Serial queue solution using lambda calculus.

lambda-queue.js

const empty =
  run =>
    run()
const enqueue =
  (q, fn) =>
    next =>
      q(() => fn(next))


let q = empty

q = enqueue(q, function(done){
  console.log('first');
  done();
});

q = enqueue(q, function(done){
  console.log('second');
  done();
});

q = enqueue(q, function(done){
  setTimeout(function(){
    console.log('third')
    done()
  }, 1000)
});

q = enqueue(q, function(done){
  console.log('final task');
  done();
});

// runs the tasks
q(function(){
  console.log('done');
});