On 2008.02.26 23:13:59 -0500, Denis Bueno <[EMAIL PROTECTED]> scribbled 7.4K characters: > 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
Fortuitously, I recently came across a bunch of bioinformatics software in Haskell. One of the libraries was called 'interlude', and it claims to be able to give line locations for errors in the Prelude. I was intending to upload them all as a group once I'd finished, but you might be able to make use of it here. You can find it here: <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/interlude-0.1.1>. If it does work out for you, be sure to let me know. I haven't run across any Prelude errors in my code since I installed it, so I haven't really tried it out. -- gwern brigand Investigation Firewalls Galil NTIS TDYC Yukon Morse Jazeera INR
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