From b307c06456eefa10ebe59216599f554dae641cd6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Tue, 2 Dec 2014 10:10:51 +0100
Subject: [PATCH] monads: Add 'lift0'.

* guix/monads.scm (lift0): New variable.
---
 guix/monads.scm | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/guix/monads.scm b/guix/monads.scm
index 52cb3f5ed0..65683e65de 100644
--- a/guix/monads.scm
+++ b/guix/monads.scm
@@ -41,7 +41,7 @@
             mbegin
             mwhen
             munless
-            lift1 lift2 lift3 lift4 lift5 lift6 lift7 lift
+            lift0 lift1 lift2 lift3 lift4 lift5 lift6 lift7 lift
             listm
             foldm
             mapm
@@ -222,6 +222,7 @@ CONDITION is true, return *unspecified* in the current monad."
          (with-monad monad
            (return (proc args ...))))))))
 
+(define-lift lift0 ())
 (define-lift lift1 (a))
 (define-lift lift2 (a b))
 (define-lift lift3 (a b c))