#8999: Type synonym not normalized in instance head ------------------------------------+------------------------------------- Reporter: edsko | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Consider {{{ {-# LANGUAGE ConstraintKinds, KindSignatures #-} type Foo (m :: * -> *) = Monad m data T a = T (Maybe a) instance Foo T where return = T Nothing }}} this gives the bogus error {{{ T.hs:8:3: ‘return’ is not a (visible) method of class ‘Foo’ }}} incidentally, it works okay when giving no where clause. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8999 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler