store.ts

type Transition<State, Operation> = (state: State, operation: Operation) => State;

class Store<State, Operation> {
    private initialState: State;
    private operations: Operation[] = [];
    private transition: Transition<State, Operation>;
    private currentState: State;

    constructor(initialState: State, transition: Transition<State, Operation>) {
        this.initialState = initialState;
        this.transition = transition;
        this.currentState = initialState;
    }

    public commit(operation: Operation) {
        this.operations.push(operation);
        this.currentState = this.transition(this.currentState, operation);
    }

    public commitAll(operations: Operation[]) {
        for (const operation of operations) this.commit(operation);
    }
}