From: Alexandru Harsanyi
Subject: efficiency of let vs. let*
Date: Thu, 29 Jul 2004 13:53:48 +0000
Message-ID: <m2ekmuvrz9.fsf@Alex.local>

Just out of curiosity I looked at the eval implementation for GNU
Emacs (eval.c file), and noticed that the implementation of let* seems
more efficient that the implementation of let.  The later involves
allocating a temporary array to hold the values from evaluating the
forms before binding them to the variables.

I'm wondering if this is true in all LISP implementations?

I don't think the speed difference between let and let* very big, so
it doesn't really matter, but I'm just curious :-)

Thanks,
Alex.

From: Hannah Schroeter
Subject: Re: efficiency of let vs. let*
Date: Thu, 29 Jul 2004 14:10:32 +0000
Message-ID: <ceb0go$n10$1@c3po.use.schlund.de>

Hello!

Alexandru Harsanyi  <········@mac.com> wrote:

>Just out of curiosity I looked at the eval implementation for GNU
>Emacs (eval.c file), and noticed that the implementation of let* seems
>more efficient that the implementation of let.  The later involves
>allocating a temporary array to hold the values from evaluating the
>forms before binding them to the variables.

>I'm wondering if this is true in all LISP implementations?

>I don't think the speed difference between let and let* very big, so
>it doesn't really matter, but I'm just curious :-)

In a compiler, the speed difference should be none. Except that you
could get littler freedom for instruction scheduling, if in a let*
later bindings refer to earlier ones.

That's speaking about lexical lets at least.

Kind regards,

Hannah.