#4099: Slighlty confusing error message with data families ---------------------------------+------------------------------------------ Reporter: rl | Owner: Type: bug | Status: new Priority: normal | Component: Compiler Version: 6.13 | Keywords: Os: Unknown/Multiple | Testcase: Architecture: Unknown/Multiple | Failure: None/Unknown ---------------------------------+------------------------------------------ Example code:
{{{ data family T a foo :: T a -> a foo (Just x) = x }}} Error message: {{{ Couldn't match expected type `T a' against inferred type `Maybe a1' NB: `T' is a type function In the pattern: Just x In the definition of `foo': foo (Just x) = x }}} Calling `T` a type function is confusing, I had to double check that I hadn't accidentally declared it as a type family. I would * call these things type families and data families in messages and * omit the message for data families altogether because it doesn't matter that `T` is one in this case. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4099> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler _______________________________________________ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs