From f2882c39c1acb5abc16f49524acb08d6c0b7b1d5 Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adam@chlipala.net>
Date: Fri, 7 Feb 2020 13:53:50 -0500
Subject: List.foldli

---
 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 848bbd5f..1eb7626a 100644
--- a/lib/ur/list.ur
+++ b/lib/ur/list.ur
@@ -31,6 +31,16 @@ fun foldl [a] [b] (f : a -> b -> b) =
         foldl'
     end
 
+fun foldli [a] [b] (f : int -> a -> b -> b) =
+    let
+        fun foldli' i acc ls =
+            case ls of
+                [] => acc
+              | x :: ls => foldli' (i + 1) (f i x acc) ls
+    in
+        foldli' 0
+    end
+
 val rev = fn [a] =>
              let
                  fun rev' acc (ls : list a) =
-- 
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