From 0cadb1a719bc515af2449ac966e545a6599aee4d Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adam@chlipala.net>
Date: Sat, 14 Apr 2018 15:15:07 -0400
Subject: List.findM

---
 lib/ur/list.ur | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

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

diff --git a/lib/ur/list.ur b/lib/ur/list.ur
index a7296552..95d6fbc8 100644
--- a/lib/ur/list.ur
+++ b/lib/ur/list.ur
@@ -255,6 +255,21 @@ fun find [a] f =
         find'
     end
 
+fun findM [m] (_ : monad m) [a] f =
+    let
+        fun find' ls =
+            case ls of
+                [] => return None
+              | x :: ls =>
+                b <- f x;
+                if b then
+                    return (Some x)
+                else
+                    find' ls
+    in
+        find'
+    end
+
 fun search [a] [b] f =
     let
         fun search' ls =
-- 
cgit v1.2.3