Can we make mixin applications first class at the type level?

[FeepingCreature]

On Thursday, 21 March 2019 at 12:49:44 UTC, sighoya wrote:
> No, they don't. std.meta give you AliasSeq:
>
> template AliasSeq(TList...)
> {
>     alias AliasSeq = TList;
> }
>
> which seems to be a hack.
> Does it work if I want to have a map instead, no!
>

staticMap... do you mean a mapping of types to other types? Use 
specialized templates:

alias foo(T : int) = string;
alias foo(T : string) = float;

> The limitations we have here are owed by the constrained 
> support of type level programming. We can't do all what we can 
> do at runtime at compile time because the static programming is 
> very limited except? we execute a runtime function at compile 
> time but a runtime function can also be executed at runtime and 
> can't handle transformations on types because types don't exist 
> at runtime, but strings exists at runtime, right?
> ...
> If we would have AliasMap which is mutable, then maybe.

It sounds like you're committed to doing imperative logic to 
manipulate types, when there's a rich library of functional 
template-based solutions to type problems. Could D offer ctfe 
native manipulation of types? Sure, and it would be handier in 
many situations, but there's a rich library of functional, 
template-based idioms available for your use that can, in my 
opinion, probably solve any type problem you have, and won't 
require you using strings as a weird metalanguage out of no 
clearly established need.