--- gui/model/representation.cpp.orig 2014-07-01 20:45:39.000000000 +0200 +++ gui/model/representation.cpp 2014-07-01 20:46:02.000000000 +0200 @@ -1,4 +1,5 @@ #include "representation.h" +#include std::ostream &operator<<(std::ostream& os, const representation::t& r) {