function composition with `.` in javascript

dot.js

const accumulator = (fns) => {
  const fn = () => {};
  fn.fns = fns;
  return fn;
}

const handler = {
  get: (target, fn) => {
    return new Proxy(accumulator([...target.fns, fn]), handler);
  },
  apply: (target, thisArg, args) => {
    return target.fns.reduce((acc, fn) => x => acc(window[fn](x)), x => x)(args);
  },
}

const λ = new Proxy(accumulator([]), handler);

window.duplicate = x => [x, x];
window.multiplyBy = a => b => a * b;
window.multiplyBy2 = multiplyBy(2);

console.log((λ . duplicate . multiplyBy2)(10));