[Python-ideas] list / array comprehensions extension

[Masklinn]

On 2011-12-15, at 19:02 , Michael Foord wrote:
> Well, the new tuple unpacking syntax makes it easy to work with the head
> and tail of a sequence:
> 
>    head, *rest = some_sequence
>   *rest, tail = some_sequence
> 
> This syntax provides a corollary:
> 
>    some_sequence = (head, *rest)
>    some_sequence = (*rest, tail)
> 
> Tuple unpacking like this being the equivalent of car and cdr, with the
> corollary being the equivalent of cons. (Given my limited understanding of
> these operations.)
Even more so with Py3's unpacking supporting more than just head and tail:

    >>> a, b, *c, d, e = range(15)
    >>> a
    0
    >>> b
    1
    >>> d
    13
    >>> e
    14
    >>> c
    [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]

Alexander's syntax would be nicely parallel to this.

On the other hand, much as Steven I'm not sure how useful it is, especially for tuples.