[Haskell-cafe] Trouble finding exception source

Judah Jacobson judah.jacobson at gmail.com
Wed Feb 27 02:01:56 EST 2008

Hi Denis,

I was unable to run your program; it looks like there's a missing
module 'Properties'.  To include it in the sdist you probably need to
add it under the other-modules field in the .cabal file.


2008/2/26 Denis Bueno <dbueno at gmail.com>:
> Hi all,
>  I've got some code crashing with "Prelude.foldr1: empty list".  In
>  GHCi, the code uses too much memory (I kill it after it consumes 1GB)
>  to be able to use :trace and :history, but I just found out about the
>  -xc RTS option.  I tried that, and I get the following:
>     <GHC.List.CAF>dsat: Prelude.foldr1: empty list
>  Now, manually going through GHC.List
>  (http://haskell.org/ghc/docs/latest/html/libraries/base/src/GHC-List.html)
>  I only found one CAF, namely prel_list_str, at the bottom of the file.
>   However, it is late and I quite possibly missed something.  This CAF,
>  of course, doesn't seem a likely culprit.  I also stumbled on some
>  discussion of the explicit call stack
>  (http://hackage.haskell.org/trac/ghc/wiki/ExplicitCallStack/StackTraceExperience)
>  which exemplifies the behavior I've found, but doesn't seem to suggest
>  a way to fix it.
>  I'm developing on GHC 6.8.2.  I've attached my code, the output of a
>  cabal sdist, which requires parse-dimacs [0] and bitset [1] (both
>  cabalised) to build.  If you build the executable (with profiling),
>  you should see my behavior by running:
>     ./dist/build/dsat/dsat -verify +RTS -xc
>  I know that the problem is somewhere in the "Backtracking" section, in
>  the backJump function.  But I don't know where.
>  Any help is appreciated.
>  --
>                               Denis
>  [0] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/parse-dimacs-1.0.1
>  [1] http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bitset-0.5
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