testsuite/tests/ghc-regress/indexed-types/should_compile/Col2.hs


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{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE FlexibleContexts #-}

module Col  where 

type family Elem c

type instance Elem [e] = e

class (Eq (Elem c)) => Col c where
  count     :: Elem c -> c -> Int

instance Eq e => Col [e] where
  count	    x = length . filter (==x)