[GHC] #12790: GHC 8.0.1 uses copious amounts of RAM and time when trying to compile lambdabot-haskell-plugins

[GHC]

#12790: GHC 8.0.1 uses copious amounts of RAM and time when trying to compile
lambdabot-haskell-plugins
-------------------------------------+-------------------------------------
        Reporter:  clint             |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by simonpj):

 That's very helpful.  Alas, `parsec-3.1.11` doesn't compile with HEAD.  I
 get
 {{{
 Text\Parsec\Token.hs:524:27: error:
         Could not deduce (Stream s m t0) arising from a use of    option
       from the context: Stream s m Char
         bound by the type signature for:
                    makeTokenParser :: Stream s m Char =>
                                       GenLanguageDef s u m ->
 GenTokenParser s u m
         at Text\Parsec\Token.hs:(351,1)-(352,63)
       The type variable    t0    is ambiguous
 }}}
 I have not investigated what the problem is.  Does anyone know?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12790#comment:8>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler