TMPでcase ref: http://qiita.com/minamiyama1994/items/b8f1185ed93b6835c239

example1.cpp

case_ < char >::of
<
    match < char , long > ,
    match < short , int > ,
    match < int , short > ,
    match < long , char > ,
    match < list < pattern < 0 > , double > , list < double , pattern < 0 > > >
>::type // => long

example2.cpp

case_ < list < float , double > >::of
<
    match < char , long > ,
    match < short , int > ,
    match < int , short > ,
    match < long , char > ,
    match < list < pattern < 0 > , double > , list < double , pattern < 0 > > >
>::type // => list < double , float >