#8767: Add rules involving `coerce` to the libraries -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: task | Status: new Priority: normal | Milestone: 7.10.1 Component: | Version: 7.9 libraries/base | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: 8718 Type of failure: | Related Tickets: #2110 None/Unknown | Test Case: | tests/simplCore/should_run/T2110.hs| Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by dmcclean): Could the compiler always generate `(Functor f, Coercible a b) => Coercible f a -> Coercible f b` instances that magically either `fmap coerce` or `coerce` depending on the role of f's parameter? Wouldn't the concrete type of `f` be known by the time it came around to generating the instance? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8767#comment:19 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler