Hrvoje Niksic wrote:
Common Lisp behaves similar to Python in this
regard:
* (loop for i from 0 to 2 collect (lambda () i))
I wouldn't call the CL loop macro the equivalent of
a for-loop. It's more like a while-loop.
The Lisp equivalent of a Python for-loop would be
to use one of the mapping functions. Then, since
the loop body is a lambda, you get a new scope for
each iteration automatically.
I don't think it has anything to do with variable leaking out of the
loop.
That's right, it doesn't. If I were designing a
for-loop from scratch, I wouldn't let it leak, but
that part seems to be necessary for backwards
compatibility.
> In contrast, Scheme regards
iteration as a special case of recursion, and R5RS "do" prescribes
assigning loop variables to "fresh locations" to match what recursion
normally does.
I'd say it prescribes that because it's useful
behaviour, not because it has anything to do with
recursion.
--
Greg
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