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Re: Lexical binding and macros.


From: Stefan Monnier
Subject: Re: Lexical binding and macros.
Date: Thu, 16 Dec 2010 16:59:59 -0500
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.50 (gnu/linux)

>> Additionally to what Pascal already explained, I'll add that,
>> lexical-let, like `loop' are relatively heavy macros, so you
>> definitely don't want to run them interpreted (where the macro is
>> re-expanded each time).
> Why would they be reexpanded each time?

Because it's easier to implement it that way in a pure interpreter.

> They are macros.  Their expansion is done once and merely evalled
> each time.
> Or do I misunderstand something here?

Their expansion *can be* done once (which is what happens when you
byte-compile), but the interpreter doesn't bother with
such optimizations.


        Stefan


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