Re: Compile time executed functions

[Florian Weimer <fw@deneb.enyo.de>]

Ted Dennison<dennison@telepath.com> writes:

> >You build the function (or a lambda expression) using the usual
> >methods, and then call COMPILE on it.  Simple, isn't it? ;-)

> But that just generates code for the function, right?

Yes, but this way, values can be computed prior to run time which
appear to be constants (even during compile time) but are in fact not.

> It doesn't actually execute the code, find the resulting return
> value, then place that value in a data object *during compile time*.

I think the concepts 'compile time' and 'run time' are a bit blurry
with Common Lisp (a CL enthusiast would protest, of course), simply
because we're used to the fact that 'run time' follows 'compile time',
and not the other way round.  With CL (and FORTH as well, and most
Java implementations), this is no longer true.

> To do that, you'd have to use define-compiler-macro.

Or some eval-when construct, I think.