Subject: [bug#69052] [PATCH v2] gnu: guix: Correct home-channels-service-type extension logic.

From: Ludovic Courtès <[email-masked]>
Date: Sat, 02 Mar 2024 16:19:51 +0100

Hi,

Nicolas Graves <[email-masked]> skribis:

> * gnu/home/services/guix.scm
> (extend-channel-list): Add function.
> (home-channels-service-type)[extend]: Use extend-channel-list.
>
> Change-Id: I587207b86216f075a54b6ed0b8fa998896bbed74

[...]

> +(define (channel-name-symbol channel)
> +  (match (channel-name channel)
> +    ((? symbol? name) name)
> +    ((? string? name) (string->symbol name))))

‘channel-name’ always returns a symbol so this procedure can be removed.

> +(define (extend-channel-list default new)
> +  "Prepend the channels in NEW by the channels in DEFAULT if their
> +channel-name is not in NEW."
> +  (fold-right
> +   (lambda (channel acc)
> +     (if (member (channel-name channel) (map channel-name-symbol acc))
> +         acc
> +         (cons channel acc)))
> +   new default))

[...]

> +   (extend extend-channel-list)

I believe it’s equivalent to:

  (define (extend-channel-list initial new)
    (delete-duplicates
     (append initial new)
     (lambda (channel1 channel2)
       (eq? (channel-name channel1) (channel-name channel2)))))

… which is somewhat clearer IMO.

Could you send an updated patch?

Ludo’.