Is there "let binding" in Python?
jacek.generowicz at cern.ch
Wed Sep 17 13:49:59 CEST 2003
Rob Hunter <rhunter007 at yahoo.com> writes:
> Is there an equivalent to Scheme's LET in Python?
> LET creates a new binding in the current
> environment. For example, here's some Scheme
> (let ((x 3))
> (let ((f (lambda (arg) (* arg x))))
> (let ((x 4))
> (f 5))))
> So, this program, which also tests that Scheme
> has correct scoping, returns 15.
Sorry, never heard of "correct" scoping[*]. I've heard of lexical and
dynamic scoping though, and, to me, your code shows that Scheme has
> And in Python, I can write an equivalent program
> that does correctly return 15, but I have to use
> what, in Scheme, we call "left-left lambda"--a
> way of simulating LET. Or rather, LET is
> syntactic sugar for left-left lambda.
A long, time ago (Python 2.0), Python only had 3 scopes: local, global
and builtin. Now it has nested scopes of arbitrary depth (still
wrapped inside global and builtin), but I'm not expecting "let" to
appear anytime soon.
[*] But given that you are formulating your question from a Scheme
perspective, it's not really surprising that you call it
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