Re: [Haskell-cafe] Haskell maximum stack depth

Luke Palmer wrote:

On Feb 5, 2008 2:50 AM, Adrian Hey wrote:

...

I think it bites a lot less often than it otherwise would because most people will deliberately chose to use heap in preference to stack (at least when writing "eager" code) just to avoid the problem. But it still bites pretty often anyway with "lazy" code for unexpected reasons. Arguably such situations are indeed a "bug" more often than not, but I still think terminating the program unnecessarily (at 8M stack) is bad default policy.

Please, after all this, do give an example.

If you mean an example of coding style and choice of stack vs. heap, I already have.. http://www.haskell.org/pipermail/haskell-cafe/2008-January/038832.html If you mean an example of it biting with lazy code, this is discussed so often you'd be spoiled for choice if you search the mailing list archives. Here's a good one.. http://www.haskell.org/pipermail/haskell-cafe/2005-December/013521.html This example actually shows the problem twice. In one case it's solvable by using foldl' instead of foldl. In the other case there's nothing that can reasonably be done by the user short of editing the source code of Data.Map to provide a stricter insertWith function (which has now been added IIRC). The problem is repeated applying of a strict function lazily. When the result is eventually demanded the stack "blows up". In the mean time you sometimes have an unnecessary space (heap) leak too (with counters for example). Regards -- Adrian Hey