[Python-Dev] Naming comprehension syntax [was Re: Informal educator feedback on PEP 572 ...]

Brett Cannon brett at python.org
Mon Jul 9 15:57:20 EDT 2018

On Mon, 9 Jul 2018 at 12:05 Guido van Rossum <guido at python.org> wrote:

> I think this is worth a try.

How far do we want to go with this? Update the docs? Update the grammar
and/or code? I think the former is probably good enough for now to see if
it takes, and if it does then we can talk about updating code to not
confuse people.

> On Mon, Jul 9, 2018 at 12:04 PM Chris Barker - NOAA Federal <
> chris.barker at noaa.gov> wrote:
>> TL;DR-
>> +1 on advocating the term “generator comprehension” as a synonym for
>> “generator expression” in future documentation and instructional
>> materials.
>> The long version:
>> If we were starting from scratch, maybe it would makes sense to use “
>> builder” or something else, rather than comprehension. But we’re  not
>> starting from scratch.
>> And “list comprehension” has become a pretty universal (or at least
>> common) term in the python world. So we really can’t expect to re-name
>> that.
>> And despite the term having its roots in an esoteric corner of
>> mathematics, I’ve never seen anyone confused by it — it’s just a new
>> word for a new thing to most folks.
>> Which is actually why “generator expression” is a bit confusing — it
>> seems to have more in common with comprehensions than with generators
>> (As in: the things functions with a yield in them produce)
>> In fact, the term “generator” is a bit confusing itself — due to it
>> being a common English word, it seems to refer to the generic idea of
>> “a thing that generates values on the fly”, which, of course it can be
>> in Python. But it actually is a specific type. And you can make a
>> “thing that generates values in the fly” with a regular class that
>> follows the iterator protocol.
>> So re-using the word in “generator expression” just adds a bit to the
>> confusion. (Even though it’s technically correct, it does “make” an
>> actual generator object, doesn’t it? (On a phone, so I can’t check)
>> but that’s kind of an implementation detail.
>> Also: if you google: “python list comprehension” you get a LOT of hits
>> to tutorials, etc.
>> So it is WAY too late to change that name.
>> When you google “python generator expression” the top hit is the
>> python docs, and the next few are about comparing generator
>> expressions and list comprehensions.
>> So I think we could start a new naming scheme for those.
>>  ‘cause then we’d get lost of questions about the difference between
>> generator expressions and generator comprehensions ;-)
>> -CHB
> --
> --Guido van Rossum (python.org/~guido)
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