Hole-y partial type signatures greatly slow down compile times
This time, I actually mean it. :)
Originally reported here, I distilled the example from this comment into a one file test case.
Sigs.hs is exactly like
NoSigs.hs, except for the fact that it has a bunch of extra type signatures that have a lot of holes. On my machine, this is what compilation times are (I gave up timing after 15 minutes):
|GHC version||8.0.2||8.2.1||8.4.1 (445554b6)|