From df475a9256347564d3adc1fafc53c4d93b4e73f7 Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adam@chlipala.net>
Date: Sat, 19 May 2012 11:32:12 -0400
Subject: Some standard library additions from Edward Z. Yang

---
 lib/ur/monad.ur | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'lib/ur/monad.ur')

diff --git a/lib/ur/monad.ur b/lib/ur/monad.ur
index 3d03298e..ab7742fe 100644
--- a/lib/ur/monad.ur
+++ b/lib/ur/monad.ur
@@ -12,6 +12,8 @@ fun mp [m] (_ : monad m) [a] [b] f m =
     v <- m;
     return (f v)
 
+val liftM = @@mp
+
 fun foldR [K] [m] (_ : monad m) [tf :: K -> Type] [tr :: {K} -> Type]
           (f : nm :: Name -> t :: K -> rest :: {K}
                -> [[nm] ~ rest] =>
@@ -122,3 +124,8 @@ fun appR3 [K] [m] (_ : monad m) [tf1 :: K -> Type] [tf2 :: K -> Type] [tf3 :: K
          f [nm] [t] r1.nm r2.nm r3.nm)
      (fn _ _ _ => return ())
      fl
+
+fun liftM2 [m ::: Type -> Type] (_ : monad m) [a] [b] [c] (f : a -> b -> c) (mx : m a) (my : m b) : m c =
+    x <- mx;
+    y <- my;
+    return (f x y)
-- 
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