#11439: Request for comments: Allow duplicate type signatures -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Iceland_jack): Replying to [comment:1 goldfire]:
On the other hand, this is a good idea for a pragma. Perhaps
{{{ foo :: a -> a foo x = x
{-# TYPECHECK foo :: Bool -> Bool foo :: Int -> Int foo :: Maybe a -> Maybe a foo True :: Bool map id [] #-} }}}
My gut feeling is that it must take local assumptions into account, swapping equations may confuse more than it helps (resulting from shifting equations around): {{{#!hs {-# TYPECHECK sum :: SBool False -> [Natural] -> Natural #-} sum STrue x = x {-# TYPECHECK sum :: SBool True -> Natural -> Natural #-} sum SFalse [] = 0 sum SFalse (x : xs) = x + sum SFalse xs }}} One of my syntax suggestions was an attempt to capture the local assumptions (#11387?): {{{#!hs sum @False :: SBool False -> [Natural] -> Natural sum @False SFalse :: [Natural] -> Natural }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11439#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler