From b8bedf6051200b0c8eb6ddf4ac1b155466caa3ec Mon Sep 17 00:00:00 2001
From: Ludovic Courtès <ludo@gnu.org>
Date: Fri, 13 Feb 2015 23:07:11 +0100
Subject: packages: Add 'set-grafting' procedure.

* guix/packages.scm (set-grafting): New procedure.
---
 guix/packages.scm | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/guix/packages.scm b/guix/packages.scm
index 96f3adfc32..5b686a122f 100644
--- a/guix/packages.scm
+++ b/guix/packages.scm
@@ -114,6 +114,7 @@ (define-module (guix packages)
             default-guile
 
             set-guile-for-build
+            set-grafting
             package-file
             package->derivation
             package->cross-derivation
@@ -906,6 +907,12 @@ (define (set-guile-for-build guile)
     (let ((guile (package-derivation store guile)))
       (values (%guile-for-build guile) store))))
 
+(define (set-grafting enable?)
+  "This monadic procedure enables grafting when ENABLE? is true, and disables
+it otherwise.  It returns the previous setting."
+  (lambda (store)
+    (values (%graft? enable?) store)))
+
 (define* (package-file package
                        #:optional file
                        #:key
-- 
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