Add variance indicator to type.

diff --git a/src/node.ml b/src/node.ml
index 78f0899..abf75a4 100644 (file)
--- a/src/node.ml
+++ b/src/node.ml
@@ -1,4 +1,4 @@
-type 'a t = int
+type +'a t = int
 
 
 let nil = ~-1

diff --git a/src/node.mli b/src/node.mli
index 2aecb70..84472ac 100644 (file)
--- a/src/node.mli
+++ b/src/node.mli
@@ -1,4 +1,4 @@
-type 'a t = private int
+type +'a t = private int
 val nil : 'a t
 val null : 'a t
 val is_nil : 'a t -> bool