[GHC] #11313: Awkward error message "Expecting one fewer argument to ‘*’"

28 Dec 2015

      #11313: Awkward error message "Expecting one fewer argument to ‘*’"
-------------------------------------+-------------------------------------
           Reporter:  rwbarton       |             Owner:
               Type:  bug            |            Status:  new
           Priority:  low            |         Milestone:
          Component:  Compiler       |           Version:  7.11
  (Type checker)                     |
           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:
-------------------------------------+-------------------------------------
 The first error below has a strange first line. Admittedly the input is
 nonsense, but as `*` has no arguments, according to the March Hare, it
 can't have one fewer argument.

 Note that the second error does not contain this problematic line.

 {{{
 rwbarton@morphism:/tmp$ ~/ghc-newest/inplace/bin/ghc-stage2 --interactive
 GHCi, version 7.11.20151228: http://www.haskell.org/ghc/  :? for help
 Prelude> import Data.Kind
 Prelude Data.Kind> :set -XTypeApplications
 Prelude Data.Kind> :t fmap @ (*)

 <interactive>:1:8: error:
     • Expecting one fewer argument to ‘*’
       Expected kind ‘* -> *’, but ‘*’ has kind ‘*’
     • In the type ‘*’
       In the expression: fmap @*
 Prelude Data.Kind> :t fmap @ Int

 <interactive>:1:8: error:
     • Expected kind ‘* -> *’, but ‘Int’ has kind ‘*’
     • In the type ‘Int’
       In the expression: fmap @Int
 }}}

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11313
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler