tcfail001.hs:9:warning:
    Duplicate class assertion `[(`A',
				    `a'),
				(`A',
				    `a')]' in context:
	[(`A',
	     `a'),
	 (`A',
	     `a')]
 
tcfail001.hs:9: Couldn't match the type
		    `PrelBase.[]' against `GHC.-> [t{-anj-}]'
    Expected: `[a{-ani-}]'
    Inferred: `[t{-anj-}] -> [t{-ank-}]'
    In an equation for function `op':
	`op PrelBase.[]
		    =   PrelBase.[]'


Compilation had errors