Should we deprecate comma?

[w0rp]

On Monday, 24 March 2014 at 12:39:53 UTC, Marc Schütz wrote:
> On Monday, 24 March 2014 at 12:25:58 UTC, w0rp wrote:
>> Please kill the comma operator with fire. Is is just bad.
>>
>> On Monday, 24 March 2014 at 12:20:11 UTC, Marc Schütz wrote:
>>> Or, if you really want to distinguish them, this would work:
>>>
>>> (1,2)    two-element tuple
>>> (1,)     one-element tuple
>>> (1)      simple expression
>>> (,)      empty tuple
>>
>> I am a regular Python user, and I advise against using this 
>> syntax for tuples. I have been bitten many times by something 
>> which I thought was a tuple becoming an expression and 
>> something I thought was a simple expression becoming a tuple. 
>> It may be less of an issue in a static language, but it will 
>> still be an issue. I don't have an alternative syntax to 
>> propose.
>
> I'm not familiar with Python. What is the difference between a 
> one-element tuple and an expression? Are Python tuples just 
> arrays?

Consider the following.

>>> (1, 2)

(1, 2)

>>> (1)

1

>>> (1 * (3 * 4,))

(-1, )

>>> (1 * (3 - 4,) * 2)

(-1, -1)

>>> foo = lambda : 3

>>> (
...     foo()
... )

3

>>> (
...     foo(),
... )

(3, )

I see this kind of confusion happen often, and the convenient 
syntax becomes a burden.