Subject: Re: Coding style: similarly-named variables

From: Ludovic Courtès <[email-masked]>
Date: Sun, 20 Nov 2022 11:46:00 +0100

Hi,

Maxim Cournoyer <[email-masked]> skribis:

[...]

>>> It's a pattern I've used at other places; I find it more hygienic to not
>>> shadow existing variables; it signal to the reader "be careful, this is
>>> not the same as the argument-bound one, though they are closely
>>> related".
>>
>> I don’t buy it.  :-)  The reader might be careful yet end up using the
>> “wrong” variable.  As long as the “wrong” variable has no use, I think
>> it’s best to shadow it so that mistakes cannot happen.
>
> I'm surprised you're not buying it, given we're writing Scheme in a more
> functional style, and mutating same-named variables clearly goes against
> that style :-).

There’s no mutation here, only lexical scoping.  Anyway, I find it clear
that the risk of typing ‘x’ instead of ‘x*’, especially in relatively
long functions, justifies shadowing in situations like this one.  WDYT?

>> Of course the details vary depending on context, but I think we should
>> not start introducing this pattern in different places.  Perhaps
>> something to discuss and codify under “Formatting Code”?
>
> That's more of a coding style guidelines than "formatting" code

Sorry I meant “Coding Style”, which is the section that documents the
project’s conventions.

> (when I read "formatting", I think of a mechanical process like 'guix
> style' or 'rust-fmt' can do), but yes, that could be nice to have.
> Better yet, something basic to share across the whole Guile/Scheme
> community and include in the Guile user manual, like Python has PEP 8
> they can refer to, to save every Guile/Scheme project from having to
> reinvent the wheel.

I won’t do it, but sure, why not!  My immediate concern is to make sure
we have a shared understanding, within Guix, of some of the conventions
we follow.  It’s a minor issue, but minor issues are what our day-to-day
work is made of.  :-)

Thanks,
Ludo’.