Update Functional.hh

lgtrombetta · web-flow · commit 2691aac94594 · 2017-07-14T19:45:40.000-03:00
diff --git a/core/Functional.hh b/core/Functional.hh
@@ -1,6 +1,7 @@
 
 #pragma once
 
+#include <functional>
 #include "Storage.hh"
 
 namespace cadabra {
