compose.ts

function compose<T>(...fna: Array<(p: T) => Promise<T>>) {
  return (p: T) => {
    return fna.reduce((a, fn) => a.then(fn), Promise.resolve(p));
  };
}

const pipe = compose(foo, bar, baz);
const res1 = pipe(arg);

// equivalent
const res2 = foo(arg).then(bar).then(baz);