#7395: DefaultSignatures conflict with default implementations -------------------------------------+------------------------------------- Reporter: cgaebel | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.1 Resolution: | Keywords: | DefaultSignatures Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: 7346 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Iceland_jack): Replying to [comment:19 aspiwack]:

I found myself, today, in a situation where I wanted to have two default signatures, something like:

You might be interested in [https://gist.github.com/Icelandjack/e1ddefb0d5a79617a81ee98c49fbbdc4 an idea] I'm developing, {{{#!hs newtype WrapInt = WrapInt Int newtype WrapBool = WrapBool Bool instance Foo WrapInt where foo :: WrapInt foo = WrapInt 0 instance Foo WrapBool where foo :: WrapBool foo = WrapBool False }}} and you should be able to derive {{{#!hs newtype I = MkI Int deriving as WrapInt (Foo) newtype B = MkB Bool deriving as WrapBool (Foo) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/7395#comment:20 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler