[GHC] #3634: Add traceM, traceShowM and withTrace

[GHC]

#3634: Add traceM, traceShowM and withTrace
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    Reporter:  MartijnVanSteenbergen  |        Owner:                  
        Type:  proposal               |       Status:  new             
    Priority:  normal                 |    Milestone:  Not GHC         
   Component:  libraries/base         |      Version:  6.10.4          
    Severity:  normal                 |   Resolution:                  
    Keywords:                         |   Difficulty:  Unknown         
    Testcase:                         |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple       |  
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Changes (by igloo):

  * difficulty:  => Unknown
  * milestone:  => Not GHC

Comment:

 I'm not sure the discussion has reached a conclusion yet, e.g. in
 http://article.gmane.org/gmane.comp.lang.haskell.libraries/12087
 Simon Marlow asks if `traceShowM` is necessary. It might be better to send
 a current summary message to the list, and see if there are any more
 comments.

 If we do have a `traceShowM` then I would have thought
 {{{
 traceShowM :: (Show a, Monad m) => String -> a -> m ()
 traceShowM msg x = traceM (msg ++ show x)
 }}}
 to be more useful, similar to withTrace.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3634#comment:1>
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