btw this could (sorta) be considered a special case of the fact that a tuple/struct (product type) can be represented as a function:

  let pair = (a, b) => (
    (ix) => (
      ix === 0 ? a :
      ix === 1 ? b :
      undefined
    )
  );

  
  let p = pair(3, "foo");
  p(0) // 3
  p(1) // "foo"

i've seen sth like this used as the definition of tuples in a math context. (there are also other ways to do it too, like church/scott encoding)

however the object has the extra wrinkle of self-referentiality, because the `self` function is defined recursively