Variables

Variables store program data. var declares a variable that you can assign again. Write its type after its name.

func main() {
    var lives: int = 3
    var bonus = 2
    const maxLives = 10
    external score: int = 0

    lives += bonus
    score += lives
    print(score)
}

lives: int declares an integer. bonus = 2 infers int from the initial value. For a later assignment, declare the type and initialize the variable before reading it.

Common types

Type	Purpose	Example
int	Integers and scoreboard arithmetic	42
float	Floating-point arithmetic	1.5
bool	Conditions	true
string	Strings	"hello"
text	Minecraft chat text	"hello"
nbt	General NBT data	{count: 2}
list<T>	Ordered elements	[1, 2, 3]
dict<T>	String keys and values	{red: 1, blue: 2}
map<T>	A mapping with accessible keys	See Map
entity	A game entity	Obtained through entity APIs
selector	A Minecraft selector	@a

Use data for named fields. Use ScoreRef and NBTRef<T> for game data addresses.

const and external

const permits one assignment. Use it for fixed settings and address references. A fixed reference can still update its target through set.

external requires runtime storage. The example's score uses runtime operations even with an initial value of 0.

The compiler can calculate known ordinary values:

func main() {
    var total = 5
    total += 7
    print(total)
}

The compiler can calculate 12 here. Runtime input causes it to generate commands for the calculation. const describes assignment count. A known value describes what the compiler knows.