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Missing MonadFail (Kleisli m a)

instance MonadFail m => MonadFail (Kleisli m a) where
 fail :: String -> Kleisli m a b
 fail message = Kleisli \_ -> fail message

this would allow

  • data GHCi.UI.Monad.GHCi to derive MonadFail via Kleisli Ghc (IORef GHCiSTate)
  • newtype Text.ParserCombinators.ReadPrec.ReadPrec to derive MonadFail via Kleisli ReadP Prec

See #17993.

Edited by Icelandjack
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