#13846: GHC Panic: Visible type application + function type @(_ -> _) -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.3 Keywords: | Operating System: Unknown/Multiple TypeApplications | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ $ ghci -XTypeApplications -ignore-dot-ghci GHCi, version 8.3.20170605: http://www.haskell.org/ghc/ :? for help Prelude> :t fmap @(_ -> _) ghc: panic! (the 'impossible' happened) (GHC version 8.3.20170605 for x86_64-unknown-linux): repSplitAppTys w0_a1pF[tau:2] w0_a1pH[tau:2] [] Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1133:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1137:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:809:9 in ghc:Type Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Prelude> }}} Doesn't happen with other types it seems, probably something to do with levity polymorphism. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13846 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler