.js

import { log } from "./log.js";
import { State } from "./state.js";
import { match } from "./utils.js";
// javascript implementation of the example - 1 of the State monad in hasklell
//https://wiki.haskell.org/State_Monad#Complete_and_Concrete_Example_1

var playGame = charSequence =>
  match(charSequence)({
    // pattern matching on the array
    empty: () => State(s => s), //terminates
    cons: (x, xs) =>
      State(({ on, counter }) => {
        if (x == "a" && on) 
          return { state: { on: on, counter: counter + 1 } };
        else if (x == "b" && on)
          return { state: { on: on, counter: counter - 1 } };
        else if (x == "c") 
          return { state: { on: !on, counter: counter } };
      }).bind(_ => playGame(xs))
  });

var startGame = charSequence =>
  playGame(charSequence).run({ on: true, counter: 0 });

var display = resultState => log(JSON.stringify(resultState));

display(startGame(Array.from("aa")));