[bug#35684] import: github: Sort releases before picking the latest one.

[Ludovic Courtès]

Arun Isaac <address@hidden> skribis:

> Prior to this, for some packages (e.g., osc in (gnu packages
> build-tools)), `guix refresh' could not find the latest version
> correctly.

Good catch.

> From 33f42ea8a33c6e502062708336a5ab8be871c92b Mon Sep 17 00:00:00 2001
> From: Arun Isaac <address@hidden>
> Date: Sat, 11 May 2019 16:40:38 +0530
> Subject: [PATCH] import: github: Sort releases before picking the latest one.
>
> * guix/import/github.scm (latest-released-version): Sort releases before
> picking the first one as the latest.

[...]

> +        (first
> +         (sort
> +          (filter-map
> +           (lambda (release)
> +             (let ((tag (or (hash-ref release "tag_name") ;a "release"
> +                            (hash-ref release "name")))   ;a tag
> +                   (name-length (string-length package-name)))
> +               (cond
> +                ;; some tags include the name of the package e.g. 
> "fdupes-1.51"
> +                ;; so remove these
> +                ((and (< name-length (string-length tag))
> +                      (string=? (string-append package-name "-")
> +                                (substring tag 0 (+ name-length 1))))
> +                 (substring tag (+ name-length 1)))
> +                ;; some tags start with a "v" e.g. "v0.25.0"
> +                ;; where some are just the version number
> +                ((string-prefix? "v" tag)
> +                 (substring tag 1))
> +                ;; Finally, reject tags that don't start with a digit:
> +                ;; they may not represent a release.
> +                ((and (not (string-null? tag))
> +                      (char-set-contains? char-set:digit
> +                                          (string-ref tag 0)))
> +                 tag)
> +                (else #f))))
> +           (match (remove pre-release? json)
> +             (() json) ; keep everything
> +             (releases releases)))
> +          version>?)))))

LGTM, but…

… while you’re at it, would you mind cleaning this up a bit?  :-)
Namely, I think this big ‘lambda’ could be given a name and moved out of
the way to make ‘latest-released-version’ easier to read.  Also, it
would probably be reasonable to avoid ‘first’ and instead write:

  (match (sort …)
    ((first . _) first)
    (()
     (leave (G_ "no releases found etc.~%"))))

WDYT?  :-)

If you’d rather leave that for later, you can also just go ahead and
commit your patch.

Thanks,
Ludo’.