services: messaging: Prosody config supports file-like objects.

* doc/guix.texi (Messaging Services): Update accordingly.
* gnu/services/configuration.scm (serialize-configuration,
serialize-maybe-stem, serialize-package): Return strings or string-valued
gexps (these procedures were only used for their side-effects).
* gnu/services/messaging.scm (serialize-field, serialize-field-list,
enclose-quotes, serialize-raw-content, serialize-ssl-configuration,
serialize-virtualhost-configuration-list,
serialize-int-component-configuration-list,
serialize-ext-component-configuration-list,
serialize-virtualhost-configuration, serialize-int-component-configuration,
serialize-ext-component-configuration, serialize-prosody-configuration):
Return strings or string-valued gexps and stop printing.
(prosody-activation): Use SERIALIZE-PROSODY-CONFIGURATION's return value with
MIXED-TEXT-FILE instead of using its output with PLAIN-FILE.
(serialize-non-negative-integer, serialize-non-negative-integer-list): Convert
numbers to strings.
(file-object?, serialize-file-object, file-object-list?,
serialize-file-object-list): New procedures.
(ssl-configuration)[capath, cafile], (prosody-configuration)[plugin-paths,
groups-file]: Replace FILE-NAME with FILE-OBJECT.
* guix/gexp.scm (file-like?): New exported procedure.

1 files changed, 9 insertions, 8 deletions

diff --git a/gnu/services/configuration.scm b/gnu/services/configuration.scm
index c45340f02f..707944cbe0 100644
--- a/gnu/services/configuration.scm
+++ b/gnu/services/configuration.scm
@@ -1,7 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2015 Andy Wingo <wingo@igalia.com>
 ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
-;;; Copyright © 2017 Clément Lassieur <clement@lassieur.org>
+;;; Copyright © 2017, 2018 Clément Lassieur <clement@lassieur.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -74,11 +74,12 @@
   (documentation configuration-field-documentation))
 
 (define (serialize-configuration config fields)
-  (for-each (lambda (field)
-              ((configuration-field-serializer field)
-               (configuration-field-name field)
-               ((configuration-field-getter field) config)))
-            fields))
+  #~(string-append
+     #$@(map (lambda (field)
+               ((configuration-field-serializer field)
+                (configuration-field-name field)
+                ((configuration-field-getter field) config)))
+             fields)))
 
 (define (validate-configuration config fields)
   (for-each (lambda (field)
@@ -105,7 +106,7 @@
              (define (maybe-stem? val)
                (or (eq? val 'disabled) (stem? val)))
              (define (serialize-maybe-stem field-name val)
-               (when (stem? val) (serialize-stem field-name val)))))))))
+               (if (stem? val) (serialize-stem field-name val) ""))))))))
 
 (define-syntax define-configuration
   (lambda (stx)
@@ -147,7 +148,7 @@
                    conf))))))))
 
 (define (serialize-package field-name val)
-  #f)
+  "")
 
 ;; A little helper to make it easier to document all those fields.
 (define (generate-documentation documentation documentation-name)