Playful Haskell Stream I/O with ES6 Generators

streamio.js

function *main() {
  const confirmRequest = {
    type: 'confirm', 
    value: 'Are you sure?',
  };
  const confirmResponse = yield confirmRequest;
  
  if (confirmResponse === true) {
    const consoleRequest = {
      type: 'console', 
      value: 'You are sure',
    };
    yield consoleRequest;
  } else {
    const consoleRequest = {
      type: 'console', 
      value: 'You are not sure',
    };
    yield consoleRequest;
  }
}

function run(mainFn) {
  requests = mainFn();
  let next = requests.next();
  while (!next.done) {
    const request = next.value;
    let response = null;
    if (request.type === 'console') {
      console.log(request.value);
    } else if (request.type === 'confirm') {
      response = window.confirm(request.value);
    }
    next = requests.next(response);
  }
}

run(main);

The program above is equivalent to

var response = window.confirm('Are you sure');
if (response === true) {
  console.log('You are sure');
} else {
  console.log('You are not sure');
}