#11967: Custom message when showing functions, comparing functions, ... -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- One of the [https://ghc.haskell.org/trac/ghc/wiki/Proposal/CustomTypeErrors#Examples examples] of type errors: {{{#!hs instance TypeError (Text "Cannot 'Show' functions." :$$: Text "Perhaps there is a missing argument?") => Show (a -> b) where showsPrec = error "unreachable" }}} We already have [https://hackage.haskell.org/package/base-4.8.2.0/docs/src/Text.Show.Function... Text.Show.Functions], is there a place in `base` for this along with `Ord (a -> b)` instances and co. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11967 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler