Generics for higher order functions

gistfile1.ts

function map<I,O>(array:I[], mapper:(value:I) => O) : O[] {
	var result:O[] = [];
	var index = 0;
	for(;index < array.length; ++index) {
		result.push(mapper(array[index]));
	}
	return result;
}

function reduce<I,O>(array:I[], reducer:(reduced:O, value:I) => O, initialValue: O) : O {
	var result = initialValue;
	var index = 0;
	for(;index < array.length; ++index) {
		result = reducer(result, array[index]);
	}
	return result;
}

interface Fooable {
	foo:number
}

interface Barable {
	bar:number
}

class FooImpl implements Fooable {
	constructor(public foo:number) {}
}

var values = [1,2,4,5,6];
var mapped = map(values, (x:number) : Fooable => new FooImpl(x));
var squared = map(mapped, x => x.foo * x.foo);
var reduced = reduce(squared, (r, x) => x+","+r, "");
alert(reduced);