Re: Using a function as build-step?

[Ludovic Courtès]

Hi!

Hartmut Goebel <address@hidden> skribis:

> while packaging some java apache common packages, I found myself adding
> some build steps over and over again, like this one:
>
>          (replace 'install
>            (lambda* (#:key outputs #:allow-other-keys)
>              (let ((share (string-append (assoc-ref outputs "out")
>                                          "/share/java")))
>                (for-each (λ (f) (install-file f share))
>                          (find-files "target" "\\.jar$")))))
>
> Now I tried replacing this by a simple line like
>
>          (add-after 'install 'install-javadocs install-javadocs)
>
> and of course some function:
>
>   (define* (install-javadoc #:key outputs #:allow-other-keys)
>     (let ((docs (string-append (assoc-ref outputs "doc")
>                                "/share/doc/" ,name "-" ,version "/")))
>       (mkdir-p docs)
>       (copy-recursively "target/apidocs" docs)
>       ))

Note that the commas here (aka. “unquote”) mean that this expression
must be enclosed in a ` (aka. “quasiquote”).  See
<https://www.gnu.org/software/guile/manual/html_node/Expression-Syntax.html#Expression-Syntax>.

> I did not manage this - not even if not using "name" and "version" and
> not using any function parameters.
>
> What is the correct code?

Like David, I would suggest creating a build-side module, say, (guix
build java-utils), or maybe augmenting (guix build ant-build-system),
and putting ‘install-javadoc’ in there (Ricardo?).

The code in there will not be in a quasiquote context, so you won’t be
able to use “,name” and “,version” to get at the package name and
version.

Instead, you could use ‘package-name->name+version’ from (guix build
utils):

  (define* (install-javadoc #:key outputs …)
    (let ((out (assoc-ref outputs "out")))
      (call-with-values
          (lambda ()
            (package-name->name+version (strip-store-file-name out)))
        (lambda (name version)
          …))))

HTH!

Ludo’.