From 0156bf0da091dd2a773c08c2917c121bc86643bb Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adam@chlipala.net>
Date: Fri, 19 Aug 2011 15:23:01 -0400
Subject: Basis.mkMonad

---
 lib/ur/option.ur | 6 ++++++
 1 file changed, 6 insertions(+)

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

diff --git a/lib/ur/option.ur b/lib/ur/option.ur
index 0aa07a2d..5c89fc9d 100644
--- a/lib/ur/option.ur
+++ b/lib/ur/option.ur
@@ -1,5 +1,11 @@
 datatype t = datatype Basis.option
 
+val monad = mkMonad {Return = @@Some,
+                     Bind = fn [a] [b] (m1 : t a) (m2 : a -> t b) =>
+                               case m1 of
+                                   None => None
+                                 | Some v => m2 v}
+
 fun eq [a] (_ : eq a) =
     mkEq (fn x y =>
              case (x, y) of
-- 
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