[bug#37322] [PATCH 1/2] adds the capability of importing a specified version to the crate importer

[Martin Becze <mjbecze@riseup.net>]

yep! thats the idea. I'll fix up the guile soon.

On 9/8/19 2:27 PM, Ludovic Courtès wrote:
> Hello Martin,
>
> So the goal is to allow users to run “guix import rust-foo@1.2.3”,
> right?  That’s a good idea.
>
> Martin Becze <mjbecze@riseup.net> skribis:
>
>> diff --git a/guix/import/crate.scm b/guix/import/crate.scm
>> index f6057dbf8b..3266ebdfec 100644
>> --- a/guix/import/crate.scm
>> +++ b/guix/import/crate.scm
>> @@ -1,6 +1,7 @@
>>  ;;; GNU Guix --- Functional package management for GNU
>>  ;;; Copyright © 2016 David Craven <david@craven.ch>
>>  ;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
>> +;;; Copyright © 2019 Martin Becze <mjbecze@riseup.net>
>>  ;;;
>>  ;;; This file is part of GNU Guix.
>>  ;;;
>> @@ -181,8 +182,8 @@ and LICENSE."
>>    ;; This regexp matches that.
>>    (make-regexp "^(.*) OR (.*)$"))
>>  
>> -(define (crate->guix-package crate-name)
>> -  "Fetch the metadata for CRATE-NAME from crates.io, and return the
>> +(define (crate->guix-package crate-name@version)
>> +  "Fetch the metadata for CRATE-NAME@VERSION from crates.io, and return the
> The idea is that the (guix import …) modules do not contain UI-related
> stuff, and that UI-related stuff is instead isolated in (guix scripts
> import …).
>
> Thus, splitting the “crate@version” string should happen in (guix
> scripts import crate) rather than in this module.
>
> Instead, you could simply change ‘crate->guix-package’ so that it takes
> an optional ‘version’ field:
>
>   (define* (crate->guix-package crate-name #:optional version)
>     …)
>
> In a second step, you’d change (guix scripts import crate) so that it
> passes that version string to ‘crate->guix-package’.
>
> How does that sound?
>
>> +  (define crate-name-version-list
>> +    (let ((lnv (string-split crate-name@version #\@)))
>> +      (if (= 1 (length lnv))
>> +	  (append lnv '(#f))
>> +	  lnv)))
>> +
>> +  (define crate-name
>> +    (car crate-name-version-list))
>> +
>> +
>>    (define crate
>>      (lookup-crate crate-name))
>>  
>> +  (define crate-version-string
>> +    (let ((version (cadr crate-name-version-list)))
>> +      (if version
>> +        version
>> +        (crate-latest-version crate))))
> We have a policy of not using ‘cadr’ and friends:
>
>   https://guix.gnu.org/manual/en/html_node/Data-Types-and-Pattern-Matching.html
>
> So the code above would typically look like:
>
>   (define-values (name version)
>     (match (string-split crate-spec #\@)
>       ((name version) (values name version))
>       ((name)         (values name #f))))
>
> Could you send an updated patch (actually two patches)?
>
> Thanks for working on the importer!
>
> Ludo’.