#11333: GHCi does not discharge satisfied constraints ---------------------------------+---------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Resolution: | Keywords: Operating System: Linux | Architecture: Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | ---------------------------------+---------------------------------------- Comment (by Iceland_jack): This error message can be improved, mention `TypeApplications` as a possible cause alone with monom. {{{#!hs Prelude> :set -XTypeApplications Prelude> data A Prelude> :t (==) @A (==) @A :: Eq A => A -> A -> Bool Prelude> a = (==) @A <interactive>:4:1: error: • No instance for (Eq A) arising from a use of ‘==’ • When instantiating ‘a’, initially inferred to have this overly-general type: Eq A => A -> A -> Bool NB: This instantiation can be caused by the monomorphism restriction. }}} `==@A` here is also not desirable. {{{#!hs % ghci -ignore-dot-ghci GHCi, version 8.1.20160102: http://www.haskell.org/ghc/ :? for help Prelude> data A Prelude> :t (==) @A <interactive>:1:1: error: Pattern syntax in expression context: ==@A Did you mean to enable TypeApplications? }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11333#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler