I should clarify that this was done on an older kernel (bootstrapped from ghc 6.4 as Jeff Heard suggested), in case that makes any difference:

Main memory size: 7971 Mbytes
1 GenuineIntel Intel(R) Xeon(TM) CPU 3.40GHz processor
Swap Size: 2047 Mbytes
Num Processors: 1
Processor Type:                   Intel(R) Xeon(TM) CPU 3.40GHz x64
Clock Speed: 3400 MHZ
OS: Linux 2.6.9-42.0.3.EL.spi
OS-VERSION: CentOS release 4.4 (Final)
OS-HW: x86_64

Dan Weston wrote:
No, I am using the latest released ghc:

 > ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.10.4

[ z.hs is attached ]

 > time ghc -O0 --make z.hs
[1 of 1] Compiling Main             ( z.hs, z.o )
Linking z ...
14.422u 0.630s 0:15.10 99.6%    0+0k 0+0io 0pf+0w

 > time ./z
z: internal error: scavenge: unimplemented/strange closure type -1 @ 0x2a95a8e000
     (GHC version 6.10.4 for x86_64_unknown_linux)
     Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
Abort
0.007u 0.007s 0:00.02 0.0%      0+0k 0+0io 0pf+0w

Dan

Neil Mitchell wrote:
Hi

I think the issue you're running in to with 6.4 is this one:
http://hackage.haskell.org/trac/ghc/ticket/830 - known and fixed a
while back.

Thanks

Neil

On Thu, Aug 6, 2009 at 9:59 PM, Dan Weston<weston...@imageworks.com> wrote:
I assume for the return line, you meant to return a list, not a tuple. ghc
doesn't support a 600-tuple.
In any case, returning a list, I have verified that this problem exists in
ghc 6.10.3, for -O0 and -O2.

For -O0, it compiles and links fine, but gives this runtime message:

z: internal error: scavenge: unimplemented/strange closure type -1 @
0x2a95a8e000
   (GHC version 6.10.3 for x86_64_unknown_linux)
   Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
Abort

Maybe it is attempting to unroll these loops, even with -O0?

Dan

Henning Thielemann wrote:
Today a student has shown me a program that consists of a large 'do' block
for the list monad. The program looks like

   do x1 <- [0..3]
      x2 <- [0..2]
      ...
      x600 <- [0..5]
      guard (x1+x2+2*x3 >= 0)
      ...
      return (x1,x2,....,x600)

It was actually generated by another program. The results were:

 GHC-6.4 was not able to compile that program at all, because it stopped
because of memory exhaustion.
 GHC-6.8.2 finished compilation after two minutes but the program aborted
quickly because of a corrupt thunk identifier.
 GHC-6.10 not yet tested.
 Hugs-2006 executed the program without complaining and showed the first
result after a few seconds: (0,0,0,0,0,...,0).

Eventually the program must run on a Linux cluster with a not up-to-date
Linux kernel, that is, I suspect newer GHC versions cannot be used due to
the 'timer_create' problem. (At least, the 'cabal' executable that I
generated with a GHC-6.8.2 had this problem when running on the cluster
which reminded me on the problems with GHC-6.8 itself running on older Linux
kernels.)

Since the list monad sorts the variable values in lexicographic order
which is inappropriate for the considered problem, I recommended the use of
control-monad-omega. Luke, I hope this monad can cope with 600 variables.
:-)
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