Contributed by gautam-e

Tuple

Tuple literal, consists of zero or more values separated by commas.

init

These are the same, as Tuple can be elided when using () brackets:

let t = (1, 2, 3)
let t = Tuple(1, 2, 3)

You can also use different types inside the tuple, and can be implicit or explicit with the types:

let u = ("string", 5.0, 2)
let v: Tuple[StringLiteral, FloatLiteral, Int] = ("string", 5.0, 2)

length

Number of elements in the tuple.

print("Length of the tuple:", len(t))

Length of the tuple: 3

get

Get a specific element in the tuple.

print(u.get[1, FloatLiteral]())

5.0

limitations

You can't get items from a tuple if it's not @register_passable:

@value
struct Coord:
    var x: Int
    var y: Int

var x = (Coord(5, 10), 5.5)

let y = x.get[0, Coord]()
print(y.data[0].x)

error: Expression [2]:23:28: invalid call to 'get': result cannot bind generic !mlirtype to memory-only type 'Coord'
    let y = x.get[0, Coord]()
            ~~~~~~~~~~~~~~~^~

/.modular/Kernels/mojo/Builtin/Tuple.mojo:58:5: function declared here
    fn get[i: Int, T: AnyType](self) -> T:
    ^

To remedy this you can mark it as @register_passable, but it must contain all register passable types:

@value
@register_passable
struct Coord:
    var x: Int
    var y: Int

var x = (Coord(5, 10), 5.5)

print(x.get[0, Coord]().x)

5

So items like a String won't work.