#6018: Injective type families -------------------------------+------------------------------------------- Reporter: lunaris | Owner: simonpj Type: feature | Status: new request | Milestone: 7.10.1 Priority: normal | Version: 7.4.1 Component: Compiler | Keywords: TypeFamilies, Injective Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: #4259 None/Unknown | Test Case: | Blocking: | -------------------------------+------------------------------------------- Comment (by goldfire): I thinking about this ticket, I've imagined some syntax like this: {{{ type family FullyInjective a | Result -> a -- use a fun-dep-like syntax, where "Result" is a keyword, capitalized to avoid name-clashes with type variables type family Plus a b | Result a -> b, Result b -> a type family Only1stInjective a b | Result -> a }}} I could even imagine having dependencies among the arguments, though that might be a little strange. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/6018#comment:34 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler