Python syntax in Lisp and Scheme

[Terry Reedy]

"Pascal Costanza" <costanza at web.de> wrote in message
news:blu4q0$1568$1 at f1node01.rhrz.uni-bonn.de...
> What about dealing with an arbitrary number of filters?

[macro snipped]

What about it?  Using macros for somewhat simple functions stikes me
as overkill.

> An example:
>
>  > (predicate-collect '(-5 -4 -3 -2 -1 0 1 2 3 4 5)
>      (function evenp)
>      (lambda (n) (< n 0))
>      (lambda (n) (> n 3)))
> (-4 -2 0 2 4)
> (-5 -3 -1)
> (5)
> (1 3)

In Python:

def  multisplit(seq, *preds):
    predn = len(preds)
    bins = [[] for i in range(predn+1)]
    predpends = [(p,b.append) for (p,b) in zip(preds,bins)]
    rpend = bins[predn].append
    for item in seq:
        for pred,pend in predpends:
            if pred(item):
                pend(item)
                break
        else: rpend(item)
    return bins

multisplit(range(-5,6), lambda i: not i%2, lambda i: i<0, lambda i:
i>3)

[[-4, -2, 0, 2, 4], [-5, -3, -1], [5], [1, 3]]

Terry J. Reedy