[Python-Dev] Any reason that any()/all() do not take a predicateargument? (original) (raw)

Bill Janssen janssen at parc.com
Sat Apr 15 21:51:59 CEST 2006

>> seq = [1,2,3,4,5] >> if any(seq, lambda x: x==5): >> ... >> >> which is clearly more readable than >> >> reduce(seq, lambda x,y: x or y==5, False) > > How about this? > > if any(x==5 for x in seq):

Aren't all of these equivalent to: if 5 in seq: ...

Yeah, but you can't do more complicated expressions that way, like

  any(lambda x: x[3] == "thiskey")

I think it makes a lot of sense for any and all to take optional predicate function arguments.

But perhaps the syntax should be:

  X in SEQ

If X is a predicate function, it gets called to determine "equals"; if an expression or other object, the normal rules apply. Of course, then you couldn't look for a function in a set of functions...

I suppose

  (len([x for x in SEQ if PRED(x)]) > 0)

will suffice for now. Obvious enough, Martin?

Bill

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