Two syntax questions (newbie)

Szabolcs szhorvat at gmail.com
Mon Apr 23 11:24:28 CEST 2007


Thanks for the reply!

On Apr 23, 10:55 am, "Gabriel Genellina" <gagsl-... at yahoo.com.ar>
wrote:
> > or define a
> > function composition operator for functions that take a single
> > argument?
>
> You could use this:
>
> def chain(*args):
>    """Compose functions (assoc right).
>    last argument (args[-1]): argument to last function
>    args[0] .. args[-2]: functions taking a single argument
>    Returns args[0](args[1](...(args[-2]))(args[-1])
>    """
>    args = list(args)
>    data = args.pop(-1)
>    while args:
>      fn = args.pop(-1)
>      data = fn(data)
>    return data
>
> import random
> items = [random.randrange(100) for _ in range(20)]
> print chain(list, reversed, sorted, items)

This is already better. Is it possible to define function composition
as an operator and have something like (list at reversed@sorted)(items)
or (list*reversed*sorted)(items) ?

> I almost never use backslashes for line continuation. If you have an open
> (,[,{ continuation is implicit. If not, usually adding a heading ( is
> enough.
> That is, instead of
>
> x = a + b + \
>      c - d
>
> I'd use:
>
> x = (a + b +
>       c - d)

Thanks! This is very useful.

Szabolcs




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