[erlang-questions] Idiomatic Erlang, style/performance question
Fri Jun 20 10:35:25 CEST 2008
Dominic Williams wrote:
> ROK wrote:
>> I prefer the term "Tail-Call Optimisation" because it is more accurate.
>> The idea (as explained in "Lambda - the Ultimate Goto") is that if the
>> dynamically last thing a function does (in any language) is to return
>> the result of another function call, then there is no point in keeping
>> the current stack frame. You might as well arrange for the new
>> function to return directly to the original caller. Think of *all*
>> tail calls as "argument binding + GOTO".
> Is the optimisation possible even when the tail call is not to the same
>>> power(N, P) when is_integer(P), P >= 0 ->
>>> ipower(N, P, 1);
>>> power(N, P) when is_integer(P), P < 0 ->
>>> 1/ipower(N, -P, 1).
>> The first call here is a tail call, the second is not.
> As I wrote in a previous post, I thought that there was no optimisation
> here, because it is not a /recursive/ tail-call. Am I wrong? What is the
> case for Erlang, in particular?
Erlang optimizes tail calls, not necessarily recursive ones.
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