[GHC] #4359: Implement lambda-case/lambda-if

[GHC]

#4359: Implement lambda-case/lambda-if
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    Reporter:  batterseapower    |        Owner:              
        Type:  feature request   |       Status:  new         
    Priority:  normal            |    Milestone:              
   Component:  Compiler          |      Version:  7.1         
    Keywords:                    |     Testcase:              
   Blockedby:                    |   Difficulty:              
          Os:  Unknown/Multiple  |     Blocking:              
Architecture:  Unknown/Multiple  |      Failure:  None/Unknown
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Comment(by simonmar):

 hmm, on second thoughts I revise that to +0 for lambda-case and lambda-if.
 They save a constant number of tokens (4), but the downside is that we
 have to adjust our mental parsers/typecheckers to recognise `if then` and
 `case of` as a lambda, and I'm not sure the gain in brevity is worth the
 loss of readability.  (note that multi-way if doesn't suffer from this
 problem, it's just an abbreviation).

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4359#comment:4>
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