Tickets

The following functions are available under the Tezos. namespace.

val Tezos.create_ticket : 'value -> nat -> ('value ticket) option

let Tezos.create_ticket: 'value => nat => option<ticket<'value>>

To create a ticket, the value and the amount of tickets to be created needs to be provided. The ticket will also contain the contract address it originated from (which corresponds to Tezos.self). The resulting value is None if the amount is zero.

let my_ticket1 = Option.unopt (Tezos.create_ticket 1 10n)
let my_ticket2 = Option.unopt (Tezos.create_ticket "one" 10n)

const my_ticket1 = Option.unopt(Tezos.create_ticket(1, 10n));
const my_ticket2 = Option.unopt(Tezos.create_ticket("one", 10n));

val Tezos.read_ticket : 'value ticket -> (address * ('value * nat)) * 'value ticket

let Tezos.read_ticket: ticket<'value> => <<address, <'value , nat>> , ticket<'value>>

Reading a ticket will return a tuple with the ticket address, the value and the same ticket for later use. A ticket is only consumed when it is dropped (e.g. DROP-ed from the Michelson stack) so if the returned ticket isn't stored in some form by your contract, it will be fully consumed.

To read the content of a ticket, you can either use tuple destructuring or pattern matching:

let v =
  let (_addr, (payload, _amt)), _ticket = Tezos.read_ticket my_ticket1
  in payload

To read the content of a ticket, you need to use tuple destructuring:

const v2 = do {
  let [[_addr, [payload, _amt]], _ticket] = Tezos.read_ticket (my_ticket2);
  return payload;
}

val Tezos.split_ticket : 'value ticket -> nat * nat -> ('value ticket * 'value ticket) option

let Tezos.split_ticket: ticket<'value> => <nat , nat> => option <<ticket<'value>, ticket<'value>>>

To partially use/consume a ticket, you have to split it. Provided a ticket and two amounts, two new tickets will be returned to you if, and only if, the sum equals to the amount of the original ticket.

let ta, tb =
  match Tezos.split_ticket my_ticket1 (6n, 4n) with
    None -> failwith "amt_a + amt_v <> amt"
  | Some split_tickets -> split_tickets

const [ta, tb] =
  match(Tezos.split_ticket(my_ticket1, [6n, 4n])) {
    when(None()): failwith("amt_a + amt_v != amt");
    when(Some(split_tickets)): split_tickets
  };

val Tezos.join_tickets : 'value ticket * 'value ticket -> ('value ticket) option

let Tezos.join_tickets = <ticket<'value>, ticket<'value>> => option <ticket<'value>>

To add two tickets, you have to join them. This works as the inverse of Tezos.split_ticket. Provided two tickets with the same ticketer and content, they are deleted and a new ticket will be returned with an amount equal to the sum of the amounts of the input tickets.

let tc : int ticket option =
  let ta = Option.unopt (Tezos.create_ticket 1 10n) in
  let tb = Option.unopt (Tezos.create_ticket 1 5n) in
  Tezos.join_tickets (ta, tb)

const ta = Option.unopt(Tezos.create_ticket(1, 10n));
const tb = Option.unopt(Tezos.create_ticket(1, 5n));
const tc = Tezos.join_tickets([ta, tb]);