From: Ricardo Wurmus <rekado@elephly.net>
To: Olivier Dion <olivier.dion@polymtl.ca>
Cc: gwl-devel@gnu.org
Subject: Re: [PATCH v2 1/2] packages: Support for full Guix specification
Date: Tue, 26 Apr 2022 22:30:21 +0200 [thread overview]
Message-ID: <875ymv5z0l.fsf@elephly.net> (raw)
In-Reply-To: <875ymvhds4.fsf@laura>
Hi again,
Olivier Dion <olivier.dion@polymtl.ca> writes:
>>> + ((first . rest) first)
>>> + (_ (raise (condition
>>> + (&gwl-package-error
>>> + (package-spec (string-append name+version output)))))))
>>> + output))
>>
>> I’d prefer to have this return multiple values instead of a compound
>> value.
>
> With (values ...)? That's what (gnu packages) does I think.
I think I missed how you intended for this to work. IIUC you’re letting
LOOKUP-PACKAGE return a list of a package and an output because that
will end up as an argument to PACKAGES->MANIFEST (in (@ (gwl processes)
process->script)).
PACKAGES->MANIFEST has this docstring:
"Return a list of manifest entries, one for each item listed in PACKAGES.
Elements of PACKAGES can be either package objects or package/string tuples
denoting a specific output of a package."
So that’s why you’re making it return a tuple of package/string tuples –
for compatibility with that procedure.
My comment about returning multiple values or a record value totally
misses your intent. Sorry! Now I get it.
> I do think it would be better to wait for (guix inferior) to support
> selecting outputs. However, I do need selection of outputs for my use
> case right now! Specificaly, I need to have debug symbols of many
> packages. The quick hack above does the work for me but I understand
> that it would be preferable if (guix inferior) has support for outputs
> instead.
I understand.
So … I think we can figure something out that won’t be far removed from
what you proposed. I’d probably split it into smaller procedures,
though, to make it a bit more obvious what’s going on.
Let’s see the diff again…
> -(define (lookup-package specification)
> +(define (%lookup-package name+version output)
> + (list (match (apply lookup-inferior-packages
> + (cons (current-guix) (string-split name+version #\@)))
> + ((first . rest) first)
> + (_ (raise (condition
> + (&gwl-package-error
> + (package-spec (string-append name+version output)))))))
> + output))
>
> +(define* (lookup-package specification #:optional (output "out"))
> (log-event 'guix (G_ "Looking up package `~a'~%") specification)
> - (match (lookup-inferior-packages (current-guix) specification)
> - ((first . rest) first)
> - (_ (raise (condition
> - (&gwl-package-error
> - (package-spec specification)))))))
> + (match (string-split specification #\:)
> + ((name+version sub-drv) (%lookup-package name+version sub-drv))
> + ((name+version) (simple-package (%lookup-package name+version output)))))
I’m struggling to figure out a cleaner way to do this…
Why are we processing the specification *and* accept an optional OUTPUT
argument? It seems to me that SUB-DRV and OUTPUT *should* be the same,
but it’s possible to call LOOKUP-PACKAGE in a way that they differ,
which doesn’t make much sense to me.
Another thing that bothers me a bit is all that string splitting; once
for version, again for the output. The (guix ui) module has
PACKAGE-SPECIFICATION->NAME+VERSION+OUTPUT, which is dedicated for this
task. It returns multiple values; let’s use LET* from SRFI-71. What do
you think of this?
--8<---------------cut here---------------start------------->8---
(import (srfi srfi-71)
(define (lookup-package specification)
"Look up SPECIFICATION in an inferior and return a matching package. If the
specification declares a specific output return a tuple consisting of the
package value and the output. If no matching package is found, raise a
&GWL-PACKAGE-ERROR."
(log-event 'guix (G_ "Looking up package `~a'~%") specification)
(let* ((name version output (package-specification->name+version+output specification))
(package
(match (lookup-inferior-packages (current-guix) name version)
((first . rest) first)
(_ (raise (condition
(&gwl-package-error
(package-spec specification))))))))
(if output
(list package output)
package)))
--8<---------------cut here---------------end--------------->8---
What do you think of that?
> (define (valid-package? val)
> - (or (package? val)
> - (inferior-package? val)))
> + (or
> + (and (list? val)
> + (valid-package? (car val))
> + (string? (cadr val)))
> + (package? val)
> + (inferior-package? val)))
> +
I suggest rewriting this whole thing with MATCH so that the structure of
VAL becomes apparent. Perhaps something like this?
(match
((maybe-package (? string? output))
(valid-package? maybe-package))
(_
(or (package? val)
(inferior-package? val))))
> +(define (simple-package pkg)
> + (if (list? pkg) (car pkg) pkg))
I still don’t like this :) Not only the implementation but the fact
that it appears to be needed. At least implementation-wise I’d prefer
something like this:
(define (just-package maybe-package+output)
(match maybe-package+output
(((? package? package) (? string? output)) package)
((? package? package) package)
(_ (error "what is this?"))))
There are a few places where we need to be careful that we’re dealing
with the right type and that we handle both cases equally well: when a
tuple is encountered and when a plain package value is encountered.
Ideally we’d also have tests for this.
What do you think of all this?
--
Ricardo
next prev parent reply other threads:[~2022-04-26 21:14 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-21 17:22 Packages specification does not work Olivier Dion via
2022-04-21 18:25 ` Olivier Dion via
2022-04-21 19:51 ` [PATCH v1 1/2] packages: Support for full Guix specification Olivier Dion
2022-04-21 19:51 ` [PATCH v1 2/2] pre-inst-env.in: Export GUIX_EXTENSIONS_PATH Olivier Dion
2022-04-29 11:42 ` Ricardo Wurmus
2022-04-21 20:10 ` [PATCH v1 1/2] packages: Support for full Guix specification Olivier Dion via
2022-04-22 18:43 ` [PATCH v2 0/2] Support full package specifications Olivier Dion
2022-04-22 18:43 ` [PATCH v2 1/2] packages: Support for full Guix specification Olivier Dion
2022-04-26 18:11 ` Ricardo Wurmus
2022-04-26 18:59 ` Olivier Dion via
2022-04-26 20:30 ` Ricardo Wurmus [this message]
2022-04-26 21:52 ` Olivier Dion via
2022-04-22 18:43 ` [PATCH v2 2/2] pre-inst-env.in: Export GUIX_EXTENSIONS_PATH Olivier Dion
2022-04-29 9:00 ` zimoun
2022-04-29 18:02 ` [PATCH v3 0/1] Support full package specifications Olivier Dion
2022-04-29 18:02 ` [PATCH v3 1/1] packages: Support for full Guix specification Olivier Dion
2022-05-22 6:43 ` Ricardo Wurmus
2022-05-22 12:33 ` Olivier Dion via
2022-05-17 20:40 ` [PATCH v3 0/1] Support full package specifications Olivier Dion via
2022-05-22 12:38 ` [PATCH v4] packages: Support for full Guix specification Olivier Dion
2022-05-23 21:02 ` Ricardo Wurmus
2022-05-23 21:45 ` [PATCH v5] " Olivier Dion
2022-06-01 13:07 ` Ricardo Wurmus
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