I made a new attempt to make State and Trigger generic based on the latest master branch (see master...suhlig:qmuntal-stateless:generic). Tests are passing, so I believe it is ready to be merged.

While I agree that the benefit is not huge, generic type parameters improve one important thing: As I am hiding the state machine behind my project's API, generic type parameters allow me to have State and Trigger be a type of my domain, so that my API does not leak stateful.State to its users.

I was also briefly thinking about the parameters to triggers and guard functions. I believe generics would be much more helpful to define the type and arity of parameters, but I wouldn't know how to achieve that without an explosion of type parameters (basically one for each distinct trigger + guard parameter).

Overall, stateless as been a pleasure to work with. Keep up the good work!

I also have been thinking about this and starting with @suhlig work, I considered adding an Argument generic type as well.

#88

As I mentioned in that pull request, it does add some verbosity to the core stateless code, but at least for my typical use cases, I usually don't have dynamic typing for my arguments, so it would be more convenient when writing software which uses the library. Anyway, it's provided mostly as taking a crack at it to see what it would look like.