[GHC] #7642: Nullary type classes

[GHC]

#7642: Nullary type classes
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    Reporter:  shachaf                  |       Owner:                  
        Type:  feature request          |      Status:  new             
    Priority:  normal                   |   Milestone:                  
   Component:  Compiler (Type checker)  |     Version:  7.6.1           
    Keywords:                           |          Os:  Unknown/Multiple
Architecture:  Unknown/Multiple         |     Failure:  None/Unknown    
  Difficulty:  Unknown                  |    Testcase:                  
   Blockedby:                           |    Blocking:                  
     Related:                           |  
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Changes (by simonpj):

  * difficulty:  => Unknown


Comment:

 Can you say ''why'' you strongly support it?  It looks very marginal to
 me.  The only reason it vaguely makes sense is that it's easy to
 implement.  But if you have
 {{{
 isPrime :: RiemannHypothesis => Integer -> Bool
 isPrime = ... blah...
 }}}
 then the chances are that this will also compile
 {{{
 isPrime :: Integer -> Bool
 isPrime = ... blah...
 }}}
 because presumably the instance exists.  To me it seems marginal, and at
 worst confusing.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7642#comment:2>
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