PEP 308: Pep Update
Anders J. Munch
andersjm at inbound.dk
Sun Mar 2 20:54:27 CET 2003
"Sheila King" <usenet at thinkspot.net> wrote:
> On Thu, 27 Feb 2003 23:31:03 +0100, "Anders J. Munch"
<andersjm at inbound.dk>
> wrote in comp.lang.python in article
> <Qmw7a.98775$Hl6.9497242 at news010.worldonline.dk>:
> > Pop quiz: What is the value of this alternate universe list
> > comprehension expression?
> > [for x in (1,2): for y in (-1,+1): x*y]
> I find this one very confusing.
It's just a nested for-loop. Remove the braces and add an indent and
you get something that you can actually run at the interpreter prompt,
to print four values:
for x in (1,2):
for y in (-1,+1): x*y
>Was your intent that it should be clear and
> obvious? Or was your intent to show how this type of thing could be
> confusing? I was not sure.
I showed a list comp. syntax that looks like a for-loop to illustrate
that Python list comprehensions do not look like for loops. For-loops
have the repeated stuff to the right or below the "for X in V" part,
list comprehensions don't.
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