Patchinko's overloaded module re-written in terse yet spacious expressions (source: https://github.com/barneycarroll/patchinko/blob/master/overloaded.js)

overloaded-patchinko.js

export default function O(a){
  return (
    arguments.length == 1
  ? 
      typeof a != 'function'
    ? 
      new O(a => O(b, a))
    :
        this instanceof O
      ? 
        (
          this.apply = b => a(b),
          this
        )
      : 
        new O(b)
  : 
    [...arguments].reduce(({}, b) => (
      Object.entries(b).forEach(([key, val]) => (
        val == O
      ? 
        delete a[key]
      : 
        a[key] = 
            val instanceof O
          ? 
            val.apply(a[key])
          : 
            val
      )),
      a
    ))
  )
}