Re: [GHC] #10968: Type hole cause bad type checking

14 Oct 2015

      #10968: Type hole cause bad type checking
-------------------------------------+-------------------------------------
        Reporter:  ndtimofeev        |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by mpickering):

 I can't reproduce this. How are you running ghc?

 {{{
 GHCi, version 7.10.2: http://www.haskell.org/ghc/  :? for help
 [1 of 1] Compiling Main             ( test.hs, interpreted )

 test.hs:10:14:
     Found hole ‘_’ with type: ReaderT () m a0
     Where: ‘m’ is a rigid type variable bound by
                the type signature for f1 :: ReaderT () m () -> ReaderT ()
 m ()
                at test.hs:9:7
            ‘a0’ is an ambiguous type variable
     Relevant bindings include
       ev :: ReaderT () m () (bound at test.hs:10:4)
       f1 :: ReaderT () m () -> ReaderT () m () (bound at test.hs:10:1)
     In the second argument of ‘(>>)’, namely ‘_’
     In the first argument of ‘(>>)’, namely ‘f >> _’
     In the expression: f >> _ >> ev
 Failed, modules loaded: none.
 }}}

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10968#comment:1
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler