Structs

Structs

Structs are nominal record types declared with named fields. Methods are attached in impl blocks.

Declaring a struct

struct Point:
  x: i32
  y: i32

Fields are declared one per line inside the indented body.

Using a struct type

struct Point:
  x: i32
  y: i32

func sum(point: Point) -> i32:
  return point.x + point.y

Field access uses . and is typechecked against the declared struct shape.

Nested structs

struct Point:
  x: i32
  y: i32

struct Rect:
  origin: Point
  width: i32
  height: i32

func perimeter_seed(rect: Rect) -> i32:
  return rect.origin.x + rect.origin.y + rect.width + rect.height

Impl blocks

Methods live in an impl block named after the target struct:

struct Counter:
  value: i32

impl Counter:
  func current(self) -> i32:
    return self.value

  func bump(self) -> i32:
    return self.value + 1

The current method model uses an explicit self parameter.

Generic struct surface

The parser also accepts generic struct syntax:

struct Vec<T>:
  data: ptr
  len: i32

That syntax is part of the current AST and parser surface, but generic structs and generic impl blocks are not yet fully available end to end in the compiler pipeline. For production code in the current toolchain, use non-generic structs.