Re: [GSOC][PATCH] userdiff: add support for Scheme

[Phillip Wood <phillip.wood123@gmail.com>]

Hi Atharva

On 28/03/2021 13:40, Atharva Raykar wrote:
> On 28-Mar-2021, at 08:46, Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
>> The "define-?.*" can be simplified to just "define.*", but looking at
>> the tests is that the intent? From the tests it looks like "define[- ]"
>> is what the author wants, unless this is meant to also match
>> "(definements".
> 
> Yes, you captured my intent correctly. Will fix it.
> 
>> Has this been tested on some real-world scheme code? E.g. I have guile
>> installed locally, and it has really large top-level eval-when
>> blocks. These rules would jump over those to whatever the function above
>> them is.
> 
> I do not have a large scheme codebase on my own, I usually use Racket,
> which is a much larger language with many more forms. Other Schemes like
> Guile also extend the language a lot, like in your example, eval-when is
> an extension provided by Guile (and Chicken and Chez), but not a part of
> the R6RS document when I searched its index.
> 
> So the 'define' forms are the only one that I know would reliably be present
> across all schemes. But one can also make a case where some of these non-standard
> forms may be common enough that they are worth adding in. In that case which
> forms to include? Should we consider everything in the SRFI's[1]? Should the
> various module definitions of Racket be included? It's a little tricky to know
> where to stop.

If there are some common forms such as eval-when then it would be good 
to include them, otherwise we end up needing a different rule for each 
scheme implementation as they all seem to tweak something. Gerbil uses 
'def...' e.g def, defsyntax, defstruct, defrules rather than define, 
define-syntax, define-record etc. I'm not user if we want to accommodate 
that or not.

Best Wishes

Phillip


> That being said, I will try to run this through more Scheme codebases that I can
> find and see if there are any forms that seem to show up commonly enough that they
> are worth including.
> 
> [1] https://en.wikipedia.org/wiki/Scheme_Requests_for_Implementation
>