#7903: Failure to find class instance specified with extra parentheses -----------------------------+---------------------------------------------- Reporter: conal | Owner: Type: bug | Status: new Priority: normal | Component: Compiler Version: 7.6.3 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: None/Unknown | Blockedby: Blocking: | Related: -----------------------------+---------------------------------------------- The following two-line program fails to compile under GHC 7.6.3 and compiles fine with GHC 7.4.1: {{{ instance Eq (((->) a) b) instance (Ord b) => Ord (((->) a) b) }}} Error message: {{{ Could not deduce (Eq (a -> b)) arising from the superclasses of an instance declaration from the context (Ord b) }}} Compilation goes through if I tweak the {{{Eq}}} instance to use "{{{((->) a b)}}}" or "{{{(a -> b)}}}" in place of "{{{(((->) a) b)}}}". -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7903 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler