[GHC] #2135: Warn if functions are exported whose types cannot be written

[GHC]

#2135: Warn if functions are exported whose types cannot be written
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 Reporter:  dons             |          Owner:         
     Type:  feature request  |         Status:  new    
 Priority:  normal           |      Milestone:         
Component:  Compiler         |        Version:  6.8.2  
 Severity:  normal           |     Resolution:         
 Keywords:  warnings         |     Difficulty:  Unknown
 Testcase:                   |   Architecture:  Unknown
       Os:  Unknown          |  
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Comment (by simonpj):

 An unambiguous (and easier-to-check) specification might be this:

  * Warn if a module `M` exports a function ''with an explicit type
 signature'' that mentions one or more type constructors that are defined
 in `M` but not exported.

 If you want to check for explicit type signatures, there's a flag for
 that. (Albeit no flag to check for explicit type sigs on exports, but
 ignore non-exported functions.  That would be another easy to add flag.)

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2135#comment:2>
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