[Haskell-cafe] ghc-9 needs type declaration where ghc-8 didn't (with RankNTypes)

Johannes Waldmann johannes.waldmann at htwk-leipzig.de
Thu Oct 1 16:37:54 UTC 2020

> The 9.0 upgrade may help: 
> https://gitlab.haskell.org/ghc/ghc/-/wikis/migration/9.0

Thanks for that pointer!

So, what I observed is an effect of
I was browsing that, but could not make the connection.
"nested foralls" are mentioned only together with
GADT/instance/deriving, none of which is in my example.

- J.

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