What can you do in LISP that you can't do in Python

mikel evins himself at mikelevins.com
Thu May 24 16:14:38 CEST 2001


> > (let* ((count 0)
> >        (incrementer #'(lambda () (setq count (1+ count)))))
> >   (defmacro counting-setq (var val)
> >     `(progn
> >        (funcall ,incrementer)
> >        (setq ,var ,val)
> >        ,count)))
>
> > What it does is this: it defines a new version of SETQ called
> > 'counting-setq'. This new operation does the same thing that SETQ does:
it
> > sets the value of a variable. But it does something else, too: it counts
how
> > many times you call it and saves the current count in a variable that
nobody
> > but counting-setq can see or affect. When it sets a variable it
increments
> > the current count and then returns it.

That's what I get for spewing. :-)

How, in Python, do you

1) build new syntax

2) capture a lexical environment

?







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