# Top-Level

These types and functions are available without any needed prefix.

type address

An untyped address which can refer to a smart contract or account.

type big_map <'key, 'value>

The type of a big map from values of type `key`

to
values of type `value`

is `big_map<key, value>`

.

Be aware that a `big_map`

cannot appear inside another `big_map`

.

type bool

type bytes

type contract<'param>

A typed contract.

Use `unit`

as `param`

to indicate an implicit account.

type chain_id

The identifier of a chain, used to indicate test or main chains.

type int

An integer.

The only size limit to integers is gas.

type key

A public cryptographic key.

type key_hash

The hash of a public cryptographic key.

type list<'t>

A sequence of elements of the same type.

type map <'key, 'value>

The type of a map from values of type `key`

to
values of type `value`

is `map <key, value>`

.

type nat

A natural number.

The only size limit to natural numbers is gas.

type operation

An operation emitted by the contract

type set<'value>

type signature

A cryptographic signature.

type string

A sequence of characters.

type tez

A specific type for tokens.

type timestamp

A date in the real world.

type unit

let is_nat: (i: int) => option<nat>

Convert an `int`

to a `nat`

if possible.

let abs: (i: int) => nat

Cast an `int`

to `nat`

.

let int: (n: nat) => int

Cast an `nat`

to `int`

.

let unit: unit

A helper to create a unit.

let failwith: (message: 'a) => 'b

Cause the contract to fail with an error message or integer. Other types are not supported at the moment.

Using this currently requires in general a type annotation on the
`failwith`

call.

let assert: (condition: bool) => unit

Check if a certain condition has been met. If not the contract will fail.

let ediv: (value: int, divided_by: int) => option<[int, nat]>

let ediv: (value: mutez, divided_by: nat) => option<[mutez, mutez]>

let ediv: (value: mutez, divided_by: mutez) => option<[nat, mutez]>

let ediv: (value: nat, divided_by: nat) => option<[nat, nat]>

Compiles to Michelson `EDIV`

, one operation to get both the quotient and remainder of a division. `ediv x y`

returns None if `y`

is zero, otherwise returns `Some (quotient, remainder)`

such that `x = (quotient * y) + remainder`

and `0 <= remainder < abs(y)`

.

let ignore: (value: 'a) => 'unit

Ignores a value, it can be an alternative to `_`

prefixed variables.

Edo protocol introduced the following ticket type. Follow this wallet example for an example of correct usage (it goes with its builder). This article might also be useful.

Note that a variable containing a ticket can only be used once (they are not `DUP`

-able).

The ticket type can be defined over a comparable type `'v`

.
`'v`

being the type of the value used to identify a given ticket.

type tx_rollup_l2_address

A type used to identify accounts on transaction rollupsâ€™ legders. Values of type tx_rollup_l2_address are 20-byte hashes of a BLS public keys (with a string notation based of a base58 encoding, prefixed with tz4).