Great point – I should definitely have mentioned Julia as your best bet for playing around with multi-methods. I think it's basically the only language with any eco-system to speak of that has them. Julia also happens to be the only extant language I'm aware of that has a well designed shell interpolation syntax. For resumable exceptions, however, playing around with Dylan or CL remains your best bet, as far as I'm aware of (and Common Lisp at least also integrates them into the interactive development experience).