#7828: RebindableSyntax and Arrow ----------------------------------------------+---------------------------- Reporter: AlessandroVermeulen | Owner: Type: bug | jstolarek Priority: normal | Status: new Component: Compiler (Type checker) | Milestone: 7.10.1 Resolution: | Version: 7.6.2 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: #1537, | #3613 ----------------------------------------------+---------------------------- Comment (by simonpj): I'm not following all of this, but my instinct is this. The semantics of the program should not depend on the details of desugaring. So the various calls to `arr`, `(>>>)` in the desugarer should not dispatch to different instances depending on the size of the tuple. So the type checker should be able to construct functions `arr-at-T`, `(>>>)-at-T` (for the ambient arrow T) ''that are polymorphic in the environment argument''. The desugarer can then instantiate this polymorphic function at whatever types it needs (maybe several of them). I am having trouble getting to grips with this because I know of no document that gives: * The syntax of the arrow sub-language (including comprehensions) * The typing rules for that language * The desugaring for that language Having such a document would be extremely helpful in making sure we were all on staring from the same baseline. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/7828#comment:34 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler