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As all types in Haskell are inhabited by undefined, any type can be made an instance of a typeclass. True type equality. {-# LANGUAGE GADTs, MultiParamTypeCl
by reuben364 5y ago
As all types in Haskell are inhabited by undefined, any type can be made an instance of a typeclass. True type equality.
{-# LANGUAGE GADTs, MultiParamTypeClasses, FlexibleInstances #-}
data Eq a b = (a ~ b) => Eq
class Revolution a b where
eq :: Eq a b
instance Revolution a b where
eq = undefined