I am trying to use lambda's constructor [1] with fusion's fused [2]. Fused requires that the function object passed to it has a following valid expression: boost::result_of< F(T1 ...TN) >::type Unfortunately, constructor does not support result_of. Its implementation contains the following piece of code: template <class U> struct sig { typedef T type; }; This happens to be exactly what's necessary for constructor to support result_of, but sig would have to be renamed to result. I guess I do not really have a question here but rather a request to make constructor compatible with result_of. There seems to be no reason not to do it, and I could not figure out a much nicer way to construct objects with fusion sequences than combining lambda's constructor and fusion's fused. It comes so close, but if only sig was result... Cheers, Marcin [1] http://www.boost.org/doc/libs/1_42_0/doc/html/lambda/le_in_details.html#lamb... [2] http://www.boost.org/doc/libs/1_42_0/libs/fusion/doc/html/fusion/functional/...