#6018: Injective type families -------------------------------------+------------------------------------- Reporter: lunaris | Owner: jstolarek Type: feature | Status: new request | Milestone: 7.10.1 Priority: normal | Version: 7.4.1 Component: Compiler | Keywords: TypeFamilies, Resolution: | Injective Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: #4259 Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by jstolarek): Replying to [comment:59 goldfire]:
plain old injectivity for open type families.
more involved reasoning for closed type families, where inference is possible
I'm not sure what design choices are hidden by these two statements. Do you mean that for open type families we would have: a) simple injectivity in the result only (via annotations) or b) injectivity in some of the arguments (also via annotations); whereas for closed type families we would admit the same kind of injectivity declarations as for open type families and perhaps also injectivity inference as proposed by me in comment 58? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/6018#comment:61 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler