[Haskell-cafe] "SameConstraints?" type constraints

[Leza Morais Lutonda]

On 06/19/2015 03:02 AM, MigMit wrote:
> Typo.
>
> {-# LANGUAGE ConstraintKinds, GADTs #-}
> data SC c e where SC :: c d => d -> e -> SC c e

Yes, I have activated the GADTs extension too and the data definition itself typechecks but the Show instance do not:

instance Show e => Show (S c e) where
       show (SC x y) = show x ⧺ show y

Because: Could not deduce (Show d) arising from a use of ‘show’

-- 
Leza Morais Lutonda, Lemol-C
http://lemol.github.io



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