type storage is int

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

type return is list (operation) * storage

(* Two entrypoints *)

function add (const store : storage; const delta : int) : storage is store + delta

function sub (const store : storage; const delta : int) : storage is store - delta

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

function main (const action : parameter; const store : storage) : return is
 ((nil : list (operation)),    // No operations
  case action of
    Increment (n) -> add (store, n)
  | Decrement (n) -> sub (store, n)
  | Reset         -> 0
  end)