Casting MapResult

anonymous via Digitalmars-d-learn digitalmars-d-learn at puremagic.com
Mon Jun 15 08:24:26 PDT 2015


On Monday, 15 June 2015 at 15:10:24 UTC, jmh530 wrote:
> float[] exp(float[] x) {
> 	auto y = x.map!(a => exp(a));
> 	cast(float[]) y;
> 	return y;
> }
>
> But I get an error that I can't convert MapResult!(__lambda2, 
> float[]) to float[].
>
> 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).

First off: Don't cast unless you know exactly what you're doing. 
It's easy to stumble into undefined behaviour land with casts.

To answer the question: You can convert from from MapResult to 
float[], but not with a cast. Instead, use std.array.array:
     import std.array: array;
     return x.map!(std.math.exp).array;


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