#12700: Don't warn about redundant constraints for type equalities -------------------------------------+------------------------------------- Reporter: crockeea | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by crockeea): I'm not sure why the extra syntax is needed, i.e. how is `let b ~ Foo a` different from `b ~ Foo a`? I'm intending, as hsyl20 indicated, to do the former, but apparently using the `b ~ Foo a` implies, and is more general than, `let b ~ Foo a`. Is there no way for GHC to turn the signature `forall a b . (b ~ Foo a) => a -> b` into `forall a . (let b ~ Foo a) => a -> b` or even `forall a . a -> Foo a`? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12700#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler