Wildcards in type synonyms

[ÉRDI Gergő]

On Thu, 28 Jul 2022, Simon Peyton Jones wrote:

> You need to be super-careful about the *level* of wildcards.  That is a tricky bit
> about the whole wildcard implementation.

Indeed! Ensuring the fresh metavars are at `topTcLevel` seems to have 
fixed my problem. My goal doesn't include support higher-rank types at all, 
anyway, so this should be good enough for now.

Thanks, this was the key to all my troubles.