1 files changed, 14 insertions, 0 deletions
diff --git a/src/list_key_fn.sml b/src/list_key_fn.sml
new file mode 100644
index 00000000..ec2bd26f
--- /dev/null
+++ b/src/list_key_fn.sml
@@ -0,0 +1,14 @@
+functor ListKeyFn(K : ORD_KEY)
+        : ORD_KEY where type ord_key = K.ord_key list = struct
+
+type ord_key = K.ord_key list
+
+val rec compare =
+ fn ([], []) => EQUAL
+  | ([], _) => LESS
+  | (_, []) => GREATER
+  | (x::xs, y::ys) => case K.compare (x, y) of
+                              EQUAL => compare (xs, ys)
+                            | ord => ord
+
+end