[GHC] #4282: Data.List.intersperse not lazy enough

[GHC]

#4282: Data.List.intersperse not lazy enough
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    Reporter:  daniel.is.fischer  |       Owner:                       
        Type:  proposal           |      Status:  new                  
    Priority:  normal             |   Component:  libraries/base       
     Version:  6.12.3             |    Keywords:  intersperse, laziness
    Testcase:                     |   Blockedby:                       
          Os:  Unknown/Multiple   |    Blocking:                       
Architecture:  Unknown/Multiple   |     Failure:  Other                
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Comment(by maeder):

 Does the following implementation gain something?
 {{{
 intersperse :: a -> [a] -> [a]
 intersperse s l = case l of
   [] -> l
   x : r -> x : case r of
     [] -> r
     _ -> s : intersperse s r
 }}}

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4282#comment:2>
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