[Haskell-cafe] Pattern synonyms and explicit forall.
anthony.d.clayden at gmail.com
Sat Sep 18 12:12:08 UTC 2021
The end of your error message:
> 63 | pattern Any a <- Some a
> | ^
Appears to have program text (a mono-directional pattern binding) that
doesn't correspond to the program text you quote.
> pattern Any :: forall a. a -> Some
> pattern Any a = Some
Is a implicitly bi-directional pattern binding that will never work. (The
free var `a` on LHS does not appear in RHS.)
I'm suspecting the explicit forall is not much to do with it.
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Haskell-Cafe