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>

doc/guix.texi

@@ -28188,7 +28188,7 @@ to maintain communication between devices on such network even when the
 connection to the Internet has been lost.  When left unspecified,
 the value from the account archive prevails.
 
-@item @code{bootstrap-hostnames} (type: maybe-string-list)
+@item @code{bootstrap-hostnames} (type: 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.
@@ -34509,7 +34509,7 @@ The group to run mpd as.
 
 The default @code{%mpd-group} is a system group with name ``mpd''.
 
-@item @code{shepherd-requirement} (default: @code{'()}) (type: list-of-symbol)
+@item @code{shepherd-requirement} (default: @code{'()}) (type: list-of-symbols)
 A list of symbols naming Shepherd services that this service
 will depend on.
 
@@ -34759,7 +34759,7 @@ Available @code{mympd-configuration} fields are:
 @item @code{package} (default: @code{mympd}) (type: file-like)
 The package object of the myMPD server.
 
-@item @code{shepherd-requirement} (default: @code{'()}) (type: list-of-symbol)
+@item @code{shepherd-requirement} (default: @code{'()}) (type: list-of-symbols)
 This is a list of symbols naming Shepherd services that this service
 will depend on.
 

gnu/services/audio.scm

@@ -138,9 +138,6 @@ (define (uglify-field-name field-name)
                                    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 @@ (define-configuration mpd-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 @@ (define-configuration/no-serialization mympd-configuration
     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)

gnu/services/configuration.scm

@@ -80,7 +80,9 @@ (define-module (gnu services configuration)
             interpose
             list-of
 
+            list-of-packages?
             list-of-strings?
+            list-of-symbols?
             alist?
             serialize-file-like
             text-config?
@@ -500,6 +502,11 @@ (define* (interpose ls  #:optional (delimiter "\n") (grammar 'infix))
                           (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 @@ (define (list-of pred?)
           (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?))
 

gnu/services/telephony.scm

@@ -117,15 +117,10 @@ (define (string-or-computed-file? val)
   (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 @@ (define-maybe string)
 
 ;;; 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 @@ (define-configuration jami-account
 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 @@ (define jami-account-transducer
 
   (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)