[GHC] #5539: GHC panic - Simplifier ticks exhausted

[GHC]

#5539: GHC panic -  Simplifier ticks exhausted
---------------------------------+------------------------------------------
  Reporter:  hvr                 |          Owner:  simonpj       
      Type:  bug                 |         Status:  new           
  Priority:  high                |      Milestone:  7.4.1         
 Component:  Compiler            |        Version:  7.3           
Resolution:                      |       Keywords:                
        Os:  Linux               |   Architecture:  x86_64 (amd64)
   Failure:  Compile-time crash  |     Difficulty:  Unknown       
  Testcase:                      |      Blockedby:                
  Blocking:                      |        Related:                
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Comment(by rl):

 Right, so ideally we would like to specialise on value arguments as well.
 There is even a ticket for it: #5059. However, specialising on function
 arguments is very tricky because they can change so much during
 optimisation. So it isn't clear if this could be made to work at all.

 To clarify, one problem that leads to code explosion in `vector-
 algorithms` is essentially this:

 {{{
 introsort f x = <large rhs>

 partialSortBy f x = ... introsort f y ... introsort f z ...
 }}}

 When the user calls `partialSortBy f` for a particular function `f`, we
 want to specialise `introsort` for that `f` but we don't want to duplicate
 `introsort`'s rhs. We also want worker/wrapper etc. to happen for the
 specialised `introsort`. How can we do that?

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5539#comment:41>
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