[Haskell-cafe] Obscure weirdness

Marcin Kosiba marcin.kosiba at gmail.com
Sat Jun 20 15:19:36 EDT 2009

On Saturday 20 June 2009, Andrew Coppin wrote:
> OK, so here's an interesting problem...
> I've been coding away all day, but now my program is doing something
> slightly weird. For a specific input, it summarily terminates. The
> registered exception handler does not fire. There is no output to stdout
> or stderr indicating what the problem is. It just *stops* half way
> through the printout.
> Weirder: If I run it in GHCi, then GHCi itself terminates. (I didn't
> think you could *do* that!)
> It's not as if my program is anything unusual. There are no unsafe
> functions. No FFI. Nothing. Just regular high-level Haskell.
> Is this a known bug in GHC 6.10.1? Will upgrading fix it? (Obviously,
> it's quite a lot of work to change GHC.) Suffice it to say that my
> program is quite big and complicated; it worked fine when it was still
> small and simple. ;-)

	With the information you've provided it's hard to even guess. At least take a 
look at your app's RAM usage -- it just may be that its allocating too much 
memory and the OOM killer is killing it (if you're running linux, that is).
	You may also want to try the GHCi debugger [1] to find out where the program 
crashes. The last thing I'd do is blame it on ghc/ghci, but as always -- such 
a possibility exists.

	Marcin Kosiba

[1] http://www.haskell.org/ghc/docs/latest/html/users_guide/ghci-debugger.html

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