ramda/dist/ramda.js

A practical functional library for JavaScript programmers.

//  Ramda v0.31.3
//  https://github.com/ramda/ramda
//  (c) 2013-2025 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) :
  (global = global || self, 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 F() {
    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 T() {
    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 _typeof(o) {
    "@babel/helpers - typeof";

    return _typeof = "function" == typeof Symbol && "symbol" == typeof Symbol.iterator ? function (o) {
      return typeof o;
    } : function (o) {
      return o && "function" == typeof Symbol && o.constructor === Symbol && o !== Symbol.prototype ? "symbol" : typeof o;
    }, _typeof(o);
  }

  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;
      var hasPlaceholder = false;
      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;
        } else {
          hasPlaceholder = true;
        }
        combinedIdx += 1;
      }
      return !hasPlaceholder && left <= 0 ? fn.apply(this, combined) : _arity(Math.max(0, 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);
    });
  });

  /**
   * As with `addIndex`, `addIndexRight` 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.
   *
   * Unlike `addIndex`, `addIndexRight` iterates from the right to the left.
   *
   * @func
   * @memberOf R
   * @since v0.29.0
   * @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 revmap = (fn, ary) => R.map(fn, R.reverse(ary));
   *      const revmapIndexed = R.addIndexRight(revmap);
   *      revmapIndexed((val, idx) => idx + '-' + val, ['f', 'o', 'o', 'b', 'a', 'r']);
   *      //=> [ '5-r', '4-a', '3-b', '2-o', '1-o', '0-f' ]
   */
  var addIndexRight = _curry1(function addIndex(fn) {
    return curryN(fn.length, function () {
      var origFn = arguments[0];
      var list = arguments[arguments.length - 1];
      var idx = list.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.
   *
   * When `idx < -list.length || idx >= list.length`, the original list is returned.
   *
   * @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']
   *
   *      // out-of-range returns original list
   *      R.adjust(4, R.toUpper, ['a', 'b', 'c', 'd']);      //=> ['a', 'b', 'c', 'd']
   *      R.adjust(-5, 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) {
    var len = list.length;
    if (idx >= len || idx < -len) {
      return list;
    }
    var _idx = (len + idx) % len;
    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 created by [transducerCreator] 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} transducerCreator transducer factory if object is transformer
   * @param {Function} fn default ramda implementation
   * @return {Function} A function that dispatches on object in list position
   */
  function _dispatchable(methodNames, transducerCreator, fn) {
    return function () {
      if (arguments.length === 0) {
        return fn();
      }
      var obj = arguments[arguments.length - 1];
      if (!_isArray(obj)) {
        var idx = 0;
        while (idx < methodNames.length) {
          if (typeof obj[methodNames[idx]] === 'function') {
            return obj[methodNames[idx]].apply(obj, Array.prototype.slice.call(arguments, 0, -1));
          }
          idx += 1;
        }
        if (_isTransformer(obj)) {
          var transducer = transducerCreator.apply(null, Array.prototype.slice.call(arguments, 0, -1));
          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 init() {
      return this.xf['@@transducer/init']();
    },
    result: function result(_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;
  };
  function _xall(f) {
    return function (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;
  }));

  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];
  }

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

  // 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;

  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 () {

    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, R.toPairs
   * @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;
  });

  /**
   * 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(async () => {}); //=> "AsyncFunction"
   *      R.type(undefined); //=> "Undefined"
   *      R.type(BigInt(123)); //=> "BigInt"
   */
  var type = _curry1(function type(val) {
    return val === null ? 'Null' : val === undefined ? 'Undefined' : Object.prototype.toString.call(val).slice(8, -1);
  });

  /**
   * 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 comparison 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 (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 _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 _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 _arrayReduce(reducer, acc, list) {
    var index = 0;
    var length = list.length;
    while (index < length) {
      acc = reducer(acc, list[index]);
      index += 1;
    }
    return acc;
  }

  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 _filterMap(fn, map) {
    var result = new Map();
    var iterator = map.entries();
    var current = iterator.next();
    while (!current.done) {
      if (fn(current.value[1])) {
        result.set(current.value[0], current.value[1]);
      }
      current = iterator.next();
    }
    return result;
  }

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

  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;
  };
  function _xfilter(f) {
    return function (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, Maps, 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
   * @category Object
   * @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(['fantasy-land/filter', 'filter'], _xfilter, function (pred, filterable) {
    return _isObject(filterable) ? _arrayReduce(function (acc, key) {
      if (pred(filterable[key])) {
        acc[key] = filterable[key];
      }
      return acc;
    }, {}, keys(filterable)) : _isMap(filterable) ? _filterMap(pred, 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 !== 0;
   *
   *      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 mapPairs(obj, keys) {
      return _map(function (k) {
        return _quote(k) + ': ' + recur(obj[k]);
      }, keys.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 Map]':
        return 'new Map(' + recur(Array.from(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 Set]':
        return 'new Set(' + recur(Array.from(x).sort()) + ')';
      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 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) {
    if (a === b) {
      return b;
    }
    function safeMax(x, y) {
      if (x > y !== y > x) {
        return y > x ? y : x;
      }
      return undefined;
    }
    var maxByValue = safeMax(a, b);
    if (maxByValue !== undefined) {
      return maxByValue;
    }
    var maxByType = safeMax(_typeof(a), _typeof(b));
    if (maxByType !== undefined) {
      return maxByType === _typeof(a) ? a : b;
    }
    var stringA = toString$1(a);
    var maxByStringValue = safeMax(stringA, toString$1(b));
    if (maxByStringValue !== undefined) {
      return maxByStringValue === stringA ? a : b;
    }
    return b;
  });

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

  /**
   * 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, R.pluck, R.project
   * @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 _arrayReduce(function (acc, key) {
          acc[key] = fn(functor[key]);
          return acc;
        }, {}, keys(functor));
      default:
        return _map(fn, functor);
    }
  }));

  /**
   * 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;
  };

  function _nth(offset, list) {
    var idx = offset < 0 ? list.length + offset : offset;
    return list[idx];
  }

  function _prop(p, obj) {
    if (obj == null) {
      return;
    }
    return _isInteger(p) ? _nth(p, obj) : obj[p];
  }

  /**
   * 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
   * @typedefn Idx = String | Int | Symbol
   * @sig Idx -> {s: a} -> a | Undefined
   * @param {String|Number} p The property name or array index
   * @param {Object} obj The object to query
   * @return {*} The value at `obj.p`.
   * @see R.path, R.props, R.pluck, R.project, R.nth
   * @example
   *
   *      R.prop('x', {x: 100}); //=> 100
   *      R.prop('x', {}); //=> undefined
   *      R.prop(0, [100]); //=> 100
   *      R.compose(R.inc, R.prop('x'))({ x: 3 }) //=> 4
   */

  var prop = _curry2(_prop);

  /**
   * 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.project, R.prop, 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);
  });

  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
   *      _isArrayLike({nodeType: 1, length: 1}) // => false
   */
  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.length === 0) {
      return true;
    }
    if (x.length > 0) {
      return x.hasOwnProperty(0) && x.hasOwnProperty(x.length - 1);
    }
    return false;
  });

  var symIterator = typeof Symbol !== 'undefined' ? Symbol.iterator : '@@iterator';
  function _createReduce(arrayReduce, methodReduce, iterableReduce) {
    return function _reduce(xf, acc, list) {
      if (_isArrayLike(list)) {
        return arrayReduce(xf, acc, list);
      }
      if (list == null) {
        return acc;
      }
      if (typeof list['fantasy-land/reduce'] === 'function') {
        return methodReduce(xf, acc, list, 'fantasy-land/reduce');
      }
      if (list[symIterator] != null) {
        return iterableReduce(xf, acc, list[symIterator]());
      }
      if (typeof list.next === 'function') {
        return iterableReduce(xf, acc, list);
      }
      if (typeof list.reduce === 'function') {
        return methodReduce(xf, acc, list, 'reduce');
      }
      throw new TypeError('reduce: list must be array or iterable');
    };
  }

  function _xArrayReduce(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);
  }

  /**
   * 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 _xIterableReduce(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 _xMethodReduce(xf, acc, obj, methodName) {
    return xf['@@transducer/result'](obj[methodName](bind(xf['@@transducer/step'], xf), acc));
  }
  var _xReduce = _createReduce(_xArrayReduce, _xMethodReduce, _xIterableReduce);

  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);
  }

  /**
   * 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
   *
   * Be cautious of mutating and returning the accumulator. If you reuse it across
   * invocations, it will continue to accumulate onto the same value. The general
   * recommendation is to always return a new value. If you can't do so for
   * performance reasons, then be sure to reinitialize the accumulator on each
   * invocation.
   *
   * 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
   *      //