Disambiguate between OCaml and Standard ML

Fix #2208

samples/OCaml/common.ml

@@ -0,0 +1,14 @@
+(*
+ * Copyright (c) 2013 Jeremy Yallop.
+ *
+ * This file is distributed under the terms of the MIT License.
+ * See the file LICENSE for details.
+ *)
+
+let string_of format v = 
+  let buf = Buffer.create 100 in
+  let fmt = Format.formatter_of_buffer buf in begin
+    format fmt v;
+    Format.pp_print_flush fmt ();
+    Buffer.contents buf
+  end