[GHC] #4227: Allow SPECIALISE pragmas for functions defined in another module

[GHC]

#4227: Allow SPECIALISE pragmas for functions defined in another module
---------------------------------+------------------------------------------
    Reporter:  simonpj           |        Owner:              
        Type:  bug               |       Status:  new         
    Priority:  normal            |    Milestone:              
   Component:  Compiler          |      Version:  6.12.3      
    Keywords:                    |   Difficulty:              
          Os:  Unknown/Multiple  |     Testcase:              
Architecture:  Unknown/Multiple  |      Failure:  None/Unknown
---------------------------------+------------------------------------------

Comment(by sebf):

 The motivation for this is [http://github.com/sebfisch/haskell-
 regexp/blob/0.2.0.0/src/Text/RegExp/Matching.hs Matching.hs]. Currently it
 has SPECIALIZE pragmas for Prelude types but more complex matching
 policies like [http://github.com/sebfisch/haskell-
 regexp/blob/0.2.0.0/src/Text/RegExp/Matching/Leftmost.hs Leftmost.hs] must
 use unspecialized matching functions. Ideally, I would just write

 {{{
  {-# SPECIALIZE partialMatch :: RegExp c -> [(Int,c)] -> Leftmost #-}
  {-# SPECIALIZE matchW :: RegW Leftmost c -> [(Int,c)] -> Leftmost #-}
 }}}

 into {{{Leftmost.hs}}} to specialize {{{partialMatch}}} and its overloaded
 dependency {{{matchW}}}.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4227#comment:1>
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