State machines

Yeah, so I'm going to add explicit state machines support to the language. It looks like this:

state-machine

  start {

    # Figure stuff out.

    => a1

    => b1

  }

  a1 {

    # Other stuff.

    => return

    ...

You can parameterize a state machine:

state-machine (input)

  ...

Put like this, a state machine is itself an action (e.g. a "do" that runs on ->go()). You can also simply declare a state machine and instantiate it on input elsewhere, in which case the instance will be a ....

[we interrupt this post to point out that FSA::Rules really does.]

... function that you can call repeatedly. And thanks to FSA::Rules, all the hard work is done; I can just wrap it. The only question remaining being whether state machines belong in the core or not. Actually, I think not. Which means I have to figure out how to chain semantic domains (but I had to figure that out eventually anyway).