#8132: Warning for Typeable instances misplaced -------------------------------------------------+------------------------- Reporter: scottgw | Owner: Type: bug | dreixel Priority: normal | Status: new Component: Compiler | Milestone: Resolution: | Version: 7.7 Operating System: Unknown/Multiple | Keywords: Type of failure: Incorrect warning at | Architecture: compile-time | Unknown/Multiple Test Case: | Difficulty: Blocking: | Unknown | Blocked By: | Related Tickets: -------------------------------------------------+------------------------- Comment (by simonpj): It's all coming back; sorry to be so slow. It's true that 95% of all users will see no change because they already say `deriving( Typeable )`. There are very few handwritten instances. It's true that changing the name of the method from `typeOf` to `typeRep` is an unforced change. To me `typeRep` makes more sense; `(typeOf p)` doesn't actually return the type of `p`, which is `Proxy t` for some t. But we could easily include a (deprecated) function {{{ typeOf :: Typeable a => Proxy a -> TypeRep typeOf = typeRep {-# DEPRECATED typeOf "Use typeRep instead" #-} }}} Together that would mean that only a tiny fraction of uses would break; they can if necessary recover the old behaviour via `OldTypeable`; and users would have a release cycle to update to `typeRep`. Sound fair? It's more or less what we have in HEAD now, apart from making manual `Typeable` instances into errors. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8132#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler