Data Types¶

Arx uses explicit type annotations for variables, function parameters, and function return types.

Type Annotations¶

Function parameters must always be typed.
Function return type is declared with -> type and is always required, including -> none.
Variable declarations must include an explicit type with var name: type.

```
title: Typed function signature
summary: Demonstrates required parameter annotations.
```
fn add(a: i32, b: i32) -> i32:
  ```
  title: add
  summary: Returns a + b.
  ```
  return a + b

Common Annotation Forms¶

fn summarize(name: str, values: list[i32]) -> none:
  var count: i32 = 0
  return

Common places where types appear:

function parameters: fn add(a: i32, b: i32) -> i32:
function return types: fn test_add() -> none:
variable declarations: var total: i32 = 0
generic-style element annotations: list[i32]

Built-in Type Reference¶

For the catalog of built-in types, aliases, and examples, see Built-in Types.

That page covers:

numeric types and aliases
none as the unit type and value
string, character, and temporal types
lists and current limitations
the cast(value, type) helper