[GHC] #5205: Control.Monad.forever leaks space

[GHC]

#5205: Control.Monad.forever leaks space
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  Reporter:  akio                     |          Owner:  pcapriotti      
      Type:  bug                      |         Status:  merge           
  Priority:  high                     |      Milestone:  7.6.1           
 Component:  libraries/base           |        Version:  7.0.3           
Resolution:                           |       Keywords:                  
        Os:  Unknown/Multiple         |   Architecture:  Unknown/Multiple
   Failure:  Runtime performance bug  |     Difficulty:  Unknown         
  Testcase:  T5205                    |      Blockedby:                  
  Blocking:                           |        Related:                  
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Changes (by pcapriotti):

  * status:  new => merge


Comment:

 Pushed:

 {{{
 commit f55f5574c12ff8dfe57994219eee0702ac8aba2e
 Author: Paolo Capriotti <p.capriotti at gmail.com>
 Date:   Mon Aug 20 16:35:38 2012 +0100

     Improve definition of forever (#5205)

     The previous implementation was:

         forever a = a >> forever a

     which can create a space leak in some cases, even with optimizations.
     The current implementation:

         forever a = let a' = a >> a' in a'

     prevents repeated thunk allocations by creating a single thunk for the
     final result, even without optimizations.
 }}}

 I also removed the note and a `SPECIALISE` pragma in GHC.ST.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5205#comment:14>
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