function groupBy is weired

[HaskellZhangSong]

No description provided.

[harry75369]

groupBy will not function correctly if key is an array. Since getHashCode of the Dictionary implementation in l2o.js will not compare two arrays by values. One possible hack is to convert array into string first, as the following shows

var Ix = require('ix');

var xs = Ix.Enumerable.fromArray([
  ['hangzhou','2003'],
  ['hangzhou','2003'],
  ['shenzhen','2013'],
  ['shenzhen','2013']
]);

var printEnumerable = function(e) {
  e.forEach(function(x){console.log(x);});
};

var t = xs.groupBy(function(x) {
    //return [x[0],x[1]]; // wrong
    /* output:
    { key: [ 'hangzhou', '2003', getHashCode: [Function] ],
      values: [ [ 'hangzhou', '2003' ] ] }
    { key: [ 'hangzhou', '2003', getHashCode: [Function] ],
      values: [ [ 'hangzhou', '2003' ] ] }
    { key: [ 'shenzhen', '2013', getHashCode: [Function] ],
      values: [ [ 'shenzhen', '2013' ] ] }
    { key: [ 'shenzhen', '2013', getHashCode: [Function] ],
      values: [ [ 'shenzhen', '2013' ] ] }
    */

    return ""+[x[0],x[1]]; // correct
    /* output:
    { key: 'hangzhou,2003',
      values: [ [ 'hangzhou', '2003' ], [ 'hangzhou', '2003' ] ] }
    { key: 'shenzhen,2013',
      values: [ [ 'shenzhen', '2013' ], [ 'shenzhen', '2013' ] ] }
    */
}, function(x) {
    return x;
}, function(key, values) {
    var res = {};
    res['key'] = key;
    res['values'] = values.toArray();
    return res;
});

printEnumerable(t)