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>

3 files changed, 26 insertions, 18 deletions

diff --git a/gnu/services/audio.scm b/gnu/services/audio.scm
index 260abdefed1..ae991ced4d6 100644
--- a/gnu/services/audio.scm
+++ b/gnu/services/audio.scm
@@ -138,9 +138,6 @@
                                    str)
                                #\-) "_")))
 
-(define list-of-symbol?
-  (list-of symbol?))
-
 ;; Helpers for deprecated field types, to be removed later.
 (define %lazy-group (make-symbol "%lazy-group"))
 
@@ -428,7 +425,7 @@ to be appended to the audio output configuration.")
    (sanitizer mpd-group-sanitizer))
 
   (shepherd-requirement
-   (list-of-symbol '())
+   (list-of-symbols '())
    "This is a list of symbols naming Shepherd services that this service
 will depend on."
    empty-serializer)
@@ -763,7 +760,7 @@ user-group instead~%"))
     empty-serializer)
 
   (shepherd-requirement
-   (list-of-symbol '())
+   (list-of-symbols '())
    "This is a list of symbols naming Shepherd services that this service
 will depend on."
    empty-serializer)
diff --git a/gnu/services/configuration.scm b/gnu/services/configuration.scm
index aa5fb832d57..d2b1687496c 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?))
 
diff --git a/gnu/services/telephony.scm b/gnu/services/telephony.scm
index 56b7772f58e..c9b5d6cd994 100644
--- a/gnu/services/telephony.scm
+++ b/gnu/services/telephony.scm
@@ -117,15 +117,10 @@
   (or (string? val)
       (computed-file? val)))
 
-(define (string-list? val)
-  (and (list? val)
-       (and-map string? val)))
+(define account-fingerprint-list?
+  (list-of account-fingerprint?))
 
-(define (account-fingerprint-list? val)
-  (and (list? val)
-       (and-map account-fingerprint? val)))
-
-(define-maybe string-list)
+(define-maybe list-of-strings)
 
 (define-maybe/no-serialization account-fingerprint-list)
 
@@ -135,7 +130,7 @@
 
 ;;; The following serializers are used to derive an account details alist from
 ;;; a <jami-account> record.
-(define (serialize-string-list _ val)
+(define (serialize-list-of-strings _ val)
   (string-join val ";"))
 
 (define (serialize-boolean _ val)
@@ -188,7 +183,7 @@ maintain communication between devices on such network even when the
 connection to the the Internet has been lost.  When left unspecified, the
 value from the account archive prevails.")
   (bootstrap-hostnames
-   maybe-string-list
+   maybe-list-of-strings
    "A list of hostnames or IPs pointing to OpenDHT nodes, that should be used
 to initially join the OpenDHT network.  When left unspecified, the value from
 the account archive prevails.")
@@ -220,9 +215,8 @@ SET-ACCOUNT-DETAILS."
 
   (list-transduce jami-account-transducer rcons jami-account-fields))
 
-(define (jami-account-list? val)
-  (and (list? val)
-       (and-map jami-account? val)))
+(define jami-account-list?
+  (list-of jami-account?))
 
 (define-maybe/no-serialization jami-account-list)