Yes the same consideration applies to any new feature. I think that
Python's reticence to add new features has been a strength. And I do think
the benefit here is absolutely negligible.

It's not that I don't like constants - but there's a bunch of things that
go great together, like constants, functional programming, and static type
analysis, and none of those are in python. There are plenty of languages
that have that; and nothing that prevents you from creating a desugaring
compiler for an extended version of python. Indeed, I think that a lot of
features like annotations would be better in an extension project.

Constants (from a code quality perspective) really manifest their benefits
in statically preventing errors. A linter can warn about assignment to
ALL_CAPS, ClassNames, and built-in names. If you're following appropriate
conventions (and your linter isn't a pure peephole linter) you can identify
those errors.

On Fri, Nov 17, 2017 at 4:47 PM, Saeed Baig <> wrote:

> Well I think that depends on how one defines simplicity. Which seems
> simpler, this:
> # Treat as constants
> c = 299792458 # Speed of light
> e = 2.71828 # Euler’s constant
> or this:
> let c = 299792458 # Speed of light
> let e = 2.71828 # Euler’s constant
> The latter involves less typing, and is hardly more difficult to
> understand.
> I can see where you’re coming from; it does arguably add complexity. But
> one could argue that ANY new feature to the language (list comprehension,
> lambdas, type hints, etc) will add complexity to the language just by
> virtue of being an extra thing to learn. One has to consider the benefit VS
> cost of a new feature by comparing “How useful is it” to “How complex is
> it”.
> And forgive me for my ignorance on this topic, but how can linting give
> the benefits of constants?
> On 18 Nov 2017, at 02:14, Marcin Tustin <> wrote:
> I'm against this because Python's strength is its simplicity. This doesn't
> actually simplify anything, but it does add a new language feature to
> understand.
> All the benefits of this can be achieved with linting.
> On Thu, Nov 16, 2017 at 1:16 AM, Saeed Baig <>
> wrote:
>> Hey guys I am thinking of perhaps writing a PEP to introduce constants to
>> Python. Something along the lines of Swift’s “let” syntax (e.g. “let pi =
>> 3.14”).
>> Since I’m sort of new to this, I just wanted to ask:
>> - Has a PEP for this already been written? If so, where can I find the
>> link/info to it?
>> - Do you guys think it would be a good idea? Why or why not? Do you think
>> there’s a better way to do it? I’d like to know what others think about
>> this idea before making any formal submission.
>> --
> --
> Marcin Tustin
> Tel: +1 917 553 3974 <(917)%20553-3974>

Marcin Tustin
Tel: +1 917 553 3974

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