1 files changed, 18 insertions, 0 deletions
diff --git a/src/expressions/sym_type.ml b/src/expressions/sym_type.ml
new file mode 100755
index 0000000..31c9534
--- /dev/null
+++ b/src/expressions/sym_type.ml
@@ -0,0 +1,18 @@
+module type SYM_TYPE = sig
+
+  type 'a t
+
+  type 'a obs
+
+  val str :  DataType.String.t -> DataType.String.t t
+
+  val num :  DataType.Num.t -> DataType.Num.t t
+
+  val date:  DataType.Num.t -> DataType.Num.t t
+
+  val bool : DataType.Bool.t -> DataType.Bool.t t
+
+  val observe : 'a t -> 'a obs
+
+end
+