02/03: packages: Add 'set-grafting' procedure.

[Ludovic Courtès]

civodul pushed a commit to branch master
in repository guix.

commit b8bedf6051200b0c8eb6ddf4ac1b155466caa3ec
Author: Ludovic Courtès <address@hidden>
Date:   Fri Feb 13 23:07:11 2015 +0100

    packages: Add 'set-grafting' procedure.
    
    * guix/packages.scm (set-grafting): New procedure.
---
 guix/packages.scm |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/guix/packages.scm b/guix/packages.scm
index 96f3adf..5b686a1 100644
--- a/guix/packages.scm
+++ b/guix/packages.scm
@@ -114,6 +114,7 @@
             default-guile
 
             set-guile-for-build
+            set-grafting
             package-file
             package->derivation
             package->cross-derivation
@@ -906,6 +907,12 @@ code of derivations to GUILE, a package object."
     (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