#16059: checkValidType is defeated by a type synonym -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.8.1 Component: Compiler (Type | Version: 8.7 checker) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC accepts | Unknown/Multiple invalid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): But there is nothing fundamentally wrong with `Foo`. You might write {{{ f :: Foo Int }}} which means the same as {{{ f :: Eq Int => Int }}} which is a perfectly legal type. `checkValidType` checks for reasons a type might be invalid ''other than'' its kind. Are you sure you want type synonyms to hide all the things we check thereby? TL;DR: I'm suggesting that if it's valid, it should be valid after expanding synonyms. You are suggesting that ''they should offer some level of abstraction''. I'm unconvinced. Exactly what level of abstraction? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16059#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler