Structs

Structs

Table of Contents

• Syntax
• Fields and Defaults
• Construction Rules
• Field Access
• Notes

Table of Contents

• Syntax
• Fields and Defaults
• Construction Rules
• Field Access
• Notes

Structs are lightweight, immutable-by-definition types with fixed fields and positional construction. They are ideal for small data carriers when you don’t need methods or inheritance.

Syntax

struct Point { x, y = 0 }

let p = Point(3);      // x=3, y=0
let q = Point(1, 2);   // x=1, y=2

Fields and Defaults

• Fields are declared by name.
• Defaults are optional and use =.
• Missing arguments use defaults; if no default is given, the field becomes nil.

struct Person { name, age = 0 }
let a = Person("Ada");
let b = Person("Bob", 42);

Construction Rules

• Structs are constructed by calling the struct name like a function.
• Arguments are positional (no named arguments).
• Too many arguments is a runtime error.

// Error: too many arguments
// let p = Point(1, 2, 3);

Field Access

Struct instances are maps, so field access uses dot syntax:

let p = Point(5, 7);
print(p.x, p.y);

Fields are mutable (you can reassign):

p.x = 10;

Notes

• Structs do not support methods or inheritance.
• Default expressions are evaluated when the struct is declared.
• Struct instances expose an internal __struct link to their defining struct map.