Version: Next

Cheat Sheet

Contract, view and test

namespace C {
  export type storage = int;

  @entry
  const increment = (action: int, store: storage) : [list <operation>, storage] => [[], store + action];

  @entry
  const decrement = (action: int, store: storage) : [list <operation>, storage] => [[], store - action];

  @view
  const get_storage = (must_be_positive: bool, storage: int): int => {
    if (must_be_positive && storage < 0) {
      return failwith("Negative value in storage");
    } else {
      return storage;
    }
  }
};

const testC = do {
    let initial_storage = 42;
    let originated = Test.originate(contract_of(C), initial_storage, 0mav);
    let p : parameter_of C = Increment(1);
    Test.transfer_exn(originated.addr, p, 1mumav);
    return assert(Test.get_storage(originated.addr) == initial_storage + 1);
}

Strings

const name: string = "Mavryk";

Characters

const t: string = "t";

Integers

const i: int = 42;

Natural numbers

const n: nat = 7n;

Unit

const u: unit = unit;

Boolean

const has_drivers_license: bool = false
const adult: bool = true

Boolean Logic

const booleanLogic: bool =
    (!true) ==
    false ==
    (false && true) ==
    (false || false)

Mumav (micro mav)

const mav_amount: mav = 42mav
const mav_amount2: mav = mav_amount + 7mumav // == 42000007mumav

Address

const tz1address: address = "mv18Cw7psUrAAPBpXYd9CtCpHg9EgjHP9KTe";
const kt1address: address = "KT1JepfBfMSqkQyf9B1ndvURghGsSB8YCLMD";

String

const my_str : string = "Hello World!";

Verbatim string

const verbatim_str : string = `verbatim string`;

Addition

const add_int: int = 3 + 4;
const add_nat: nat = 3n + 4n;

Multiplication & Division

const mul_int: int = 3 * 4;
const mul_nat: nat = 3n * 4n;

const div_int: int = 10 / 5;
const div_nat: nat = 10n / 5n; // can fail (division by zero), check your inputs first.

Modulo

const mod_nat: nat = 10 % 3; // can fail (division by zero), check your inputs first.

Tuples

type name = [string, string];

const winner: name = ["John", "Doe"];

const firstName: string = winner[0];
const lastName: string = winner[1];

Types

type age = int
type name = string

Include (prefer import)

#include "library.jsligo"

Import (better)

#import "library.jsligo" "MyLibrary"
const foo = MyLibrary.bar;

Functions (short form)

const add = (a: int, b: int): int =>
  a + b;

Functions (long form)

const add = (a: int, b: int): int => {
  let c = a;
  let d = b;
  return c + d
};

If/else Statement

function if_statement (age : nat): string {
  if (age >= 16n) return "yes" else return "no"
}

Options

type middle_name = option<string>;
const a_middle_name : middle_name = Some("Foo");
const no_middle_name : middle_name = None();

Variable Binding

const age: int = 5

Type Annotations

const someAddress: address = "mv18Cw7psUrAAPBpXYd9CtCpHg9EgjHP9KTe";

Variants (label + optional value)

type action =
  ["Increment", int]
| ["Decrement", int]
| ["Reset"];

Matching on variant cases

let a: action = Increment(5)
const result: int = match(a) {
  when(Increment(n)): n + 1;
  when(Decrement(n)): n - 1;
  when(Reset()): 0;
}

Records / Plain Old Data Objects

type person = {
  age: int,
  name: string
}

const john : person = {
  age: 18,
  name: "john doe"
}

const name_: string = john.name

Maps

type prices = map<nat, mav>;

const prices: prices = Map.literal([
  [10n, 60mumav],
  [50n, 30mumav],
  [100n, 10mumav]
]);

const price: option<mav> = Map.find_opt(50n, prices)

const prices2: prices = Map.update(200n, Some (5mumav), prices)

Contracts & Accounts

const destinationAddress: address = "mv18Cw7psUrAAPBpXYd9CtCpHg9EgjHP9KTe";

const contract : contract<unit> =
  match(Mavryk.get_contract_opt(Mavryk.get_sender()) as option<contract<unit>>) {
    when(Some(contract)): contract;
    when(None()): failwith("no contract or wrong contract type")
  }

Transactions

const payment: operation =
  Mavryk.transaction(unit, 100mumav, contract);

Exception/Failure

const fail = (u: unit) : unit =>
  failwith("a failure message")

Comb layout (default)

type animal =
@layout("comb")
| ["Elephant"]
| ["Dog"]
| ["Cat"];

Tree layout

type animal =
@layout("tree")
| ["Elephant"]
| ["Dog"]
| ["Cat"];

Namespace (auto-inferred type)

namespace FA0_inferred {
  type storage = int;
  @entry const add = (s : int, k : int) : [list<operation>, int] => [[], s + k];
  @entry const extra = (s : int, k : int) : [list<operation>, int] => [[], s - k];
}

Interface

interface FA0_INTF {
  type storage;
  @entry const add : (s : int, k : storage) => [list<operation>, storage];
}

Extending Interface

interface FA0_EXT_INTF extends FA0_INTF {
  type storage;
  @entry const add : (s : int, k : storage) => [list<operation>, storage];
}

Namespace impmlementing

namespace FA0 implements FA0_INTF {
  export type storage = int;
  @entry const add = (s : int, k : int) : [list<operation>, int] => [[], s + k];
  @entry const extra = (s : int, k : int) : [list<operation>, int] => [[], s - k];
}

Extending namespace

Not available in JsLIGO, use CameLIGO.