What's do list comprehensions do that generator expressions don't?

[Terry Reedy]

The question under these circumstances is then: do you want bare
genexp to mean something? Right now, it's a syntax error. But there's
no reason you couldn't have:

y = x for x in stuff

assign a generator object to y.

Since this was considered, there is a reason why we don't have this. As I
remenber, but vaguely, Guido's reasoning was both stylistic and technical,
but you'd have to check the archives for more.

Terry J. Reedy

 

[Reinhold Birkenfeld]

The question under these circumstances is then: do you want bare
genexp to mean something? Right now, it's a syntax error. But there's
no reason you couldn't have:

y = x for x in stuff

I like

y = (x for x in stuff)

as it is, it's way more readable.

Reinhold

 

[Jeremy Bowers]

Right. But that shouldn't be hard to do. Let genexp stand for a a
generator expression/list comprehension without any brackets on it at all.
Then [genexp] is the syntax to expand the list. [(genexp)] is the syntax
to create a list of one element - a generator object. foo(genexp) will do
the right thing.

In other words, everything as it is today, only with different
implementations under the hood.

Rolling back around to the original point, I don't see any reason to ban
[x for x in thing], changing current practice, when it is so easy to keep
it. [(x for x in thing)] is also current practice (perhaps "bad style" in
some sense, but definately possible in 2.4), and I don't think there is a
good reason to change that, either.

 

[Bengt Richter]

Since this was considered, there is a reason why we don't have this. As I
remenber, but vaguely, Guido's reasoning was both stylistic and technical,
but you'd have to check the archives for more.

Because it is too reminiscent of a lambda expression assignment? ;-)

Regards,
Bengt Richter