Poor man's Hadoop in Javascript

hadoop.js

var reduce = function(k, list) {
    return [k, list];
};
var map = function(yield, item) {
    yield(item[0], item[1]);
};
var PoorMansHadoop = function(map, reduce, data) {
    var r = data.map(function(node) {
        var mapperOutput = [];
        var yield = function() {
            return function(k, v) {
                mapperOutput.push([k, v]);
            }
        }();
        map(yield, node);
        return mapperOutput;
    }).reduce(function(list, nodeList) {
        nodeList.forEach(function(node) {
            if (list[node[0]]) {
                list[node[0]].push(node[1]);
            } else {
                list[node[0]] = [node[1]];
            }
        });
        return list;
    }, {});

    var output = [];
    for (var key in r) {
        if (r.hasOwnProperty(key)) {
            output.push(reduce(key, r[key]));
        }
    }
    return output;
}

// Example
var result = PoorMansHadoop(function(y, i) {
    y(i, 1);
}, function(k, list) {
    return {
        key:k,
        value:list.reduce(function(a, b){
            return a + b;
        }, 0)
    };
}, ['foo', 'bar', 'apple', 'foo', 'banana', 'foo', 'foo', 'bar']);

Careful there, yield is a reserved keyword.