Wildcards in type synonyms

[ÉRDI Gergő]

On Fri, 22 Jul 2022, Simon Peyton Jones wrote:

>       So it seems that instead of shoehorning it into the existing type
>       synonyms, a better bet would be to branch off to a separate path quite
>       early (maybe as soon as during renaming), expand them during
>       typechecking, and *not* touch how/when existing "normal" type synonyms
>       are resolved.
> 
> 
> That sounds plausible, yes.

Do we have an existing way of substituting types over type variables, *in 
HsType instead of Core Type*?