opCast cannot implicitly convert a.opCast of type X to Y

[Meta]

On Thursday, 15 February 2018 at 00:27:40 UTC, Meta wrote:
> On Wednesday, 14 February 2018 at 23:46:30 UTC, aliak wrote:
>> On Wednesday, 14 February 2018 at 15:14:24 UTC, Meta wrote:
>>
>> Ooh yes, of course! Thank you :)
>
> Even better:
>
> import std.conv;
>
> auto b = a.map!(to!float);

Actually, that won't quite work without redefining map a little:

Optional!U map(alias f, U = typeof(f(t.init)))()
{
     etc...
}