#7137: Unnecessary -XRank2Types requirement involving type alias containing "forall" from another module ----------------------------------------+----------------------------------- Reporter: joeyadams | Owner: simonpj Type: bug | Status: closed Priority: highest | Milestone: 7.6.1 Component: Compiler | Version: 7.7 Resolution: wontfix | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: GHC rejects valid program | Difficulty: Unknown Testcase: | Blockedby: Blocking: | Related: ----------------------------------------+----------------------------------- Changes (by simonpj):
* status: new => closed * resolution: => wontfix Comment: Joey is right that `Int -> forall a. a` is technically a rank-1 type. But #5957 complained about a rank-1 type of this sort, in fact more like `Int -> Ord a => a -> a`, that was accepted without any flags. And that does seem wrong. So I did the technically-incorrect thing of requiring `Rank2Types` or `RankNTypes` if you want a forall after an arrow. It just doesn't seem worth the flaggery to allow only rank-1 types, but with foralls after arrows. I propose not to fix this unless it's very painful for some reason. Re- open if so. I will improve the documentation though. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7137#comment:4> 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