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

From: Ludovic Courtès <[email-masked]>
Date: Sun, 08 Sep 2019 14:27:48 +0200

Hello Martin,

So the goal is to allow users to run “guix import [email-masked]”,
right?  That’s a good idea.

Martin Becze <[email-masked]> 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 <[email-masked]>
>  ;;; Copyright © 2019 Ludovic Courtès <[email-masked]>
> +;;; Copyright © 2019 Martin Becze <[email-masked]>
>  ;;;
>  ;;; 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’.