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{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies,
UndecidableInstances #-}
-- UndecidableInstances because 'b' appears in the context but not the head
module ShouldCompile where
-- This accepted by Hugs, but not by GHC 4.08.1
-- Reported by Thomas Hallgren Nov 00
class P a
class R a b | b->a
instance (P a,R a b) => P [b]
{- GHC 4.08.1 doesn't seem to allow variables in the context that
don't appear after the =>, but which are still ok since they are
determined by the functional dependenices. -}
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