The ES6 draft specifies that `map()`, when applied to a typed array,
yields another instance of that same type. For converting between
array types, the `from()` method is added:

    var f1 = new Float32Array();
    ...
    var f2 = f1.map(x => x * 2); // Yields Float32Array
    var i1 = Int32Array.from(f, x => x * 2); // Yields Int32Array

This is nice. However, there are some small differences between
the two that I think ought to be aligned.

In particular, `map` supplies its closure with three arguments: the
Element (`this[i]`), Index (`i`), and Collection (`this`). The index
is particularly useful, since you can write things like:

    var f3 = f1.map((e, i) => e + i)

It seems that `from` only supplies the E argument though and not the I
and C. I propose this be changed to match `map()`.



Niko

The ES6 draft specifies that `map()`, when applied to a typed array,
yields another instance of that same type. For converting between
array types, the `from()` method is added:

    var f1 = new Float32Array();
    ...
    var f2 = f1.map(x => x * 2); // Yields Float32Array
    var i1 = Int32Array.from(f, x => x * 2); // Yields Int32Array

This is nice. However, there are some small differences between
the two that I think ought to be aligned.

In particular, `map` supplies its closure with three arguments: the
Element (`this[i]`), Index (`i`), and Collection (`this`). The index
is particularly useful, since you can write things like:

    var f3 = f1.map((e, i) => e + i)

It seems that `from` only supplies the E argument though and not the I
and C. I propose this be changed to match `map()`.