Essence of Hooks

Hooks.re

let foo = (~name, ~surname, _) => {
  print_string("name: " ++ name);
  print_string("surname: " ++ surname);
};

module State: {
  type t('a);
  let init: 'a => t('a);
  let get: t('a) => 'a;
  let set: (t('a), 'a) => unit;
} = {
  type t('a) = ref('a);
  let init = (s: 'a): t('a) => ref(s);
  let get = x => x^;
  let set = (x, y) => x := y;
};

module Event = {
  let onClick = f =>
    if (Random.bool()) {
      let choices = [|"some", "random", "words"|];
      let n = choices->Array.length;
      choices[Random.int(n)]->f;
    };
};

let foo2 =
    (
      ~name,
      ~stateName=State.init(name),
      ~surname,
      ~stateSurname=State.init(surname),
      _,
    ) => {
  Event.onClick(s => stateName->(State.set(s)));
  Event.onClick(s => stateSurname->(State.set(s)));
  print_string("name: " ++ stateName->State.get);
  print_string("surname: " ++ stateSurname->State.get);
};
let main = () => foo(~name="Mary", ());

let main2 = () => foo2(~name="Mary", ());