1 files changed, 4 insertions, 0 deletions
diff --git a/lib/Utilities.ml b/lib/Utilities.ml
index e4ee9c3..9bff69b 100644
--- a/lib/Utilities.ml
+++ b/lib/Utilities.ml
@@ -39,6 +39,10 @@ module List = struct
   end
 
   include Generic (ListSequence)
+
+  let hd_opt = function
+    | x::_ -> Some x
+    | [] -> None
 end
 
 module FingerTree = struct