[Python-Dev] Re: Quantifiers Was: Trinary Operators

[Raymond Hettinger]

[Oren Tirosh]
> > > Oh dear. If you are really going to do these these cutesy English-like
> > > expressions I'd have to resurrect my old proposal of:
> > > 
> > > if CONDITION for some NAME in ITERABLE:
> > > if CONDITION for every NAME in ITERABLE:
> > > if CONDITION for no NAME in ITERABLE:

[Samuele Pedroni]
> I would not dislike to have expression forms equivalent to applications of
> 
> def every(pred,l):
>    for x in l:
>      if not pred(x): return False
>    return True
> 
> def some(pred,l):
>    for x in in l:
>      if pred(x): return True
>   return False
> 
> def such(pred,l,otherwise=None):
>    for x in in l:
>      if pred(x): return x
>   return otherwise
>   
> as list comprehension is equivalent to map and filter.

BTW, quantifiers can be efficiently implemented 
using functions in the itertools module. I'll add an 
example to the docs.


Raymond Hettinger