1 files changed, 3 insertions, 0 deletions
diff --git a/lib/hMap.mli b/lib/hMap.mli
index 4519ba316a..45b722fda0 100644
--- a/lib/hMap.mli
+++ b/lib/hMap.mli
@@ -10,7 +10,10 @@ module type HashedType =
 sig
   type t
   val compare : t -> t -> int
+  (** Total ordering *)
   val hash : t -> int
+  (** Hashing function compatible with [compare], i.e. [compare x y = 0] implies
+      [hash x = hash y]. *)
 end
 
 (** Hash maps are maps that take advantage of having a hash on keys. This is