Neil Mitchell wrote:
Hi Istarex,
Does Haskell have a maximum stack depth restriction like Java & Python, or is it only limited by the maximum stack available on the system (i.e. what would be available to a C program)?
You are probably thinking that recursive functions use up program stack, and hence the stack depth bounds the amount of recursion. In Haskell, that isn't the case. Haskell is lazily evaluated, and has tail recursion, which means that you rarely run into a problem with exceeding the stack depth. In GHC the "stack" is stored in the heap area of memory, so is not limited to the C stack, but can be set at runtime with a flag (+RTS ... something ...) - but you won't need to.
Sorry, but I think that's a very misleading answer to give to someone (who's presumably a noob). The answer is that no such limit is defined in the standard, for the obvious reason that the standard does not presume anything about runtime implementation, not even the presence of a "stack". ghc uses a pretty conventional stack AFAIK, and it is arbitrarily limited, but you can change the limit with +RTS options. Also, stack "overflows" are a pretty common cause of program failure IME, not at all rare. At least, far more common than whatever error message you get from heap exhaustion (can't even remember the last time I saw one of those). Regards -- Adrian Hey