> On 2018 Mar 29 , at 12:06 p, Chris Angelico <[email protected]> wrote:
>
> On Fri, Mar 30, 2018 at 3:00 AM, Stephan Houben <[email protected]> wrote:
>> Perhaps one day we will be able to use
>>
>> â
>>
>> for the empty set.
>> That would actually match conventional notation.
>>
>
> Maybe, but that symbol generally means the unique immutable empty set
> in mathematics, so a closer equivalent would be frozenset(), in the
> same way that () gives you a singleton immutable empty tuple. But yes,
> I would like to some day have a literal for an empty set. Just not
> "{}".
>
Mathematically, {1,2,3} is a unique, immutable set, too. {1,2,3} \union {4}
doesn't modify {1,2,3}; it's just another way to represent another unique
immutable set {1,2,3,4}. So I don't seen any problem (aside from the general
resistance
Unicode) with using â
to mean set().
However, just as string literals take a variety of prefixes (r, u, b, f), why
can't set/dict literals?
d{} == {} == dict()
d{"a": 2} == {"a": 2} == dict(a=2)
s{1,2,3} == {1,2,3} == set([1,2,3])
s{} == set()
f{} == frozenset()
f{1,2,3} == frozenset({1,2,3})
(I vaguely recall hearing a proposal to use o{...} for ordered dicts, so maybe
this has already been considered. The only information I can find on set
literals,
though, assume {...} as a foregone conclusion, with various wrapped symbols like
{/}, {@}, and {:} suggested to complement {}.)
If we did use â
for an empty set, then fâ
could be the empty frozen set.
--
Clint
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