Michael> There is only one context where this is true: When you try to emulate Michael> tail recursion *in C procedure calls* via a trampoline. Optimizing Michael> Scheme-to-C compilers get around this in most cases, however. Let me Michael> again mention that Scheme compilers are among the best-optimizing Michael> compilers for higher-level languages, and often achieve code Michael> performance comparable to C. Which compilers do this? I know Stalin is very good, but it compiles to C as does gambit, so these must have the performance hit. Ray> I guess my question is, if things were written recursively, how a big Ray> a stack would we use and would that be big enough to matter? Michael> I don't even understand the question. Tail calls don't use stack I meant if it wasn't tail-recursive. I understand the desire and need for tail-recursive algorithms, and I think we should strive to have it. Ray