[GHC] #9404: tcInferRho muddies the waters

[GHC]

#9404: tcInferRho muddies the waters
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              Reporter:  goldfire    |            Owner:  goldfire
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Compiler    |          Version:  7.9
            Resolution:              |         Keywords:
      Operating System:              |     Architecture:  Unknown/Multiple
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by simonpj):

 Re the last question, here's the comment in HEAD
 {{{
        -- Make sure that the argument type has kind '*'
        -- Eg we do not want to allow  (D#  $  4.0#)   Trac #5570
        --    (which gives a seg fault)
        -- We do this by unifying with a MetaTv; but of course
        -- it must allow foralls in the type it unifies with (hence
 PolyTv)!
        --
        -- The result type can have any kind (Trac #8739),
        -- so we can just use res_ty

        -- ($) :: forall (a:*) (b:Open). (a->b) -> a -> b
        ; a_ty <- newPolyFlexibTyVarTy
 }}}
 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9404#comment:6>
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