type storage = int

type parameter =
  Increment of int
| Decrement of int
| Reset

type return = operation list * storage

(* Two entrypoints *)

let add (store, delta : storage * int) : storage = store + delta
let sub (store, delta : storage * int) : storage = store - delta

(* Main access point that dispatches to the entrypoints according to
   the smart contract parameter. *)

let main (action, store : parameter * storage) : return =
 ([] : operation list),    // No operations
 (match action with
   Increment (n) -> add (store, n)
 | Decrement (n) -> sub (store, n)
 | Reset         -> 0)