[Python-Dev] accumulator display syntax
Guido van Rossum
guido at python.org
Tue Oct 21 16:55:37 EDT 2003
> Well, calling it an iterator Aussonderungsaxiom would continue emphasizing
> the wrong thing <wink>.
> "Set comprehensions" in a programming language originated with SETL,
> and are named in honor of the set-theoretic Axiom of Comprehension
> (Aussonderungsaxiom). In its well-behaved form, that says roughly
> that given a set X, then for any predicate P(x), there exists a
> subset of X whose elements consist of exactly those elements x of X
> for which P(x) is true (in its ill-behaved form, it leads directly
> to Russell's Paradox -- the set of all sets that don't contain
> So "comprehension" emphasizes the "if" part of list comprehension
> syntax, which often isn't the most interesting thing. More
> interesting more often are (a) the computation done on the objects
> gotten from the for-iterator, and (b) that the results are generated
> one at a time.
> Put that all in a pot and stir, and the name "generator expression"
> seems natural and useful to me. In the Icon language, *all*
> expressions are generators, so maybe I'm biased by that. OTOH, "the
> results are generated one at a time" is close to plain English, and
> "generator expression" then brings to my mind an expression capable
> of delivering a sequence of results.
Thanks for an independent validation of "generator expressions"! It's
a perfect term.
> Or you could call it an Orlijn flourish.
No, that term is already reserved for something else (the details of
which I'll spare you, as they involve intimate details about toddler
--Guido van Rossum (home page: http://www.python.org/~guido/)
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