Re: [PATCH] profiles: Add gtk-icon-themes hook.

[Ludovic Courtès]

宋文武 <address@hidden> skribis:

> * guix/profiles.scm (gtk-icon-themes): New function.
>   (%default-profile-hooks): Add it.

[...]

> +(define (gtk-icon-themes manifest)
> +  "Return a derivation that unions all icon themes from manifest entries and
> +creates the GTK+ 'icon-theme.cache' file for each icon theme."
> +  (define (entry-lookup-gtk+ store entry)
> +    "Return the GTK+ package or store path referenced by the manifest ENTRY, 
> or
> +#f if not referenced."

Please use a comment rather than a docstring for inner defines.

> +    ;; Find GTK+ in a list of packages.
> +    (define (by-packages packages)
> +      (find (lambda (package)
> +              (equal? "gtk+" (package-name package)))
> +            packages))
> +
> +    ;; Find GTK+ in a list of store paths.
> +    (define (by-paths paths)
> +      (find (lambda (path)
> +              (equal? "gtk+"
> +                      (package-name->name+version
> +                       (store-path-package-name path))))
> +            paths))
> +
> +    (match (manifest-entry-item entry)
> +      ((? package? package)
> +       (by-packages (delete-duplicates
> +                     (map cadr (package-transitive-inputs package)))))
> +      ((? string? path)
> +       (by-paths (references store path)))))

This procedure must be turned into a monadic procedure along these
lines (note: by-packages -> find-among-packages, and by-paths ->
find-among-store-items):

  (define (lookup-gtk+ entry)
    (define (find-among-packages ...) ...)
    (define (find-among-store-items ...) ...)

    (with-monad %store-monad
      (match (manifest-entry-item entry)
        ((? package? package)
         (match (package-transitive-inputs package)
           (((labels packages . _) ...)
            (return (find-among-packages packages)))))
        ((? string? item)
         (mlet %store-monad ((refs (references* item)))
           (return (find-among-store-items refs)))))))

> +  (define (manifest-lookup-gtk+ store manifest)
> +    "Return the first GTK+ package or store path referenced by MANIFEST 
> entries,
> +or #f if not referenced by any entry."
> +    (any (cut entry-lookup-gtk+ store <>) (manifest-entries manifest)))

This becomes:

  (anym %store-monad
        (cut entry-lookup-gtk+ store <>)
        (manifest-entries manifest))

> +  (define gtk+
> +    (with-store store
> +      (manifest-lookup-gtk+ store manifest)))

Opening an extra connection like this is Very Bad.  ;-)
This is addressed by the above.

So this becomes:


  (mlet %store-monad ((gtk+ (lookup-gtk+ manifest)))
    (define build
      #~(...))

    ...)

Could you send an updated patch?

Thank you!

Ludo’.