Hi folks. I have a piece of Haskell code that's been laying around on my computer for about a year, and I recently decided to dust it off. The problem is that it used to work fine, but in the interim (in which I both upgraded OS versions/GHC versions and went from 32 bit to 64 bit) the code stopped working reliably. It tends to work OK for small data sets, but with larger data sets it exhibits one of three bad behaviors: 1) A segfault, 2) An "Error in array index" error, or 3) The following runtime error: internal error: evacuate: strange closure type 5060208 (GHC version 7.0.3 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Aborted It complies OK, although with optimization turned on it gives me a "has one call pattern, but the limit is 0" error, but my understanding is that this shouldn't really be an issue. I'd like to figure out what this issue is, but while I understand a bit about the language itself, with my knowledge of GHC and the way it works I don't really know where to begin. (The strange non-deterministic nature of the problem makes me wonder if it could be something not related to Haskell, such as a hardware or memory error. Is this possible or likely?) Any guidance/pointers would be very much appreciated. Thanks. -Mark