#7854: Constrained method type accepted in Haskell 98 mode ---------------------------------+------------------------------------------ Reporter: refold | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: Unknown | Testcase: Blockedby: | Blocking: Related: | ---------------------------------+------------------------------------------ Changes (by simonpj): * difficulty: => Unknown Comment: You are absolutely right. See the H98 report [http://www.haskell.org/onlinereport/decls.html]. In 4.3.1. it says "the cxi may not constrain u", where u is the class variable, and cx is the context of a class method signature. But (a) it's a bit fiddly to fix, (b) it's not clear what exactly it means for multi-parameter type classes, and more seriously it might break some existing programs which are inadvertently straying from H98 definition. So I'm rather inclined to let sleeping dogs lie. Simon -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7854#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler