#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:4 adamgundry]:
I'm not really convinced by the original ticket: couldn't you just as well do something like
On the other hand, being able to declare a bunch of specializations such
Yes you can at the expense of introducing extraneous definitions, your solution works fine for the original example but I fear it does not scale. that GHCi or Haddock can display them does seem rather useful, especially for the kind of very polymorphic code you get in `lens` or the post-FTP Prelude. Yes, I also emphasise parentheses to shift students' thinking from: {{{#!hs map :: (a -> b) -> [a] -> [b] }}} to {{{#!hs map :: (a -> b) -> ([a] -> [b]) }}} You would never create a new function to accomplish this minor task but maybe this definition of `fmap` would prove useful to some: {{{#!hs class Functor f where {-# TYPECHECK fmap :: (a -> b) -> (f a -> f b) #-} fmap :: (a -> b) -> f a -> f b }}} Who knows. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11439#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler