[GHC] #14996: Typed holes are very slow

[GHC]

#14996: Typed holes are very slow
-------------------------------------+-------------------------------------
           Reporter:  simonpj        |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.2.2
           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:
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 If you type at the GHCi prompt
 {{{
 ghci> 3 _ 4
 }}}
 (which I did for #14969), you get a multi-second pause before the error
 message comes out.

 I think this is because the error-message generator is looking through the
 entire type environment.  But it's really too slow.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14996>
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