#8581: Add support for explicitly-bidirectional pattern synonyms -------------------------------------+------------------------------------- Reporter: cactus | Owner: Type: feature | Status: new request | Milestone: 7.10.1 Priority: normal | Version: Component: Compiler | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: 5144 Type of failure: | Related Tickets: None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by cactus): Hmm. Implementation-wise, there's no reason why `P`-as-an-expression and `P`-as-a-pattern has to have the same constraints -- in fact, they could even have completely different types... But we check that they do have the same type so that they behave more like a real constructor. The reason `CE := CP + CR` at the moment is that this is how a GADT constructor is typed. So, ummm, how far do we want to let pattern synonym types wander from regular constructor types? That is the question here. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8581#comment:14 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler