[Haskell-beginners] Ambogous error in returning value

[Baa]

Hello, David!

Hmm, yes, I got it. Interesting is that I tried to set
explicitly types as `[a]` of `allows opts` and `denies opts` in the
class too (like in instance) but without this extension:

  {-# LANGUAGE ScopedTypeVariables #-}

and Intero nothing helps about "...do you want to include blah-blah,
press C-c C-r..." as usual it does it :)

OK, your explanation is absolutely enought. Thank you!

Have a nice day,


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Best regards, Paul