Processing Constraints and Preferences on Sequences, Recognizing Sequences, Automata, and Reactive Patterns

[AdamSobieski]

Hello. Here is a sketch from a project of mine (Nifty) of a sequence recognizer based on System.IObserver<>:

public interface IObserver<in TAlphabet>
{
    public bool Continue { get; }
    public bool Recognized { get; }

    public void OnCompleted();
    public void OnError(Exception error);
    public IObserver<TAlphabet> OnNext(TAlphabet value);
}

The OnNext() method returns an IObserver<> which represents, or maps with, a next state from an automaton.

The Boolean Continue property indicates that, from the current state, future sequences may exist which could be Recognized.

The Boolean Recognized property indicates that, at the current state, the input sequence is valid.

These concepts are useful for heuristic search, automated planning, and for otherwise recognizing valid sequences. I'm considering approaches, e.g., fluent approaches, for describing and specifying such automata.

Any thoughts on these topics blending reactive patterns and automata theory? If not this interface, how would you design such an interface? Thank you.