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[Python-Dev] syntactic support for sets

Donovan Baarda abo at minkirri.apana.org.au
Mon Feb 6 15:09:18 CET 2006 
On Fri, 2006-02-03 at 11:56 -0800, Josiah Carlson wrote:
> Donovan Baarda <abo at minkirri.apana.org.au> wrote:
[...]
> > Nuff was a fairy... though I guess it depends on where you draw the
> > line; should [1,2,3] be list(1,2,3)?
> 
> Who is "Nuff"?

fairynuff... :-)

> Along the lines of "not every x line function should be a builtin", "not
> every builtin should have syntax".  I think that sets have particular
> uses, but I don't believe those uses are sufficiently varied enough to
> warrant the creation of a syntax.  I suggest that people take a walk
> through their code. How often do you use other sequence and/or mapping
> types? How many lists, tuples and dicts are there?  How many sets? Ok,
> now how many set literals?

The absence of sets in early Python, the requirement to "import sets"
when they first appeared, and the lack of a set syntax now all mean that
people tend to avoid using sets and resort to lists, tuples, and "dicts
of None" instead, even though they really want a set. Anywhere you see
"if value in sequence:", they probably mean sequence is a set, and this
code would run much faster if it really was, and might even avoid
potential bugs because it would prevent duplicates...

-- 
Donovan Baarda <abo at minkirri.apana.org.au>
http://minkirri.apana.org.au/~abo/
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