 * @example
 *
 *      R.subtract(10, 8); //=> 2
 *
 *      const minus5 = R.subtract(R.__, 5);
 *      minus5(17); //=> 12
 *
 *      const complementaryAngle = R.subtract(90);
 *      complementaryAngle(30); //=> 60
 *      complementaryAngle(72); //=> 18
 */
var subtract = _curry2(function subtract(a, b) {
  return Number(a) - Number(b);
});

/**
 * Finds the set (i.e. no duplicates) of all elements contained in the first or
 * second list, but not both.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category Relation
 * @sig [*] -> [*] -> [*]
 * @param {Array} list1 The first list.
 * @param {Array} list2 The second list.
 * @return {Array} The elements in `list1` or `list2`, but not both.
 * @see R.symmetricDifferenceWith, R.difference, R.differenceWith
 * @example
 *
 *      R.symmetricDifference([1,2,3,4], [7,6,5,4,3]); //=> [1,2,7,6,5]
 *      R.symmetricDifference([7,6,5,4,3], [1,2,3,4]); //=> [7,6,5,1,2]
 */
var symmetricDifference = _curry2(function symmetricDifference(list1, list2) {
  return concat(difference(list1, list2), difference(list2, list1));
});

/**
 * Finds the set (i.e. no duplicates) of all elements contained in the first or
 * second list, but not both. Duplication is determined according to the value
 * returned by applying the supplied predicate to two list elements.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category Relation
 * @sig ((a, a) -> Boolean) -> [a] -> [a] -> [a]
 * @param {Function} pred A predicate used to test whether two items are equal.
 * @param {Array} list1 The first list.
 * @param {Array} list2 The second list.
 * @return {Array} The elements in `list1` or `list2`, but not both.
 * @see R.symmetricDifference, R.difference, R.differenceWith
 * @example
 *
 *      const eqA = R.eqBy(R.prop('a'));
 *      const l1 = [{a: 1}, {a: 2}, {a: 3}, {a: 4}];
 *      const l2 = [{a: 3}, {a: 4}, {a: 5}, {a: 6}];
 *      R.symmetricDifferenceWith(eqA, l1, l2); //=> [{a: 1}, {a: 2}, {a: 5}, {a: 6}]
 */
var symmetricDifferenceWith = _curry3(function symmetricDifferenceWith(pred, list1, list2) {
  return concat(differenceWith(pred, list1, list2), differenceWith(pred, list2, list1));
});

/**
 * Returns a new list containing the last `n` elements of a given list, passing
 * each value to the supplied predicate function, and terminating when the
 * predicate function returns `false`. Excludes the element that caused the
 * predicate function to fail. The predicate function is passed one argument:
 * *(value)*.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category List
 * @sig (a -> Boolean) -> [a] -> [a]
 * @sig (a -> Boolean) -> String -> String
 * @param {Function} fn The function called per iteration.
 * @param {Array} xs The collection to iterate over.
 * @return {Array} A new array.
 * @see R.dropLastWhile, R.addIndex
 * @example
 *
 *      const isNotOne = x => x !== 1;
 *
 *      R.takeLastWhile(isNotOne, [1, 2, 3, 4]); //=> [2, 3, 4]
 *
 *      R.takeLastWhile(x => x !== 'R' , 'Ramda'); //=> 'amda'
 */
var takeLastWhile = _curry2(function takeLastWhile(fn, xs) {
  var idx = xs.length - 1;
  while (idx >= 0 && fn(xs[idx])) {
    idx -= 1;
  }
  return slice(idx + 1, Infinity, xs);
});

function XTakeWhile(f, xf) {
  this.xf = xf;
  this.f = f;
}
XTakeWhile.prototype['@@transducer/init'] = _xfBase.init;
XTakeWhile.prototype['@@transducer/result'] = _xfBase.result;
XTakeWhile.prototype['@@transducer/step'] = function(result, input) {
  return this.f(input) ? this.xf['@@transducer/step'](result, input) : _reduced(result);
};

var _xtakeWhile = _curry2(function _xtakeWhile(f, xf) { return new XTakeWhile(f, xf); });

/**
 * Returns a new list containing the first `n` elements of a given list,
 * passing each value to the supplied predicate function, and terminating when
 * the predicate function returns `false`. Excludes the element that caused the
 * predicate function to fail. The predicate function is passed one argument:
 * *(value)*.
 *
 * Dispatches to the `takeWhile` method of the second argument, if present.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig (a -> Boolean) -> [a] -> [a]
 * @sig (a -> Boolean) -> String -> String
 * @param {Function} fn The function called per iteration.
 * @param {Array} xs The collection to iterate over.
 * @return {Array} A new array.
 * @see R.dropWhile, R.transduce, R.addIndex
 * @example
 *
 *      const isNotFour = x => x !== 4;
 *
 *      R.takeWhile(isNotFour, [1, 2, 3, 4, 3, 2, 1]); //=> [1, 2, 3]
 *
 *      R.takeWhile(x => x !== 'd' , 'Ramda'); //=> 'Ram'
 */
var takeWhile = _curry2(_dispatchable(['takeWhile'], _xtakeWhile, function takeWhile(fn, xs) {
  var idx = 0;
  var len = xs.length;
  while (idx < len && fn(xs[idx])) {
    idx += 1;
  }
  return slice(0, idx, xs);
}));

function XTap(f, xf) {
  this.xf = xf;
  this.f = f;
}
XTap.prototype['@@transducer/init'] = _xfBase.init;
XTap.prototype['@@transducer/result'] = _xfBase.result;
XTap.prototype['@@transducer/step'] = function(result, input) {
  this.f(input);
  return this.xf['@@transducer/step'](result, input);
};

var _xtap = _curry2(function _xtap(f, xf) { return new XTap(f, xf); });

/**
 * Runs the given function with the supplied object, then returns the object.
 *
 * Acts as a transducer if a transformer is given as second parameter.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Function
 * @sig (a -> *) -> a -> a
 * @param {Function} fn The function to call with `x`. The return value of `fn` will be thrown away.
 * @param {*} x
 * @return {*} `x`.
 * @example
 *
 *      const sayX = x => console.log('x is ' + x);
 *      R.tap(sayX, 100); //=> 100
 *      // logs 'x is 100'
 * @symb R.tap(f, a) = a
 */
var tap = _curry2(_dispatchable([], _xtap, function tap(fn, x) {
  fn(x);
  return x;
}));

function _isRegExp(x) {
  return Object.prototype.toString.call(x) === '[object RegExp]';
}

/**
 * Determines whether a given string matches a given regular expression.
 *
 * @func
 * @memberOf R
 * @since v0.12.0
 * @category String
 * @sig RegExp -> String -> Boolean
 * @param {RegExp} pattern
 * @param {String} str
 * @return {Boolean}
 * @see R.match
 * @example
 *
 *      R.test(/^x/, 'xyz'); //=> true
 *      R.test(/^y/, 'xyz'); //=> false
 */
var test = _curry2(function test(pattern, str) {
  if (!_isRegExp(pattern)) {
    throw new TypeError('‘test’ requires a value of type RegExp as its first argument; received ' + toString$1(pattern));
  }
  return _cloneRegExp(pattern).test(str);
});

/**
 * Returns the result of applying the onSuccess function to the value inside
 * a successfully resolved promise. This is useful for working with promises
 * inside function compositions.
 *
 * @func
 * @memberOf R
 * @category Function
 * @sig (a -> b) -> (Promise e a) -> (Promise e b)
 * @sig (a -> (Promise e b)) -> (Promise e a) -> (Promise e b)
 * @param {Function} onSuccess The function to apply. Can return a value or a promise of a value.
 * @param {Promise} p
 * @return {Promise} The result of calling `p.then(onSuccess)`
 * @see R.otherwise
 * @example
 *
 *      var makeQuery = (email) => ({ query: { email }});
 *
 *      //getMemberName :: String -> Promise ({firstName, lastName})
 *      var getMemberName = R.pipe(
 *        makeQuery,
 *        fetchMember,
 *        R.then(R.pick(['firstName', 'lastName']))
 *      );
 */
const then = _curry2(function then(f, p) {
  _assertPromise('then', p);

  return p.then(f);
});

/**
 * The lower case version of a string.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category String
 * @sig String -> String
 * @param {String} str The string to lower case.
 * @return {String} The lower case version of `str`.
 * @see R.toUpper
 * @example
 *
 *      R.toLower('XYZ'); //=> 'xyz'
 */
var toLower = invoker(0, 'toLowerCase');

/**
 * Converts an object into an array of key, value arrays. Only the object's
 * own properties are used.
 * Note that the order of the output array is not guaranteed to be consistent
 * across different JS platforms.
 *
 * @func
 * @memberOf R
 * @since v0.4.0
 * @category Object
 * @sig {String: *} -> [[String,*]]
 * @param {Object} obj The object to extract from
 * @return {Array} An array of key, value arrays from the object's own properties.
 * @see R.fromPairs
 * @example
 *
 *      R.toPairs({a: 1, b: 2, c: 3}); //=> [['a', 1], ['b', 2], ['c', 3]]
 */
var toPairs = _curry1(function toPairs(obj) {
  var pairs = [];
  for (var prop in obj) {
    if (_has(prop, obj)) {
      pairs[pairs.length] = [prop, obj[prop]];
    }
  }
  return pairs;
});

/**
 * Converts an object into an array of key, value arrays. The object's own
 * properties and prototype properties are used. Note that the order of the
 * output array is not guaranteed to be consistent across different JS
 * platforms.
 *
 * @func
 * @memberOf R
 * @since v0.4.0
 * @category Object
 * @sig {String: *} -> [[String,*]]
 * @param {Object} obj The object to extract from
 * @return {Array} An array of key, value arrays from the object's own
 *         and prototype properties.
 * @example
 *
 *      const F = function() { this.x = 'X'; };
 *      F.prototype.y = 'Y';
 *      const f = new F();
 *      R.toPairsIn(f); //=> [['x','X'], ['y','Y']]
 */
var toPairsIn = _curry1(function toPairsIn(obj) {
  var pairs = [];
  for (var prop in obj) {
    pairs[pairs.length] = [prop, obj[prop]];
  }
  return pairs;
});

/**
 * The upper case version of a string.
 *
 * @func
 * @memberOf R
 * @since v0.9.0
 * @category String
 * @sig String -> String
 * @param {String} str The string to upper case.
 * @return {String} The upper case version of `str`.
 * @see R.toLower
 * @example
 *
 *      R.toUpper('abc'); //=> 'ABC'
 */
var toUpper = invoker(0, 'toUpperCase');

/**
 * Initializes a transducer using supplied iterator function. Returns a single
 * item by iterating through the list, successively calling the transformed
 * iterator function and passing it an accumulator value and the current value
 * from the array, and then passing the result to the next call.
 *
 * The iterator function receives two values: *(acc, value)*. It will be
 * wrapped as a transformer to initialize the transducer. A transformer can be
 * passed directly in place of an iterator function. In both cases, iteration
 * may be stopped early with the [`R.reduced`](#reduced) function.
 *
 * A transducer is a function that accepts a transformer and returns a
 * transformer and can be composed directly.
 *
 * A transformer is an an object that provides a 2-arity reducing iterator
 * function, step, 0-arity initial value function, init, and 1-arity result
 * extraction function, result. The step function is used as the iterator
 * function in reduce. The result function is used to convert the final
 * accumulator into the return type and in most cases is
 * [`R.identity`](#identity). The init function can be used to provide an
 * initial accumulator, but is ignored by transduce.
 *
 * The iteration is performed with [`R.reduce`](#reduce) after initializing the transducer.
 *
 * @func
 * @memberOf R
 * @since v0.12.0
 * @category List
 * @sig (c -> c) -> ((a, b) -> a) -> a -> [b] -> a
 * @param {Function} xf The transducer function. Receives a transformer and returns a transformer.
 * @param {Function} fn The iterator function. Receives two values, the accumulator and the
 *        current element from the array. Wrapped as transformer, if necessary, and used to
 *        initialize the transducer
 * @param {*} acc The initial accumulator value.
 * @param {Array} list The list to iterate over.
 * @return {*} The final, accumulated value.
 * @see R.reduce, R.reduced, R.into
 * @example
 *
 *      const numbers = [1, 2, 3, 4];
 *      const transducer = R.compose(R.map(R.add(1)), R.take(2));
 *      R.transduce(transducer, R.flip(R.append), [], numbers); //=> [2, 3]
 *
 *      const isOdd = (x) => x % 2 === 1;
 *      const firstOddTransducer = R.compose(R.filter(isOdd), R.take(1));
 *      R.transduce(firstOddTransducer, R.flip(R.append), [], R.range(0, 100)); //=> [1]
 */
var transduce = curryN(4, function transduce(xf, fn, acc, list) {
  return _reduce(xf(typeof fn === 'function' ? _xwrap(fn) : fn), acc, list);
});

/**
 * Transposes the rows and columns of a 2D list.
 * When passed a list of `n` lists of length `x`,
 * returns a list of `x` lists of length `n`.
 *
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category List
 * @sig [[a]] -> [[a]]
 * @param {Array} list A 2D list
 * @return {Array} A 2D list
 * @example
 *
 *      R.transpose([[1, 'a'], [2, 'b'], [3, 'c']]) //=> [[1, 2, 3], ['a', 'b', 'c']]
 *      R.transpose([[1, 2, 3], ['a', 'b', 'c']]) //=> [[1, 'a'], [2, 'b'], [3, 'c']]
 *
 *      // If some of the rows are shorter than the following rows, their elements are skipped:
 *      R.transpose([[10, 11], [20], [], [30, 31, 32]]) //=> [[10, 20, 30], [11, 31], [32]]
 * @symb R.transpose([[a], [b], [c]]) = [a, b, c]
 * @symb R.transpose([[a, b], [c, d]]) = [[a, c], [b, d]]
 * @symb R.transpose([[a, b], [c]]) = [[a, c], [b]]
 */
var transpose = _curry1(function transpose(outerlist) {
  var i = 0;
  var result = [];
  while (i < outerlist.length) {
    var innerlist = outerlist[i];
    var j = 0;
    while (j < innerlist.length) {
      if (typeof result[j] === 'undefined') {
        result[j] = [];
      }
      result[j].push(innerlist[j]);
      j += 1;
    }
    i += 1;
  }
  return result;
});

/**
 * Maps an [Applicative](https://github.com/fantasyland/fantasy-land#applicative)-returning
 * function over a [Traversable](https://github.com/fantasyland/fantasy-land#traversable),
 * then uses [`sequence`](#sequence) to transform the resulting Traversable of Applicative
 * into an Applicative of Traversable.
 *
 * Dispatches to the `traverse` method of the third argument, if present.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category List
 * @sig (Applicative f, Traversable t) => (a -> f a) -> (a -> f b) -> t a -> f (t b)
 * @param {Function} of
 * @param {Function} f
 * @param {*} traversable
 * @return {*}
 * @see R.sequence
 * @example
 *
 *      // Returns `Maybe.Nothing` if the given divisor is `0`
 *      const safeDiv = n => d => d === 0 ? Maybe.Nothing() : Maybe.Just(n / d)
 *
 *      R.traverse(Maybe.of, safeDiv(10), [2, 4, 5]); //=> Maybe.Just([5, 2.5, 2])
 *      R.traverse(Maybe.of, safeDiv(10), [2, 0, 5]); //=> Maybe.Nothing
 */
var traverse = _curry3(function traverse(of, f, traversable) {
  return typeof traversable['fantasy-land/traverse'] === 'function' ?
    traversable['fantasy-land/traverse'](f, of) :
    sequence(of, map(f, traversable));
});

var ws = '\x09\x0A\x0B\x0C\x0D\x20\xA0\u1680\u180E\u2000\u2001\u2002\u2003' +
         '\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u202F\u205F\u3000\u2028' +
         '\u2029\uFEFF';
var zeroWidth = '\u200b';
var hasProtoTrim = (typeof String.prototype.trim === 'function');
/**
 * Removes (strips) whitespace from both ends of the string.
 *
 * @func
 * @memberOf R
 * @since v0.6.0
 * @category String
 * @sig String -> String
 * @param {String} str The string to trim.
 * @return {String} Trimmed version of `str`.
 * @example
 *
 *      R.trim('   xyz  '); //=> 'xyz'
 *      R.map(R.trim, R.split(',', 'x, y, z')); //=> ['x', 'y', 'z']
 */
var trim = !hasProtoTrim || (ws.trim() || !zeroWidth.trim()) ?
  _curry1(function trim(str) {
    var beginRx = new RegExp('^[' + ws + '][' + ws + ']*');
    var endRx = new RegExp('[' + ws + '][' + ws + ']*$');
    return str.replace(beginRx, '').replace(endRx, '');
  }) :
  _curry1(function trim(str) {
    return str.trim();
  });

/**
 * `tryCatch` takes two functions, a `tryer` and a `catcher`. The returned
 * function evaluates the `tryer`; if it does not throw, it simply returns the
 * result. If the `tryer` *does* throw, the returned function evaluates the
 * `catcher` function and returns its result. Note that for effective
 * composition with this function, both the `tryer` and `catcher` functions
 * must return the same type of results.
 *
 * @func
 * @memberOf R
 * @since v0.20.0
 * @category Function
 * @sig (...x -> a) -> ((e, ...x) -> a) -> (...x -> a)
 * @param {Function} tryer The function that may throw.
 * @param {Function} catcher The function that will be evaluated if `tryer` throws.
 * @return {Function} A new function that will catch exceptions and send then to the catcher.
 * @example
 *
 *      R.tryCatch(R.prop('x'), R.F)({x: true}); //=> true
 *      R.tryCatch(() => { throw 'foo'}, R.always('catched'))('bar') // => 'catched'
 *      R.tryCatch(R.times(R.identity), R.always([]))('s') // => []
 `` */
var tryCatch = _curry2(function _tryCatch(tryer, catcher) {
  return _arity(tryer.length, function() {
    try {
      return tryer.apply(this, arguments);
    } catch (e) {
      return catcher.apply(this, _concat([e], arguments));
    }
  });
});

/**
 * Takes a function `fn`, which takes a single array argument, and returns a
 * function which:
 *
 *   - takes any number of positional arguments;
 *   - passes these arguments to `fn` as an array; and
 *   - returns the result.
 *
 * In other words, `R.unapply` derives a variadic function from a function which
 * takes an array. `R.unapply` is the inverse of [`R.apply`](#apply).
 *
 * @func
 * @memberOf R
 * @since v0.8.0
 * @category Function
 * @sig ([*...] -> a) -> (*... -> a)
 * @param {Function} fn
 * @return {Function}
 * @see R.apply
 * @example
 *
 *      R.unapply(JSON.stringify)(1, 2, 3); //=> '[1,2,3]'
 * @symb R.unapply(f)(a, b) = f([a, b])
 */
var unapply = _curry1(function unapply(fn) {
  return function() {
    return fn(Array.prototype.slice.call(arguments, 0));
  };
});

/**
 * Wraps a function of any arity (including nullary) in a function that accepts
 * exactly 1 parameter. Any extraneous parameters will not be passed to the
 * supplied function.
 *
 * @func
 * @memberOf R
 * @since v0.2.0
 * @category Function
 * @sig (* -> b) -> (a -> b)
 * @param {Function} fn The function to wrap.
 * @return {Function} A new function wrapping `fn`. The new function is guaranteed to be of
 *         arity 1.
 * @see R.binary, R.nAry
 * @example
 *
 *      const takesTwoArgs = function(a, b) {
 *        return [a, b];
 *      };
 *      takesTwoArgs.length; //=> 2
 *      takesTwoArgs(1, 2); //=> [1, 2]
 *
 *      const takesOneArg = R.unary(takesTwoArgs);
 *      takesOneArg.length; //=> 1
 *      // Only 1 argument is passed to the wrapped function
 *      takesOneArg(1, 2); //=> [1, undefined]
 * @symb R.unary(f)(a, b, c) = f(a)
 */
var unary = _curry1(function unary(fn) {
  return nAry(1, fn);
});

/**
 * Returns a function of arity `n` from a (manually) curried function.
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category Function
 * @sig Number -> (a -> b) -> (a -> c)
 * @param {Number} length The arity for the returned function.
 * @param {Function} fn The function to uncurry.
 * @return {Function} A new function.
 * @see R.curry
 * @example
 *
 *      const addFour = a => b => c => d => a + b + c + d;
 *
 *      const uncurriedAddFour = R.uncurryN(4, addFour);
 *      uncurriedAddFour(1, 2, 3, 4); //=> 10
 */
var uncurryN = _curry2(function uncurryN(depth, fn) {
  return curryN(depth, function() {
    var currentDepth = 1;
    var value = fn;
    var idx = 0;
    var endIdx;
    while (currentDepth <= depth && typeof value === 'function') {
      endIdx = currentDepth === depth ? arguments.length : idx + value.length;
      value = value.apply(this, Array.prototype.slice.call(arguments, idx, endIdx));
      currentDepth += 1;
      idx = endIdx;
    }
    return value;
  });
});

/**
 * Builds a list from a seed value. Accepts an iterator function, which returns
 * either false to stop iteration or an array of length 2 containing the value
 * to add to the resulting list and the seed to be used in the next call to the
 * iterator function.
 *
 * The iterator function receives one argument: *(seed)*.
 *
 * @func
 * @memberOf R
 * @since v0.10.0
 * @category List
 * @sig (a -> [b]) -> * -> [b]
 * @param {Function} fn The iterator function. receives one argument, `seed`, and returns
 *        either false to quit iteration or an array of length two to proceed. The element
 *        at index 0 of this array will be added to the resulting array, and the element
 *        at index 1 will be passed to the next call to `fn`.
 * @param {*} seed The seed value.
 * @return {Array} The final list.
 * @example
 *
 *      const f = n => n > 50 ? false : [-n, n + 10];
 *      R.unfold(f, 10); //=> [-10, -20, -30, -40, -50]
 * @symb R.unfold(f, x) = [f(x)[0], f(f(x)[1])[0], f(f(f(x)[1])[1])[0], ...]
 */
var unfold = _curry2(function unfold(fn, seed) {
  var pair = fn(seed);
  var result = [];
  while (pair && pair.length) {
    result[result.length] = pair[0];
    pair = fn(pair[1]);
  }
  return result;
});

/**
 * Combines two lists into a set (i.e. no duplicates) composed of the elements
 * of each list.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig [*] -> [*] -> [*]
 * @param {Array} as The first list.
 * @param {Array} bs The second list.
 * @return {Array} The first and second lists concatenated, with
 *         duplicates removed.
 * @example
 *
 *      R.union([1, 2, 3], [2, 3, 4]); //=> [1, 2, 3, 4]
 */
var union = _curry2(compose(uniq, _concat));

/**
 * Returns a new list containing only one copy of each element in the original
 * list, based upon the value returned by applying the supplied predicate to
 * two list elements. Prefers the first item if two items compare equal based
 * on the predicate.
 *
 * @func
 * @memberOf R
 * @since v0.2.0
 * @category List
 * @sig ((a, a) -> Boolean) -> [a] -> [a]
 * @param {Function} pred A predicate used to test whether two items are equal.
 * @param {Array} list The array to consider.
 * @return {Array} The list of unique items.
 * @example
 *
 *      const strEq = R.eqBy(String);
 *      R.uniqWith(strEq)([1, '1', 2, 1]); //=> [1, 2]
 *      R.uniqWith(strEq)([{}, {}]);       //=> [{}]
 *      R.uniqWith(strEq)([1, '1', 1]);    //=> [1]
 *      R.uniqWith(strEq)(['1', 1, 1]);    //=> ['1']
 */
var uniqWith = _curry2(function uniqWith(pred, list) {
  var idx = 0;
  var len = list.length;
  var result = [];
  var item;
  while (idx < len) {
    item = list[idx];
    if (!_includesWith(pred, item, result)) {
      result[result.length] = item;
    }
    idx += 1;
  }
  return result;
});

/**
 * Combines two lists into a set (i.e. no duplicates) composed of the elements
 * of each list. Duplication is determined according to the value returned by
 * applying the supplied predicate to two list elements.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig ((a, a) -> Boolean) -> [*] -> [*] -> [*]
 * @param {Function} pred A predicate used to test whether two items are equal.
 * @param {Array} list1 The first list.
 * @param {Array} list2 The second list.
 * @return {Array} The first and second lists concatenated, with
 *         duplicates removed.
 * @see R.union
 * @example
 *
 *      const l1 = [{a: 1}, {a: 2}];
 *      const l2 = [{a: 1}, {a: 4}];
 *      R.unionWith(R.eqBy(R.prop('a')), l1, l2); //=> [{a: 1}, {a: 2}, {a: 4}]
 */
var unionWith = _curry3(function unionWith(pred, list1, list2) {
  return uniqWith(pred, _concat(list1, list2));
});

/**
 * Tests the final argument by passing it to the given predicate function. If
 * the predicate is not satisfied, the function will return the result of
 * calling the `whenFalseFn` function with the same argument. If the predicate
 * is satisfied, the argument is returned as is.
 *
 * @func
 * @memberOf R
 * @since v0.18.0
 * @category Logic
 * @sig (a -> Boolean) -> (a -> a) -> a -> a
 * @param {Function} pred        A predicate function
 * @param {Function} whenFalseFn A function to invoke when the `pred` evaluates
 *                               to a falsy value.
 * @param {*}        x           An object to test with the `pred` function and
 *                               pass to `whenFalseFn` if necessary.
 * @return {*} Either `x` or the result of applying `x` to `whenFalseFn`.
 * @see R.ifElse, R.when, R.cond
 * @example
 *
 *      let safeInc = R.unless(R.isNil, R.inc);
 *      safeInc(null); //=> null
 *      safeInc(1); //=> 2
 */
var unless = _curry3(function unless(pred, whenFalseFn, x) {
  return pred(x) ? x : whenFalseFn(x);
});

/**
 * Shorthand for `R.chain(R.identity)`, which removes one level of nesting from
 * any [Chain](https://github.com/fantasyland/fantasy-land#chain).
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category List
 * @sig Chain c => c (c a) -> c a
 * @param {*} list
 * @return {*}
 * @see R.flatten, R.chain
 * @example
 *
 *      R.unnest([1, [2], [[3]]]); //=> [1, 2, [3]]
 *      R.unnest([[1, 2], [3, 4], [5, 6]]); //=> [1, 2, 3, 4, 5, 6]
 */
var unnest = chain(_identity);

/**
 * Takes a predicate, a transformation function, and an initial value,
 * and returns a value of the same type as the initial value.
 * It does so by applying the transformation until the predicate is satisfied,
 * at which point it returns the satisfactory value.
 *
 * @func
 * @memberOf R
 * @since v0.20.0
 * @category Logic
 * @sig (a -> Boolean) -> (a -> a) -> a -> a
 * @param {Function} pred A predicate function
 * @param {Function} fn The iterator function
 * @param {*} init Initial value
 * @return {*} Final value that satisfies predicate
 * @example
 *
 *      R.until(R.gt(R.__, 100), R.multiply(2))(1) // => 128
 */
var until = _curry3(function until(pred, fn, init) {
  var val = init;
  while (!pred(val)) {
    val = fn(val);
  }
  return val;
});

/**
 * Returns a list of all the properties, including prototype properties, of the
 * supplied object.
 * Note that the order of the output array is not guaranteed to be consistent
 * across different JS platforms.
 *
 * @func
 * @memberOf R
 * @since v0.2.0
 * @category Object
 * @sig {k: v} -> [v]
 * @param {Object} obj The object to extract values from
 * @return {Array} An array of the values of the object's own and prototype properties.
 * @see R.values, R.keysIn
 * @example
 *
 *      const F = function() { this.x = 'X'; };
 *      F.prototype.y = 'Y';
 *      const f = new F();
 *      R.valuesIn(f); //=> ['X', 'Y']
 */
var valuesIn = _curry1(function valuesIn(obj) {
  var prop;
  var vs = [];
  for (prop in obj) {
    vs[vs.length] = obj[prop];
  }
  return vs;
});

// `Const` is a functor that effectively ignores the function given to `map`.
var Const = function(x) {
  return {value: x, 'fantasy-land/map': function() { return this; }};
};

/**
 * Returns a "view" of the given data structure, determined by the given lens.
 * The lens's focus determines which portion of the data structure is visible.
 *
 * @func
 * @memberOf R
 * @since v0.16.0
 * @category Object
 * @typedefn Lens s a = Functor f => (a -> f a) -> s -> f s
 * @sig Lens s a -> s -> a
 * @param {Lens} lens
 * @param {*} x
 * @return {*}
 * @see R.prop, R.lensIndex, R.lensProp
 * @example
 *
 *      const xLens = R.lensProp('x');
 *
 *      R.view(xLens, {x: 1, y: 2});  //=> 1
 *      R.view(xLens, {x: 4, y: 2});  //=> 4
 */
var view = _curry2(function view(lens, x) {
  // Using `Const` effectively ignores the setter function of the `lens`,
  // leaving the value returned by the getter function unmodified.
  return lens(Const)(x).value;
});

/**
 * Tests the final argument by passing it to the given predicate function. If
 * the predicate is satisfied, the function will return the result of calling
 * the `whenTrueFn` function with the same argument. If the predicate is not
 * satisfied, the argument is returned as is.
 *
 * @func
 * @memberOf R
 * @since v0.18.0
 * @category Logic
 * @sig (a -> Boolean) -> (a -> a) -> a -> a
 * @param {Function} pred       A predicate function
 * @param {Function} whenTrueFn A function to invoke when the `condition`
 *                              evaluates to a truthy value.
 * @param {*}        x          An object to test with the `pred` function and
 *                              pass to `whenTrueFn` if necessary.
 * @return {*} Either `x` or the result of applying `x` to `whenTrueFn`.
 * @see R.ifElse, R.unless, R.cond
 * @example
 *
 *      // truncate :: String -> String
 *      const truncate = R.when(
 *        R.propSatisfies(R.gt(R.__, 10), 'length'),
 *        R.pipe(R.take(10), R.append('…'), R.join(''))
 *      );
 *      truncate('12345');         //=> '12345'
 *      truncate('0123456789ABC'); //=> '0123456789…'
 */
var when = _curry3(function when(pred, whenTrueFn, x) {
  return pred(x) ? whenTrueFn(x) : x;
});

/**
 * Takes a spec object and a test object; returns true if the test satisfies
 * the spec. Each of the spec's own properties must be a predicate function.
 * Each predicate is applied to the value of the corresponding property of the
 * test object. `where` returns true if all the predicates return true, false
 * otherwise.
 *
 * `where` is well suited to declaratively expressing constraints for other
 * functions such as [`filter`](#filter) and [`find`](#find).
 *
 * @func
 * @memberOf R
 * @since v0.1.1
 * @category Object
 * @sig {String: (* -> Boolean)} -> {String: *} -> Boolean
 * @param {Object} spec
 * @param {Object} testObj
 * @return {Boolean}
 * @see R.propSatisfies, R.whereEq
 * @example
 *
 *      // pred :: Object -> Boolean
 *      const pred = R.where({
 *        a: R.equals('foo'),
 *        b: R.complement(R.equals('bar')),
 *        x: R.gt(R.__, 10),
 *        y: R.lt(R.__, 20)
 *      });
 *
 *      pred({a: 'foo', b: 'xxx', x: 11, y: 19}); //=> true
 *      pred({a: 'xxx', b: 'xxx', x: 11, y: 19}); //=> false
 *      pred({a: 'foo', b: 'bar', x: 11, y: 19}); //=> false
 *      pred({a: 'foo', b: 'xxx', x: 10, y: 19}); //=> false
 *      pred({a: 'foo', b: 'xxx', x: 11, y: 20}); //=> false
 */
var where = _curry2(function where(spec, testObj) {
  for (var prop in spec) {
    if (_has(prop, spec) && !spec[prop](testObj[prop])) {
      return false;
    }
  }
  return true;
});

/**
 * Takes a spec object and a test object; returns true if the test satisfies
 * the spec, false otherwise. An object satisfies the spec if, for each of the
 * spec's own properties, accessing that property of the object gives the same
 * value (in [`R.equals`](#equals) terms) as accessing that property of the
 * spec.
 *
 * `whereEq` is a specialization of [`where`](#where).
 *
 * @func
 * @memberOf R
 * @since v0.14.0
 * @category Object
 * @sig {String: *} -> {String: *} -> Boolean
 * @param {Object} spec
 * @param {Object} testObj
 * @return {Boolean}
 * @see R.propEq, R.where
 * @example
 *
 *      // pred :: Object -> Boolean
 *      const pred = R.whereEq({a: 1, b: 2});
 *
 *      pred({a: 1});              //=> false
 *      pred({a: 1, b: 2});        //=> true
 *      pred({a: 1, b: 2, c: 3});  //=> true
 *      pred({a: 1, b: 1});        //=> false
 */
var whereEq = _curry2(function whereEq(spec, testObj) {
  return where(map(equals, spec), testObj);
});

/**
 * Returns a new list without values in the first argument.
 * [`R.equals`](#equals) is used to determine equality.
 *
 * Acts as a transducer if a transformer is given in list position.
 *
 * @func
 * @memberOf R
 * @since v0.19.0
 * @category List
 * @sig [a] -> [a] -> [a]
 * @param {Array} list1 The values to be removed from `list2`.
 * @param {Array} list2 The array to remove values from.
 * @return {Array} The new array without values in `list1`.
 * @see R.transduce, R.difference, R.remove
 * @example
 *
 *      R.without([1, 2], [1, 2, 1, 3, 4]); //=> [3, 4]
 */
var without = _curry2(function(xs, list) {
  return reject(flip(_includes)(xs), list);
});

/**
 * Creates a new list out of the two supplied by creating each possible pair
 * from the lists.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig [a] -> [b] -> [[a,b]]
 * @param {Array} as The first list.
 * @param {Array} bs The second list.
 * @return {Array} The list made by combining each possible pair from
 *         `as` and `bs` into pairs (`[a, b]`).
 * @example
 *
 *      R.xprod([1, 2], ['a', 'b']); //=> [[1, 'a'], [1, 'b'], [2, 'a'], [2, 'b']]
 * @symb R.xprod([a, b], [c, d]) = [[a, c], [a, d], [b, c], [b, d]]
 */
var xprod = _curry2(function xprod(a, b) { // = xprodWith(prepend); (takes about 3 times as long...)
  var idx = 0;
  var ilen = a.length;
  var j;
  var jlen = b.length;
  var result = [];
  while (idx < ilen) {
    j = 0;
    while (j < jlen) {
      result[result.length] = [a[idx], b[j]];
      j += 1;
    }
    idx += 1;
  }
  return result;
});

/**
 * Creates a new list out of the two supplied by pairing up equally-positioned
 * items from both lists. The returned list is truncated to the length of the
 * shorter of the two input lists.
 * Note: `zip` is equivalent to `zipWith(function(a, b) { return [a, b] })`.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig [a] -> [b] -> [[a,b]]
 * @param {Array} list1 The first array to consider.
 * @param {Array} list2 The second array to consider.
 * @return {Array} The list made by pairing up same-indexed elements of `list1` and `list2`.
 * @example
 *
 *      R.zip([1, 2, 3], ['a', 'b', 'c']); //=> [[1, 'a'], [2, 'b'], [3, 'c']]
 * @symb R.zip([a, b, c], [d, e, f]) = [[a, d], [b, e], [c, f]]
 */
var zip = _curry2(function zip(a, b) {
  var rv = [];
  var idx = 0;
  var len = Math.min(a.length, b.length);
  while (idx < len) {
    rv[idx] = [a[idx], b[idx]];
    idx += 1;
  }
  return rv;
});

/**
 * Creates a new object out of a list of keys and a list of values.
 * Key/value pairing is truncated to the length of the shorter of the two lists.
 * Note: `zipObj` is equivalent to `pipe(zip, fromPairs)`.
 *
 * @func
 * @memberOf R
 * @since v0.3.0
 * @category List
 * @sig [String] -> [*] -> {String: *}
 * @param {Array} keys The array that will be properties on the output object.
 * @param {Array} values The list of values on the output object.
 * @return {Object} The object made by pairing up same-indexed elements of `keys` and `values`.
 * @example
 *
 *      R.zipObj(['a', 'b', 'c'], [1, 2, 3]); //=> {a: 1, b: 2, c: 3}
 */
var zipObj = _curry2(function zipObj(keys, values) {
  var idx = 0;
  var len = Math.min(keys.length, values.length);
  var out = {};
  while (idx < len) {
    out[keys[idx]] = values[idx];
    idx += 1;
  }
  return out;
});

/**
 * Creates a new list out of the two supplied by applying the function to each
 * equally-positioned pair in the lists. The returned list is truncated to the
 * length of the shorter of the two input lists.
 *
 * @function
 * @memberOf R
 * @since v0.1.0
 * @category List
 * @sig ((a, b) -> c) -> [a] -> [b] -> [c]
 * @param {Function} fn The function used to combine the two elements into one value.
 * @param {Array} list1 The first array to consider.
 * @param {Array} list2 The second array to consider.
 * @return {Array} The list made by combining same-indexed elements of `list1` and `list2`
 *         using `fn`.
 * @example
 *
 *      const f = (x, y) => {
 *        // ...
 *      };
 *      R.zipWith(f, [1, 2, 3], ['a', 'b', 'c']);
 *      //=> [f(1, 'a'), f(2, 'b'), f(3, 'c')]
 * @symb R.zipWith(fn, [a, b, c], [d, e, f]) = [fn(a, d), fn(b, e), fn(c, f)]
 */
var zipWith = _curry3(function zipWith(fn, a, b) {
  var rv = [];
  var idx = 0;
  var len = Math.min(a.length, b.length);
  while (idx < len) {
    rv[idx] = fn(a[idx], b[idx]);
    idx += 1;
  }
  return rv;
});

/**
 * Creates a thunk out of a function. A thunk delays a calculation until
 * its result is needed, providing lazy evaluation of arguments.
 *
 * @func
 * @memberOf R
 * @category Function
 * @sig ((a, b, ..., j) -> k) -> (a, b, ..., j) -> (() -> k)
 * @param {Function} fn A function to wrap in a thunk
 * @return {Function} Expects arguments for `fn` and returns a new function
 *  that, when called, applies those arguments to `fn`.
 * @see R.partial, R.partialRight
 * @example
 *
 *      R.thunkify(R.identity)(42)(); //=> 42
 *      R.thunkify((a, b) => a + b)(25, 17)(); //=> 42
 */
var thunkify = _curry1(function thunkify(fn) {
  return curryN(fn.length, function createThunk() {
    const fnArgs = arguments;
    return function invokeThunk() {
      return fn.apply(this, fnArgs);
    };
  });
});

exports.F = F;
exports.T = T;
exports.__ = __;
exports.add = add;
exports.addIndex = addIndex;
exports.adjust = adjust;
exports.all = all;
exports.allPass = allPass;
exports.always = always;
exports.and = and;
exports.any = any;
exports.anyPass = anyPass;
exports.ap = ap;
exports.aperture = aperture;
exports.append = append;
exports.apply = apply;
exports.applySpec = applySpec;
exports.applyTo = applyTo;
exports.ascend = ascend;
exports.assoc = assoc;
exports.assocPath = assocPath;
exports.binary = binary;
exports.bind = bind;
exports.both = both;
exports.call = call;
exports.chain = chain;
exports.clamp = clamp;
exports.clone = clone;
exports.comparator = comparator;
exports.complement = complement;
exports.compose = compose;
exports.composeK = composeK;
exports.composeP = composeP;
exports.composeWith = composeWith;
exports.concat = concat;
exports.cond = cond;
exports.construct = construct;
exports.constructN = constructN;
exports.contains = contains$1;
exports.converge = converge;
exports.countBy = countBy;
exports.curry = curry;
exports.curryN = curryN;
exports.dec = dec;
exports.defaultTo = defaultTo;
exports.descend = descend;
exports.difference = difference;
exports.differenceWith = differenceWith;
exports.dissoc = dissoc;
exports.dissocPath = dissocPath;
exports.divide = divide;
exports.drop = drop;
exports.dropLast = dropLast;
exports.dropLastWhile = dropLastWhile;
exports.dropRepeats = dropRepeats;
exports.dropRepeatsWith = dropRepeatsWith;
exports.dropWhile = dropWhile;
exports.either = either;
exports.empty = empty;
exports.endsWith = endsWith;
exports.eqBy = eqBy;
exports.eqProps = eqProps;
exports.equals = equals;
exports.evolve = evolve;
exports.filter = filter;
exports.find = find;
exports.findIndex = findIndex;
exports.findLast = findLast;
exports.findLastIndex = findLastIndex;
exports.flatten = flatten;
exports.flip = flip;
exports.forEach = forEach;
exports.forEachObjIndexed = forEachObjIndexed;
exports.fromPairs = fromPairs;
exports.groupBy = groupBy;
exports.groupWith = groupWith;
exports.gt = gt;
exports.gte = gte;
exports.has = has;
exports.hasIn = hasIn;
exports.hasPath = hasPath;
exports.head = head;
exports.identical = identical;
exports.identity = identity;
exports.ifElse = ifElse;
exports.inc = inc;
exports.includes = includes;
exports.indexBy = indexBy;
exports.indexOf = indexOf;
exports.init = init;
exports.innerJoin = innerJoin;
exports.insert = insert;
exports.insertAll = insertAll;
exports.intersection = intersection;
exports.intersperse = intersperse;
exports.into = into;
exports.invert = invert;
exports.invertObj = invertObj;
exports.invoker = invoker;
exports.is = is;
exports.isEmpty = isEmpty;
exports.isNil = isNil;
exports.join = join;
exports.juxt = juxt;
exports.keys = keys;
exports.keysIn = keysIn;
exports.last = last;
exports.lastIndexOf = lastIndexOf;
exports.length = length;
exports.lens = lens;
exports.lensIndex = lensIndex;
exports.lensPath = lensPath;
exports.lensProp = lensProp;
exports.lift = lift;
exports.liftN = liftN;
exports.lt = lt;
exports.lte = lte;
exports.map = map;
exports.mapAccum = mapAccum;
exports.mapAccumRight = mapAccumRight;
exports.mapObjIndexed = mapObjIndexed;
exports.match = match;
exports.mathMod = mathMod;
exports.max = max;
exports.maxBy = maxBy;
exports.mean = mean;
exports.median = median;
exports.memoizeWith = memoizeWith;
exports.merge = merge;
exports.mergeAll = mergeAll;
exports.mergeDeepLeft = mergeDeepLeft;
exports.mergeDeepRight = mergeDeepRight;
exports.mergeDeepWith = mergeDeepWith;
exports.mergeDeepWithKey = mergeDeepWithKey;
exports.mergeLeft = mergeLeft;
exports.mergeRight = mergeRight;
exports.mergeWith = mergeWith;
exports.mergeWithKey = mergeWithKey;
exports.min = min;
exports.minBy = minBy;
exports.modulo = modulo;
exports.multiply = multiply;
exports.nAry = nAry;
exports.negate = negate;
exports.none = none;
exports.not = not;
exports.nth = nth;
exports.nthArg = nthArg;
exports.o = o;
exports.objOf = objOf;
exports.of = of;
exports.omit = omit;
exports.once = once;
exports.or = or;
exports.otherwise = otherwise;
exports.over = over;
exports.pair = pair;
exports.partial = partial;
exports.partialRight = partialRight;
exports.partition = partition;
exports.path = path;
exports.pathEq = pathEq;
exports.pathOr = pathOr;
exports.pathSatisfies = pathSatisfies;
exports.pick = pick;
exports.pickAll = pickAll;
exports.pickBy = pickBy;
exports.pipe = pipe;
exports.pipeK = pipeK;
exports.pipeP = pipeP;
exports.pipeWith = pipeWith;
exports.pluck = pluck;
exports.prepend = prepend;
exports.product = product;
exports.project = project;
exports.prop = prop;
exports.propEq = propEq;
exports.propIs = propIs;
exports.propOr = propOr;
exports.propSatisfies = propSatisfies;
exports.props = props;
exports.range = range;
exports.reduce = reduce;
exports.reduceBy = reduceBy;
exports.reduceRight = reduceRight;
exports.reduceWhile = reduceWhile;
exports.reduced = reduced;
exports.reject = reject;
exports.remove = remove;
exports.repeat = repeat;
exports.replace = replace;
exports.reverse = reverse;
exports.scan = scan;
exports.sequence = sequence;
exports.set = set;
exports.slice = slice;
exports.sort = sort;
exports.sortBy = sortBy;
exports.sortWith = sortWith;
exports.split = split;
exports.splitAt = splitAt;
exports.splitEvery = splitEvery;
exports.splitWhen = splitWhen;
exports.startsWith = startsWith;
exports.subtract = subtract;
exports.sum = sum;
exports.symmetricDifference = symmetricDifference;
exports.symmetricDifferenceWith = symmetricDifferenceWith;
exports.tail = tail;
exports.take = take;
exports.takeLast = takeLast;
exports.takeLastWhile = takeLastWhile;
exports.takeWhile = takeWhile;
exports.tap = tap;
exports.test = test;
exports.then = then;
exports.times = times;
exports.toLower = toLower;
exports.toPairs = toPairs;
exports.toPairsIn = toPairsIn;
exports.toString = toString$1;
exports.toUpper = toUpper;
exports.transduce = transduce;
exports.transpose = transpose;
exports.traverse = traverse;
exports.trim = trim;
exports.tryCatch = tryCatch;
exports.type = type;
exports.unapply = unapply;
exports.unary = unary;
exports.uncurryN = uncurryN;
exports.unfold = unfold;
exports.union = union;
exports.unionWith = unionWith;
exports.uniq = uniq;
exports.uniqBy = uniqBy;
exports.uniqWith = uniqWith;
exports.unless = unless;
exports.unnest = unnest;
exports.until = until;
exports.update = update;
exports.useWith = useWith;
exports.values = values;
exports.valuesIn = valuesIn;
exports.view = view;
exports.when = when;
exports.where = where;
exports.whereEq = whereEq;
exports.without = without;
exports.xprod = xprod;
exports.zip = zip;
exports.zipObj = zipObj;
exports.zipWith = zipWith;
exports.thunkify = thunkify;

Object.defineProperty(exports, '__esModule', { value: true });

})));