On Tue, Jan 02, 2018 at 07:39:56PM +0100, Stefan Reichör wrote:
> * gnu/packages/music.scm (instantmusic): New variable.

Thanks for this patch Stefan! I have some comments...

> +      (version (string-append "0.1-" revision "." (string-take commit 9)))

I noticed the latest upstream release is tagged "v1.0" rather than
"0.1". Also, it's convenient and more maintainable to create the version
of Git-based packages like this:

(version (git-version "1.0" revision commit))

> +                (file-name (string-append name "-" version "-checkout"))

And similarly for the file-name:

(file-name (git-file-name name version))

Those two procedures come from (guix git-download).

> +    (arguments
> +     '(#:modules ((guix build python-build-system)
> +                  (guix build utils)
> +                  (srfi srfi-26))
> +       #:phases (modify-phases %standard-phases
> +                  (add-before 'build 'change-directory
> +                    (lambda _
> +                      (chdir "instantmusic-0.1")
> +                      ;; Fix some read-only files that would cause a build failure
> +                      (for-each (cut chmod <> #o644)
> +                                (find-files "instantmusic.egg-info"
> +                                            "PKG-INFO|.*\\.txt"))
> +                      #t)))))

I guess that changing the build directory and chmod-ing those files are
required for their own reasons, right? So they should be in separate
build phases.

Can you send an updated patch?