services: configuration: Add some commonly used predicates.

* gnu/services/configuration.scm (list-of-packages?, list-of-symbols?): New
predicate.
* gnu/services/audio.scm (list-of-symbol?): Remove.
* gnu/services/telephony.scm (string-list?): Remove.
(serialize-string-list): Rename to …
(serialize-list-of-strings): … this.
(account-fingerprint-list?, jami-account-list?): Use list-of.
* doc/guix.texi: Update it.

Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/gnu/services/configuration.scm b/gnu/services/configuration.scm
index aa5fb832d5..d2b1687496 100644
--- a/gnu/services/configuration.scm
+++ b/gnu/services/configuration.scm
@@ -80,7 +80,9 @@
             interpose
             list-of
 
+            list-of-packages?
             list-of-strings?
+            list-of-symbols?
             alist?
             serialize-file-like
             text-config?
@@ -500,6 +502,11 @@ DELIMITER interposed LS.  Support 'infix and 'suffix GRAMMAR values."
                           (cons delimiter acc))))
               '() ls))
 
+
+;;;
+;;; Commonly used predicates
+;;;
+
 (define (list-of pred?)
   "Return a procedure that takes a list and check if all the elements of
 the list result in @code{#t} when applying PRED? on them."
@@ -508,10 +515,20 @@ the list result in @code{#t} when applying PRED? on them."
           (every pred? x)
           #f)))
 
+(define list-of-packages?
+  (list-of package?))
 
 (define list-of-strings?
   (list-of string?))
 
+(define list-of-symbols?
+  (list-of symbol?))
+
+
+;;;
+;;; Special serializers
+;;;
+
 (define alist?
   (list-of pair?))