From da80f2aa1cd6326d0fc8621a5cfb0e7fd313e192 Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adam@chlipala.net>
Date: Mon, 15 Aug 2011 10:22:09 -0400
Subject: List.mapXi

---
 lib/ur/list.ur | 10 ++++++++++
 1 file changed, 10 insertions(+)

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

diff --git a/lib/ur/list.ur b/lib/ur/list.ur
index 2679d877..35440de2 100644
--- a/lib/ur/list.ur
+++ b/lib/ur/list.ur
@@ -133,6 +133,16 @@ fun mapX [a] [ctx ::: {Unit}] f =
         mapX'
     end
 
+fun mapXi [a] [ctx ::: {Unit}] f =
+    let
+        fun mapX' i ls =
+            case ls of
+                [] => <xml/>
+              | x :: ls => <xml>{f i x}{mapX' (i + 1) ls}</xml>
+    in
+        mapX' 0
+    end
+
 fun mapM [m ::: (Type -> Type)] (_ : monad m) [a] [b] f =
     let
         fun mapM' acc ls =
-- 
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