Todo.txt

* Work on error messages. They should be of the form:

 In starting state: "S", when taking action A with these params: "P", the implementation does not conform to the model.

 A path to starting state S is: [A0, A1, A2... ] 

  Finding a path to the starting state is not absolutely necessary, though it might be very helpful for debugging.

* Integrate js_of_ocaml and use it for AST definitions and codegen - maybe not codegen, because
   there are some idiosyncrasies of Sligh.

* Design external system interfaces, i.e. Stripe API or another internal service. Probably 
  algebraic effects or monads?

* Formalize property compiliation? Some slightly tricky things go on during compilation, and it's important to 
  know that the generated properties actually say what we want them to. The correctness statement would be:

  "When properties are generated with the formalized compilation procedure, they imply correctness of the whole system."

* Design "Distributed State Protocol." To test distributed systems, we need a way to deterministically
  write and read system state. This is currently done via simple 'setup', 'read', and 'teardown' endpoints, where
  the required state to read or create is sent as a single object payload, a la graphql.

* Build out 'model explorer', interpreter + debugging tools
   * Generate template for action sequence - for example, select 3 actions, show a template for an initial state.
    then provide params for each action input in the sequence
   * Browse actions - observe what can be done in the system

* Separate concrete from abstract syntax. Example: state variables are just identifiers
  in concrete syntax, but can be elaborated to a separate state var node in abstract syntax.
  This gives more semantic information to identifiers so that all usages of them are aware if
  they're a state variable or not.

* Idea: Collector - add custom model analyses

* Support custom data generators, probably per-action, and using something like Luck or 
  or combinatorial testing with sparse regular tree expressions: https://link.springer.com/content/pdf/10.1007/978-3-030-72019-3_10.pdf 

* Support swarms, i.e. limiting tests to groups of actions. i.e.:
  action_sets:
    completion: [TodoMvc.AddTodo, TodoMvc.MarkComplete] end
    uncompletion: [TodoMvc.AddTodo, TodoMvc.Somethin]
  end

* Documentation. What builtins are available and what the schema is of the syntax type hierarchy
  is totally opaque right now. 

* Type system. The foundation is there syntactically, but no actual type checking is performed
  right now.  

* VSCode plugin.

* Get back to experimenting with implementation derivation via effects.