Re: [Haskell-cafe] Repeating type variables in MultiParamTypeClasses instance heads

On Thu, May 06, 2021 at 10:51:32PM +0200, Henning Thielemann wrote:

{-# LANGUAGE MultiParamTypeClasses #-} module FlexibleInstance where

class C a b c where

This class has an empty interface, it just builds triples of types that imply a constraint. No matter how many such triples one creates, there can't be any conflict between them.

instance C [a] [a] [b] where instance C [a] [b] [b] where

These don't conflict. -- Viktor.