1 files changed, 12 insertions, 0 deletions
diff --git a/src/expressions/sym_ref.ml b/src/expressions/sym_ref.ml
new file mode 100755
index 0000000..aba8053
--- /dev/null
+++ b/src/expressions/sym_ref.ml
@@ -0,0 +1,12 @@
+module type SYM_REF = sig
+
+  type 'a t
+
+  type 'a obs
+
+  val cell : Cell.t -> 'a t
+
+  val range : Cell.t -> Cell.t -> 'a t
+
+  val observe : 'a t -> 'a obs
+end