#10653: PatternSynonyms should be imported/exported as part of the wildcard notation -------------------------------------+------------------------------------- Reporter: gridaphobe | Owner: mpickering Type: feature request | Status: new Priority: high | Milestone: 8.0.1 Component: Compiler | Version: 7.11 Resolution: | Keywords: | PatternSynonyms, pattern synonyms Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1258 -------------------------------------+------------------------------------- Comment (by simonpj): I've added a pointer to the new specification page to the ticket Description. Personally I think we should Keep It Simple. All this talk of satisfiability makes me shiver. I suggest this: allow T( P ) in all situations except where `P`'s type is ''visibly incompatible'' with `T`. What does "visibly incompatible" mean? `P` is visibly incompatible with `T` if * `P`'s type is of form `... -> S t1 t2` * `S` is a data/newtype constructor distinct from `T` Nothing harmful happens if we allow `P` to be exported with a type it can't possibly be useful for, but specifying a tighter relationship is very awkward as you have discovered. BTW, you'd better say that `T( P )` is ''not'' ok if `T` is a type synonym. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10653#comment:36 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler