[Python-Dev] Trinary Operators

[Samuele Pedroni]

From: "Guido van Rossum" <guido@python.org>
> > 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:
> > 
> > Please, dont make me do that ;-)
> 
> An if-expression is frequently requested, and I expect people will
> continue to ask for it until I add one :-)
> 
> Who (besides you) has ever asked for generalized quantifiers?  They
> were in ABC, with slightly different syntax: 
> 

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.