All you need is a GADT which carries around the type class constraint. data Object cls a where Object :: cls a => a -> Object cls a Now, the class `

All you need is a GADT which carries around the type class constraint. data Object cls a where Object :: cls a => a -> Object cls a Now, the class `cls a` is carried around with the value `a`. You can even go one step further and reify the vtable by itself. data Dict c where Dict :: c => Dict which you can't really do in standard C++.