// var _curryN = require('./internal/_curryN')
// var _dispatchable = require('./internal/_dispatchable')
// var _has = require('./internal/_has')
// var _reduce = require('./internal/_reduce')
// var _xreduceBy = require('./internal/_xreduceBy')
//
//
// /**
//  * 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
//  *
//  *      var reduceToNamesBy = R.reduceBy((acc, student) => acc.concat(student.name), []);
//  *      var namesByGrade = reduceToNamesBy(function(student) {
//  *        var score = student.score;
//  *        return score < 65 ? 'F' :
//  *               score < 70 ? 'D' :
//  *               score < 80 ? 'C' :
//  *               score < 90 ? 'B' : 'A';
//  *      });
//  *      var students = [{name: 'Lucy', score: 92},
//  *                      {name: 'Drew', score: 85},
//  *                      // ...
//  *                      {name: 'Bart', score: 62}];
//  *      namesByGrade(students);
//  *      // {
//  *      //   'A': ['Lucy'],
//  *      //   'B': ['Drew']
//  *      //   // ...,
//  *      //   'F': ['Bart']
//  *      // }
//  */
// module.exports = _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)
//   }))