gexp: Add 'directory-union'.

* gnu/services.scm (directory-union): Move to...
* guix/gexp.scm (directory-union): ... here.  New procedure.
* doc/guix.texi (G-Expressions): Document it.

1 files changed, 1 insertions, 16 deletions

diff --git a/gnu/services.scm b/gnu/services.scm
index bc866eafe3..50be28a382 100644
--- a/gnu/services.scm
+++ b/gnu/services.scm
@@ -95,9 +95,7 @@
 
             %boot-service
             %activation-service
-            etc-service
-
-            directory-union))
+            etc-service))
 
 ;;; Comment:
 ;;;
@@ -387,19 +385,6 @@ boot."
                  (list (service-extension boot-service-type
                                           cleanup-gexp)))))
 
-(define (directory-union name things)
-  "Return a directory that is the union of THINGS."
-  (match things
-    ((one)
-     ;; Only one thing; return it.
-     one)
-    (_
-     (computed-file name
-                    (with-imported-modules '((guix build union))
-                      #~(begin
-                          (use-modules (guix build union))
-                          (union-build #$output '#$things)))))))
-
 (define* (activation-service->script service)
   "Return as a monadic value the activation script for SERVICE, a service of
 ACTIVATION-SCRIPT-TYPE."