Home Original page

[Python-Dev] product()

Guido van Rossum guido at python.org
Sat Oct 25 17:14:32 EDT 2003 
> it might be "alltrue" and "anytrue" -- the short-circuiting ones,
> returning the first true or false item found respectively, as in:
> 
> def alltrue(seq):
>     for x in seq:
>         if not x: return x
>     else:
>         return True
> 
> def anytrue(seq):
>     for x in seq:
>         if x: return x
>     else:
>         return False
> 
> these seem MUCH more generally useful than 'product' (but,
> I still opine, not quite enough to warrant being built-ins).

These are close to what ABC does with quantifiers.  There, you can
write

  IF EACH x IN sequence HAS x > 0: ...

ABC has the additional quirk that if there's an ELSE branch, you can
use x in it (as a "counter-example").

In Python, you could write this as

  if alltrue(x > 0 for x in sequence): ...

but the current design doesn't expose x to the else branch.

--Guido van Rossum (home page: http://www.python.org/~guido/)
More information about the Python-Dev mailing list