builtin set literal

[=?ISO-8859-1?Q?Sch=FCle_Daniel?=]

Hello,

lst = list((1,2,3))
lst = [1,2,3]

t = tupel((1,2,3))
t = (1,2,3)

s = set((1,2,3))
s = ...

it would be nice feature to have builtin literal for set type
maybe in P3 .. what about?
s = <1,2,3>

Regards, Daniel

[faulkner]

Re: builtin set literal

On Feb 14, 11:55 am, Schüle Daniel <u...@rz.uni-karlsruhe.dewro te:

Hello,
>
lst = list((1,2,3))
lst = [1,2,3]
>
t = tupel((1,2,3))
t = (1,2,3)
>
s = set((1,2,3))
s = ...
>
it would be nice feature to have builtin literal for set type
maybe in P3 .. what about?
s = <1,2,3>
>
Regards, Daniel

sets aren't quite that useful or common. just use a list.
and '<' and '>' already have syntactic meanings.
and that would make python look more like C++, which nobody wants.

[Steven Bethard]

Re: builtin set literal

Schüle Daniel wrote:

Hello,
>
lst = list((1,2,3))
lst = [1,2,3]
>
t = tupel((1,2,3))
t = (1,2,3)
>
s = set((1,2,3))
s = ...
>
it would be nice feature to have builtin literal for set type
maybe in P3 .. what about?
s = <1,2,3>

In Python 3.0, this looks like::

s = {1,2,3}

More info here:

http://www.python.org/dev/peps/pep-3100/

STeVe

[=?ISO-8859-1?Q?Sch=FCle_Daniel?=]

Re: builtin set literal

faulkner schrieb:

On Feb 14, 11:55 am, Schüle Daniel <u...@rz.uni-karlsruhe.dewro te:

>Hello,
>>
>lst = list((1,2,3))
>lst = [1,2,3]
>>
>t = tupel((1,2,3))
>t = (1,2,3)
>>
>s = set((1,2,3))
>s = ...
>>
>it would be nice feature to have builtin literal for set type
>maybe in P3 .. what about?
>s = <1,2,3>
>>
>Regards, Daniel

>
sets aren't quite that useful or common. just use a list.
and '<' and '>' already have syntactic meanings.

well, I thought about this
the empty set <has the meaning of != now
as far as I remember is <depricated and will disappear
When they are gone in P3000, <could be reused as empty set.

and that would make python look more like C++, which nobody wants.

I dont think that actually many people fear this.
we have {} for dicts and I doubt anybody mistake them for C++ brakets.

In my previuos post I forgot to mention

d = dict()
d = {}

s = set()
s = <>

why not, on the first sight everybody will see ... here our
algorithmus deals with unique things/objects ... put in a set.

Regards, Daniel

[=?ISO-8859-1?Q?Sch=FCle_Daniel?=]

Re: builtin set literal

Steven Bethard schrieb:

Schüle Daniel wrote:

>Hello,
>>
>lst = list((1,2,3))
>lst = [1,2,3]
>>
>t = tupel((1,2,3))
>t = (1,2,3)
>>
>s = set((1,2,3))
>s = ...
>>
>it would be nice feature to have builtin literal for set type
>maybe in P3 .. what about?
>s = <1,2,3>

>
In Python 3.0, this looks like::
>
s = {1,2,3}

jepp, that looks not bad .. as in a mathe book.
the only disadvantage I see, that one may confuse it with a dict.

Regards, Daniel

[Steven Bethard]

Re: builtin set literal

Schüle Daniel wrote:

Steven Bethard schrieb:

>Schüle Daniel wrote:

>>it would be nice feature to have builtin literal for set type
>>maybe in P3 .. what about?
>>s = <1,2,3>

>>
>In Python 3.0, this looks like::
>>
> s = {1,2,3}

>
jepp, that looks not bad .. as in a mathe book.
the only disadvantage I see, that one may confuse it with a dict.

Perhaps with a very cursory inspection. But the lack of any ':'
characters is a pretty quick clue-in.

STeVe

[=?ISO-8859-1?Q?Sch=FCle_Daniel?=]

Re: builtin set literal

[...]

>>In Python 3.0, this looks like::
>>>
>> s = {1,2,3}

>>
>jepp, that looks not bad .. as in a mathe book.
>the only disadvantage I see, that one may confuse it with a dict.

>
Perhaps with a very cursory inspection. But the lack of any ':'
characters is a pretty quick clue-in.

there is one a bigger disadvantage though
{} empty set clashes with empty dict {}
set() still must be used to generate the empty set
or a hack like
s = {None}.clear()

I think something like {-} as the substitution for empty set
will seem bit to perlish for most of us? :)

Regards, Daniel

[MRAB]

Re: builtin set literal

On Feb 15, 4:12 pm, Schüle Daniel <u...@rz.uni-karlsruhe.dewro te:

[...]
>

>In Python 3.0, this looks like::

>

> s = {1,2,3}

>

jepp, that looks not bad .. as in a mathe book.
the only disadvantage I see, that one may confuse it with a dict.

>

Perhaps with a very cursory inspection. But the lack of any ':'
characters is a pretty quick clue-in.

>
there is one a bigger disadvantage though
{} empty set clashes with empty dict {}
set() still must be used to generate the empty set
or a hack like
s = {None}.clear()
>
I think something like {-} as the substitution for empty set
will seem bit to perlish for most of us? :)
>

What about "{,}"? For consistency "(,)" and "[,]" might also have to
be permissible, and maybe even "{:}" for an empty dict. Or perhaps not.

[Raymond Hettinger]

Re: builtin set literal

>What about "{,}"? For consistency "(,)" and "[,]" might

>also have to be permissible, and maybe even "{:}" for an
>empty dict.

The notion of a set literal was rejected in PEP 218,
http://www.python.org/dev/peps/pep-0218/ . One of the reasons for the
rejection was that the small benefit of a literal notion was more than
offset by the attendant need for syntactical atrocities like those
listed above.


Raymond

[bearophileHUGS@lycos.com]

Re: builtin set literal

Raymond Hettinger:

One of the reasons for the
rejection was that the small benefit of a literal notion was more than
offset by the attendant need for syntactical atrocities like those
listed above.

{:} for empty dict and {} for empty set don't look too much atrocious
to me.


Note: the language Fortress, that in graphic modality uses unicode for
its sources, has many collection literals (6 or more, you can see 3 of
them at page 21):

http://research.sun.com/projects/plrg/PLDITutorialSlides9Jun2006.pdf

Bye,
bearophile

[=?ISO-8859-1?Q?Sch=FCle_Daniel?=]

Re: builtin set literal

{:} for empty dict and {} for empty set don't look too much atrocious
to me.

this looks consistent to me

[Steven Bethard]

Re: builtin set literal

Schüle Daniel wrote:

>{:} for empty dict and {} for empty set don't look too much atrocious
>to me.

>
this looks consistent to me

Yes, a lot of people liked this approach, but it was rejected due to
gratuitous breakage. While Python 3.0 is not afraid to break backwards
compatibility, it tries to do so only when there's a very substantial
advantage. I guess enough people felt that having a shortcut for set()
was less important than keeping the current spelling of dict() the same.

STeVe

[Paul Rubin]

Re: builtin set literal

Steven Bethard <steven.bethard @gmail.comwrite s:

Yes, a lot of people liked this approach, but it was rejected due to
gratuitous breakage. While Python 3.0 is not afraid to break backwards
compatibility, it tries to do so only when there's a very substantial
advantage. I guess enough people felt that having a shortcut for set()
was less important than keeping the current spelling of dict() the same.

There's even a sentiment in some pythonistas to get rid of the [] and {}
notations for lists and dicts, using list((1,2,3)) and dict((1,2),(3,4 ))
for [1,2,3] and {1:2, 3:4} respectively.

[Paul Rubin]

Re: builtin set literal

Paul Rubin <http://phr.cx@NOSPAM.i nvalidwrites:

notations for lists and dicts, using list((1,2,3)) and dict((1,2),(3,4 ))
for [1,2,3] and {1:2, 3:4} respectively.

Actually that would be dict(((1,2), (3,4))), of course.

[Hendrik van Rooyen]

Re: builtin set literal

"Paul Rubin" <http://phr.cx@NOSPAM.i nvalidwrote:

Steven Bethard <steven.bethard @gmail.comwrite s:

Yes, a lot of people liked this approach, but it was rejected due to
gratuitous breakage. While Python 3.0 is not afraid to break backwards
compatibility, it tries to do so only when there's a very substantial
advantage. I guess enough people felt that having a shortcut for set()
was less important than keeping the current spelling of dict() the same.

>
There's even a sentiment in some pythonistas to get rid of the [] and {}
notations for lists and dicts, using list((1,2,3)) and dict((1,2),(3,4 ))
for [1,2,3] and {1:2, 3:4} respectively.

YUK!

Moving in the wrong direction to bracketmania!

If you are going to use only one kind of brackets, use [] - on most keyboards,
you don't have to press the shift key - think of the numberless hours of total
time
saved by this simple reform...

It will also give Python a very distinctive "look" - unlike any other language.

- Hendrik