Re: A friendlier API for operating-system declarations

[Liliana Marie Prikler <liliana.prikler@gmail.com>]

Am Sonntag, dem 25.02.2024 um 10:49 -0800 schrieb antlers:
> 
> 1.) It leaks `(guix records)`'s thunked/delayed field abstraction to
> the end-user, which will confuse and regularly bite absolutely anyone
> who tries to use it.
> 
> 2.) Ideally we'd check that modified fields exist at compile-time.
> This could require users to provide the record-type, which is not
> always public, but could also be optional.
You can get the record type of a record at run-time, so at least you
can synthesize a check that gives you a helpful message if that's what
you're gunning for.

> 3) The `cut`-like transformation is recursive and, while it has
> well-defined and tested behavior, the semantics are non-standard. I
> don't believe that the syntax achieves its goals without this
> mechanism, but there are remaining sub-concerns to address before I'd
> consider it ready to formalize and document.
Perhaps we can make it like modify-services where we take a value
updater instead of evaluating the forms directly?  This would fix both
#3 and #1 (since we'd unwrap the thunked/delayed field silently).
That would also make it so that we can use a single set of arrows (=>)
for both.

> 4) The syntax expands modifications of multiple fields into recursive
> expansions (ie: calls to the record constructor) when it would be
> more efficient (especially for thunked/delayed fields) to accumulate
> transformations by target field and `compose' them over a single call
> to the record constructor. This hasn't been an issue in practice, but
> would be the "right thing to do".
That's a minor detail, but it might be a syntax-rules → syntax-case
change.

> If I do raise the possibility of up-streaming it would be with these
> issues addressed, and would still have substantial cause to warrant
> discretionary discussion then. Really a scratching-my-own-itch
> solution atm.
Of course it'd go through the proper review channels first, but from
personal experience talk over at guix-devel is less likely to cause the
change you want over submitting an actual patch :)

Cheers