TypeFunction example creatiing a conversion matrix

[Paul Backus]

On Thursday, 1 October 2020 at 21:34:50 UTC, Adam D. Ruppe wrote:
>
> So some facility to turn a ctfe array back into a tuple - the 
> dereifiy step basically - with compiler assistance I think will 
> be practical.

What if we could just mutate tuples locally?

template staticMap(alias F, Args...) {
     static foreach(ref Arg; Args)
         Arg = F!Arg;
     alias staticMap = Args;
}

The obvious objection is "the spec says order of declarations 
doesn't matter", but this is a case where the spec is just 
flat-out wrong (see previous discussion of "compile-time race 
conditions" [1]). So, given that declaration order is in fact 
significant in D, we may as well officially acknowledge it and 
reap the benefits.

[1] 
https://forum.dlang.org/thread/swbmgrhtoiqtqokmqniu@forum.dlang.org?page=2#post-rccfbm:24sjv:241:40digitalmars.com