services: replace bare serializers with (serializer ...)

* gnu/home/services/shells.scm
(home-zsh-configuration)[environment-variables]: Use (serializer ...).
(home-bash-configuration)[aliases, environment-variables]: Likewise.
(home-fish-configuration)[abbreviations, aliases]
[environment-variables]: Likewise.
* gnu/services/audio.scm (mpd-configuration)[music-dir, playlist-dir]
[endpoints, address, inputs, archive-plugins, input-cache-size]
[decoders, filters, playlist-plugins]: Likewise.
* gnu/services/linux.scm (fstrim-configuration)[extra-arguments]:
Likewise.
* gnu/services/security.scm (fail2ban-jail-configuration)[backend]
[log-encoding, extra-content]: Likewise.
* tests/services/configuration.scm: Update tests.
("serialize-configuration [deprecated]"): New test.

Signed-off-by: Liliana Marie Prikler <liliana.prikler@gmail.com>

gnu/home/services/shells.scm

@@ -133,7 +133,7 @@ (define-configuration home-zsh-configuration
   (environment-variables
    (alist '())
    "Association list of environment variables to set for the Zsh session."
-   serialize-posix-env-vars)
+   (serializer serialize-posix-env-vars))
   (zshenv
    (text-config '())
    "List of file-like objects, which will be added to @file{.zshenv}.
@@ -334,7 +334,7 @@ (define-configuration home-bash-configuration
 rules for the @code{home-environment-variables-service-type} apply
 here (@pxref{Essential Home Services}).  The contents of this field will be
 added after the contents of the @code{bash-profile} field."
-   serialize-posix-env-vars)
+   (serializer serialize-posix-env-vars))
   (aliases
    (alist '())
    "Association list of aliases to set for the Bash session.  The aliases will be
@@ -351,7 +351,7 @@ (define-configuration home-bash-configuration
 @example
 alias ls=\"ls -alF\"
 @end example"
-   bash-serialize-aliases)
+   (serializer bash-serialize-aliases))
   (bash-profile
    (text-config '())
    "List of file-like objects, which will be added to @file{.bash_profile}.
@@ -536,19 +536,19 @@ (define-configuration home-fish-configuration
   (environment-variables
    (alist '())
    "Association list of environment variables to set in Fish."
-   serialize-fish-env-vars)
+   (serializer serialize-fish-env-vars))
   (aliases
    (alist '())
    "Association list of aliases for Fish, both the key and the value
 should be a string.  An alias is just a simple function that wraps a
 command, If you want something more akin to @dfn{aliases} in POSIX
 shells, see the @code{abbreviations} field."
-   serialize-fish-aliases)
+   (serializer serialize-fish-aliases))
   (abbreviations
    (alist '())
    "Association list of abbreviations for Fish.  These are words that,
 when typed in the shell, will automatically expand to the full text."
-   serialize-fish-abbreviations))
+   (serializer serialize-fish-abbreviations)))
 
 (define (fish-files-service config)
   `(("fish/config.fish"

gnu/services/audio.scm

@@ -370,7 +370,7 @@ (define-configuration mpd-configuration
   (music-dir ; TODO: deprecated, remove later
    maybe-string
    "The directory to scan for music files."
-   mpd-serialize-deprecated-field)
+   (serializer mpd-serialize-deprecated-field))
 
   (playlist-directory
    maybe-string
@@ -379,7 +379,7 @@ (define-configuration mpd-configuration
   (playlist-dir ; TODO: deprecated, remove later
    maybe-string
    "The directory to store playlists."
-   mpd-serialize-deprecated-field)
+   (serializer mpd-serialize-deprecated-field))
 
   (db-file
    maybe-string
@@ -405,16 +405,17 @@ (define-configuration mpd-configuration
 port is used.
 To use a Unix domain socket, an absolute path or a path starting with @code{~}
 can be specified here."
+   (serializer
     (lambda (_ endpoints)
       (if (maybe-value-set? endpoints)
           (mpd-serialize-list-of-strings "bind_to_address" endpoints)
-         "")))
+          ""))))
 
   (address ; TODO: deprecated, remove later
    maybe-string
    "The address that mpd will bind to.
 To use a Unix domain socket, an absolute path can be specified here."
-   mpd-serialize-deprecated-field)
+   (serializer mpd-serialize-deprecated-field))
 
   (database
    maybe-mpd-plugin
@@ -431,29 +432,29 @@ (define-configuration mpd-configuration
   (inputs
    (list-of-mpd-plugin '())
    "List of MPD input plugin configurations."
-   (lambda (_ x)
-     (mpd-serialize-list-of-mpd-plugin "input" x)))
+   (serializer (lambda (_ x)
+                 (mpd-serialize-list-of-mpd-plugin "input" x))))
 
   (archive-plugins
    (list-of-mpd-plugin '())
    "List of MPD archive plugin configurations."
-   (lambda (_ x)
-     (mpd-serialize-list-of-mpd-plugin "archive_plugin" x)))
+   (serializer (lambda (_ x)
+                 (mpd-serialize-list-of-mpd-plugin "archive_plugin" x))))
 
   (input-cache-size
    maybe-string
    "MPD input cache size."
-   (lambda (_ x)
+   (serializer (lambda (_ x)
                  (if (maybe-value-set? x)
                      #~(string-append "\ninput_cache {\n"
                                       #$(mpd-serialize-string "size" x)
-                          "}\n") "")))
+                                      "}\n") ""))))
 
   (decoders
    (list-of-mpd-plugin '())
    "List of MPD decoder plugin configurations."
-   (lambda (_ x)
-     (mpd-serialize-list-of-mpd-plugin "decoder" x)))
+   (serializer (lambda (_ x)
+                 (mpd-serialize-list-of-mpd-plugin "decoder" x))))
 
   (resampler
    maybe-mpd-plugin
@@ -462,8 +463,8 @@ (define-configuration mpd-configuration
   (filters
    (list-of-mpd-plugin '())
    "List of MPD filter plugin configurations."
-   (lambda (_ x)
-     (mpd-serialize-list-of-mpd-plugin "filter" x)))
+   (serializer (lambda (_ x)
+                 (mpd-serialize-list-of-mpd-plugin "filter" x))))
 
   (outputs
    (list-of-mpd-plugin-or-output (list (mpd-output)))
@@ -473,8 +474,8 @@ (define-configuration mpd-configuration
   (playlist-plugins
    (list-of-mpd-plugin '())
    "List of MPD playlist plugin configurations."
-   (lambda (_ x)
-     (mpd-serialize-list-of-mpd-plugin "playlist_plugin" x)))
+   (serializer (lambda (_ x)
+                 (mpd-serialize-list-of-mpd-plugin "playlist_plugin" x))))
 
   (extra-options
    (alist '())

gnu/services/linux.scm

@@ -213,9 +213,10 @@ (define-configuration fstrim-configuration
    maybe-list-of-strings
    "Extra options to append to @command{fstrim} (run @samp{man fstrim} for
 more information)."
+   (serializer
     (lambda (_ value)
       (if (maybe-value-set? value)
-         value '())))
+          value '()))))
   (prefix fstrim-))
 
 (define (serialize-fstrim-configuration config)

gnu/services/security.scm

@@ -200,7 +200,7 @@ (define-configuration fail2ban-jail-configuration
    "Backend to use to detect changes in the @code{log-path}.  The default is
 'auto.  To consult the defaults of the jail configuration, refer to the
 @file{/etc/fail2ban/jail.conf} file of the @code{fail2ban} package."
-   fail2ban-jail-configuration-serialize-backend)
+   (serializer fail2ban-jail-configuration-serialize-backend))
   (max-retry
    maybe-integer
    "The number of failures before a host get banned
@@ -269,7 +269,7 @@ (define-configuration fail2ban-jail-configuration
    maybe-symbol
    "The encoding of the log files handled by the jail.
 Possible values are: @code{'ascii}, @code{'utf-8} and @code{'auto}."
-   fail2ban-jail-configuration-serialize-log-encoding)
+   (serializer fail2ban-jail-configuration-serialize-log-encoding))
   (log-path
    (list-of-strings '())
    "The file names of the log files to be monitored.")
@@ -280,7 +280,7 @@ (define-configuration fail2ban-jail-configuration
    (text-config '())
    "Extra content for the jail configuration, provided as a list of file-like
 objects."
-   serialize-text-config)
+   (serializer serialize-text-config))
   (prefix fail2ban-jail-configuration-))
 
 (define list-of-fail2ban-jail-configurations?

tests/services/configuration.scm

@@ -82,6 +82,9 @@ (define (custom-number-serializer name value)
   (format #f "~a = ~a;" name value))
 
 (define-configuration serializable-configuration
+  (port (number 80) "The port number." (serializer custom-number-serializer)))
+
+(define-configuration serializable-configuration-deprecated
   (port (number 80) "The port number." custom-number-serializer))
 
 (test-assert "serialize-configuration"
@@ -89,8 +92,14 @@ (define-configuration serializable-configuration
    (let ((config (serializable-configuration)))
      (serialize-configuration config serializable-configuration-fields))))
 
+(test-assert "serialize-configuration [deprecated]"
+  (gexp?
+   (let ((config (serializable-configuration-deprecated)))
+     (serialize-configuration
+      config serializable-configuration-deprecated-fields))))
+
 (define-configuration serializable-configuration
-  (port (number 80) "The port number." custom-number-serializer)
+  (port (number 80) "The port number." (serializer custom-number-serializer))
   (no-serialization))
 
 (test-assert "serialize-configuration with no-serialization"