[GHC] #8763: forM_ [1..N] does not get fused (10 times slower than go function)

[GHC]

#8763: forM_ [1..N] does not get fused (10 times slower than go function)
-------------------------------------+-------------------------------------
        Reporter:  nh2               |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  7.6.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #7206             |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by simonpj):

 I ''really'' don't want to add new annotations!

 Would it be possible to distil out a small example of what goes wrong with
 `integer`?  It may not be fixable, but it's always worth a try.

 I suppose the gain here is important... it's a fairly common case.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8763#comment:57>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler