#15872: Odd pretty printing of equality constraint in kind ('GHC.Types.Eq# <>) -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.2 Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Poor/confusing | Unknown/Multiple error message | Test Case: Blocked By: | Blocking: Related Tickets: #13933 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): In GHC HEAD (as of commit 2257a86daa72db382eb927df12a718669d5491f8), you get the following error when compiling the original program: {{{ GHCi, version 8.7.20181129: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Main ( ../Bug.hs, interpreted ) ../Bug.hs:10:1: error: • Illegal constraint in a kind: forall (a :: WHICH). (a ~ 'OP) => * -> * -> * • In the data type declaration for ‘Fun’ | 10 | data Fun :: forall (a :: WHICH). a ~ OP => Type -> Type -> Type where | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^... }}} Which would suggest that this issue is now moot. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15872#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler