[GHC] #3315: Add generalised "lookup" function

[GHC]

#3315: Add generalised "lookup" function
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Reporter:  skorpan           |          Owner:                  
    Type:  feature request   |         Status:  new             
Priority:  normal            |      Component:  Prelude         
 Version:  6.11              |       Severity:  minor           
Keywords:                    |       Testcase:                  
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
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 I think it would be very nice to have a default implementation of a
 generalised `lookup` function, such as `lookupWith`.  The code I'm
 currently using is very simple and straight-forward:

 {{{
 lookupWith :: (a -> Bool) -> [(a, b)] -> Maybe b
 lookupWith _ []          = Nothing
 lookupWith p ((x, y):xs) | p x = Just y
                          | otherwise = lookupWith p xs
 }}}

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3315>
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