Casting MapResult

[Justin Whear via Digitalmars-d-learn]

On Mon, 15 Jun 2015 15:10:20 +0000, jmh530 wrote:

> So I suppose I have two questions: 1) am I screwing up the cast, or is
> there no way to convert the MapResult to float[], 2) should I just not
> bother with map (I wrote an alternate, longer, version that doesn't use
> map but returns float[] properly).

MapResult is a wrapper around your original range that performs the 
mapping operation lazily.  If you want eagerly evaluate and get back to 
an array use the std.array.array function:

import std.array : array;
auto y = x.map!(a => exp(a)).array;

Or if you have already allocated an array of the appropriate size you can 
use std.algorithm.copy:

import std.algorithm : copy;
float[] y = new float[](appropriate_length);
x.map!(a => exp(a)).copy(y);