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Anyone want to guess how many errors this code generates: (kbin.social)

submitted 2 years ago by jaror@kbin.social to c/haskell@kbin.social

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Anyone want to guess how many errors this code generates:

{-# LANGUAGE DerivingVia #-}

module T where

newtype OrdList1 a = OrdList1 [a]
  deriving (Functor, Foldable, Traversable) via []

newtype OrdList2 a = OrdList2 [a]
  deriving (Functor, Foldable, Traversable) via Maybe

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[–] jaror@kbin.social 2 points 2 years ago

For more info see: https://discourse.haskell.org/t/derivingvias-error-messages-are-bad/8217?u=jaror

[–] mangoiv@functional.cafe 0 points 2 years ago (1 children)

@jaror tell me 😳

[–] jaror@kbin.social 1 points 2 years ago* (last edited 2 years ago)

@mangoiv

https://play.haskell.org/saved/m7x3AiIE