#11345: Template Haskell's handling of infix GADT constructors is broken -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: RyanGlScott Type: bug | Status: new Priority: normal | Milestone: Component: Template Haskell | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): Actually, here's a better idea. My above comment shows that trying to encode whether a GADT constructor is declared infix directly into `GadtC` causes problems. But perhaps we don't need to do this. In theory, all we have to do is find out if there is a fixity declaration for the constructor. We're close to being able to do this in Template Haskell already through `reifyFixity`. The problem is that `reifyFixity` will return `defaultFixity` if it can't discover a user-defined fixity declaration for the argument, which leaves the programmer unable to know whether the user actually wrote that fixity, or if it's just `defaultFixity`. With a modest change to `reifyFixity`, {{{#!hs reifyFixity :: Name -> Maybe Fixity }}} where `Nothing` indicates the absence of a user-specified fixity declaration, then I think this would work! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11345#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler