Now try writing two mutually-recursive functions. In Scheme (as I
understand it) that will get optimized into a jump from one function
to the other, while in Clojure it will use the stack.
On Jan 26, 1:10 pm, Armando Blancas <armando_blan...@yahoo.com> wrote:
> From SICP: "With a tail-recursive implementation, iteration can be
> expressed using the ordinary procedure call mechanism". As I
> understand this, a tail call is a loop with functional notation but
> not actually a function call. That's why I find this issue difficult
> to follow, since loops are internal details of a function/method and
> don't get involved with calls, stack frames, access security, or how
> the jit-compiled code may or may not be optimized. So there's
> something key here that I'm missing.
>
> In a little project of mine I plan on doing this (hand-coded with ASM
> as my compiler doesn't do TCO yet). That seems to work but I wonder
> what issues may come up.
>
> int fact(int n, int r) {
> if (n == 0) return r;
> else return fact(n-1, n*r);}
>
> 0: iload_0
> 1: ifne 6
> 4: iload_1
> 5: ireturn
> 6: iload_0
> 7: istore_2 // temp for n
> 8: iload_2
> 9: iconst_1
> 10: isub
> 11: istore_0
> 12: iload_2
> 13: iload_1
> 14: imul
> 15: istore_1
> 16: goto 0
>
> On Jan 26, 11:20 am, Luc Prefontaine <lprefonta...@softaddicts.ca>
> wrote:
>
> > From what I recall from a previous thread it would require so much byte
> > code tweaking that
> > Hot Spot optimizations would become useless.
>
> > You can search the mailing list, you will find a couple of instructive
> > discussions
> > about this.
>
> > Luc P.
>
> > On Wed, 26 Jan 2011 10:01:04 -0800
>
> > Raoul Duke <rao...@gmail.com> wrote:
> > > On Wed, Jan 26, 2011 at 7:41 AM, Michael Gardner
> > > <gardne...@gmail.com> wrote:
> > > > However, the JVM does not support tail-call optimization.
> > > > Apparently Clojure can't support implicit TCO without support from
> > > > the JVM
>
> > > always wondered about that also wrt scala etc., am under the
> > > impression that it is implementable, but it would be too slow?
>
> > --
> > Luc P.
>
> > ================
> > The rabid Muppet
>
>
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