[GHC] #2042: Add concatMapM to Control.Monad

[GHC]

#2042: Add concatMapM to Control.Monad
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    Reporter:  twanvl    |       Owner:                
        Type:  proposal  |      Status:  new           
    Priority:  normal    |   Component:  libraries/base
     Version:  6.8.2     |    Severity:  normal        
    Keywords:            |    Testcase:                
Architecture:  Unknown   |          Os:  Unknown       
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 I have written this function over and over again for different projects.
 Time to add it to the base libraries:

 {{{
 -- | The 'concatMapM' function generalizes 'concatMap' to arbitrary
 monads.
 concatMapM        :: (Monad m) => (a -> m [b]) -> [a] -> m [b]
 concatMapM f xs   =  liftM concat (mapM f xs)
 }}}

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2042>
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