Re: Indentation with inline comments in Emacs

[Zelphir Kaltstahl]

Hello Taylan!

On 4/17/22 05:03, Taylan Kammer wrote:
> On 16.04.2022 14:12, Zelphir Kaltstahl wrote:
> > Hello Guile users!
> >
> > The subject might not be only Guile related, but I figure, that many on this 
> > mailing list are using Emacs for writing Guile code. I wonder, if anyone has 
> > some trick for fixing the following indentation issue:
> >
> > Sometimes I want to put inline comments with #||# in things like lists, 
> > arguments for function calls or vectors. For example I want to write the name 
> > of the month next to the number of days of that month, in a vector creation. 
> > Here is the example:
> >
> > ~~~~
> > (define DAYS-IN-MONTH
> >    #(#|January|# 31
> >                  #|February|# 28
> >                               #|March|# 31 #|April|# 30 #|May|# 31 #|June|# 30 
> > #|July|# 31 #|August|# 30
> >                                30 30))
> > ~~~~
> >
> > As you can see, the indentation is adjusted each line according to the non-comment thing 
> > on the previous line, when I press TAB or whatever other key binding one has for 
> > indentation. However, in this case I would rather want it to adjust indentation. Is there 
> > a quick fix for this? Or some way to make Emacs understand this as a separate case and 
> > have it indent "correctly"? Does anyone have a solution?
> >
> > Regards,
> > Zelphir
> To be honest, the easiest thing to do here is probably use a different comment 
> style.
>
> In this particular example I would probably just go full vertical:
>
>    (define DAYS-IN-MONTH
>      #(31 ;january
>        28 ;february
>        31 ;march
>        30 ;april
>        31 ;may
>        ;; ...
>      )
>
> I know it doesn't fulfill your requirement, but usually I find it wise to use 
> the
> "path of least resistance" when it comes to how an editor/IDE wants to format 
> code
> and just go with the rules it has.  Makes life easier for others who might not 
> have
> whatever custom configuration you add to your editor to bend it to your will.
Good point! For some reason I always shun the single semi-colon comments. I 
think that is, because I usually start writing such a comment and then notice, 
that the comment will make the line very long, so I want to break it. However, 
to break it, it makes more sense to have the comment above the line and use 
double semi-colon. In this case however, the single semi-colon does actually 
seem like a good alternative.
> Tangential:
>
> I've also tried out a "columns" variant with multiple numbers per row and a 
> comment
> above each row identifying the numbers, but Emacs seems to insist on 
> special-casing
> the first column in that case, regardless of comments, like this:
>
>    (define days
>      #(31      28       31
>                30       31          30
>                xx       yy          zz
>                ;; ...
>                ))
>
> That's already ugly without comments, and IMO a significant issue.
>
> Maybe it would be good to teach Emacs to indent lists/vectors that don't 
> represent
> a function/macro call.  This indentation clearly assumes that the leading "31" 
> in
> the vector is the operator, and the rest of the vector operands.
>
> It should probably not assume that for vectors #(...) and quoted lists '(...).

I never understood, why Emacs indented that way, but now I understand. First 
argument is seen as special, as the function/procedure that is being called – 
aha! I do not know, whether the syntax for vector creation #(...) is the same in 
all Scheme dialects, which have vectors, in general. Perhaps it would require a 
specific GNU Guile mode for Emacs, if it is not the same in all Scheme dialects.

Best regards,
Zelphir

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