adding more experimental code

h2/lib2/h3-trees.ads

@@ -0,0 +1,43 @@
+use H3.Arrays;
+
+package H3.Trees is
+
+	-- parse tree
+
+	--package A is new H3.Arrays(XXXX, 0);
+
+	type Node_Code is (
+		NODE_ASSIGN,
+		NODE_CALL,
+		NODE_CLASS
+		NODE_IF,
+		NODE_FUN,
+		NODE_VOID,
+		NODE_WHILE
+	);
+
+	type Node(Code: Node_Code := NODE_VOID) is record
+		-- Loc: location.
+		case Code is
+			when NODE_ASSIGN =>
+				null;
+			when NODE_CALL =>
+				null;
+			when NODE_CLASS =>
+				null;
+			when NODE_IF =>
+				null;
+			when NODE_FUN =>
+				null;
+			when NODE_VOID =>
+				null;
+			when NODE_WHILE =>
+				null;
+	end record;
+
+	type Tree is record
+		Next_Node: System_Index := System_Index'First;
+		Toplevel_Node := Node
+	end Tree;
+
+end H3.Trees;