type storage = int;

/* variant defining pseudo multi-entrypoint actions */

type action =
  | Increment(int)
  | Decrement(int);

let add = (a: int, b: int): int => a + b;
let sub = (a: int, b: int): int => a - b;

/* real entrypoint that re-routes the flow based on the action provided */

let main = (p: action, storage) => {
  let storage =
    switch (p) {
    | Increment(n) => add(storage, n)
    | Decrement(n) => sub(storage, n)
    };
  ([]: list(operation), storage);
};