2 files changed, 14 insertions(+), 1 deletions(-)

M guix/store.scm
M tests/store.scm

@@ 99,6 99,7 @@
             store-bind
             store-return
             store-lift
+            store-lower
             run-with-store
             %guile-for-build
             text-file


@@ 881,6 882,12 @@ in the store monad."
                         (procedure-property proc 'documentation))
   result)
 
+(define (store-lower proc)
+  "Lower PROC, a monadic procedure in %STORE-MONAD, to a \"normal\" procedure
+taking the store as its first argument."
+  (lambda (store . args)
+    (run-with-store store (apply proc args))))
+
 ;;
 ;; Store monad operators.
 ;;

@@ 1,5 1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012, 2013, 2014 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2012, 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;


@@ 595,6 595,12 @@ Deriver: ~a~%"
            (null? (valid-derivers %store file))
            (null? (referrers %store file))))))
 
+(test-equal "store-lower"
+  "Lowered."
+  (let* ((add  (store-lower text-file))
+         (file (add %store "foo" "Lowered.")))
+    (call-with-input-file file get-string-all)))
+
 (test-end "store")