[Python-ideas] More useful slices

[Eugene Toder]

On Sun, Feb 1, 2015 at 10:13 AM, Todd <toddrjen at gmail.com> wrote:

> Although slices and ranges are used for different things and implemented
> differently, conceptually they are similar: they define an integer sequence
> with a start, stop, and step size.  For this reason I think that slices
> could provide useful syntactic sugar for defining ranges without
> sacrificing clarity.
>
> The syntax I propose is simply to wrap a slice in parentheses.  For
> examples, the following pairs are equivalent:
>
> range(4, 10, 2)
> (4:10:2)
>
> range(3, 7)
> (3:7)
>
> range(5)
> (:5)
>
> This syntax should not be easily confused with any existing syntax.
> Slices of sequences use square brackets, dictionaries use curly braces, and
> function annotations only appear in function declarations.  It is also
> considerably more compact than the current range syntax, while still being
> similar to a syntax (slicing) all python users should be familiar with.
>
It may be too late for this, but I like it. We can also elide extra
parentheses inside calls, like with generator expressions:
sum(4:10:2)

Also, using list comprehension to generator expression analogy, we can have
[4:10:2]
which produces a list instead of a range object. Other than for
completeness this does not seem very useful, though.


Eugene
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