samples/jsobject_mapreduce.js

#// Usage: jjs -scripting -cp . jsobject_mapreduce.js

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// Many Array.prototype functions such as map,
// filter, reduce, reduceRight, every, some are generic.
// These functions accept ECMAScript array as well as
// many array-like objects including JSObjects.
// See also http://en.wikipedia.org/wiki/MapReduce

`javac BufferArray.java`;

var BufferArray = Java.type("BufferArray");
var buf = new BufferArray(10);

var map = Array.prototype.map;
var filter = Array.prototype.filter;
var reduce = Array.prototype.reduce;

// make random list of numbers
for (var i = 0; i < 10; i++)
    buf[i] = Math.random();

var forEach = Array.prototype.forEach;
// print numbers in the list
forEach.call(buf, function(x) print(x));

// print sum of squares of the random numbers
print("Square sum:",
    reduce.call(
        map.call(buf, function(x) x*x),
        function(x, y) x + y)
);