[GHC] #5807: DPH library functions don't work without -fvectorise. (was: lengthP returns bad result)

[GHC]

#5807: DPH library functions don't work without -fvectorise.
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 Reporter:  benl                         |          Owner:  benl                 
     Type:  bug                          |         Status:  new                  
 Priority:  normal                       |      Component:  Data Parallel Haskell
  Version:  7.2.2                        |       Keywords:                       
       Os:  Unknown/Multiple             |   Architecture:  Unknown/Multiple     
  Failure:  Incorrect result at runtime  |       Testcase:                       
Blockedby:                               |       Blocking:                       
  Related:                               |  
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Comment(by benl):

 DPH programs only work when compiled with -fvectorise. Without
 -fvectorise, the library exports dummy, place-holder functions that don't
 have full implementations. We use place-holders instead of simply throwing
 'error' because these functions need to have the same strictness
 properties as the real ones. This is mentioned at
 http://www.haskell.org/haskellwiki/GHC/Data_Parallel_Haskell

 I'm leaving this bug open to remind us to replace the dummy place-holders
 with real code at some stage. There would be no point running this code
 for performance reasons, but at least it will be less confusing.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5807#comment:1>
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