Option Type

Option[T] represents a value that may or may not exist. It replaces null in other languages.

Definition

type Option[T] =
    | Some(T)
    | None

Creating Options

let some_value: Option[i32] = Some(42)
let no_value: Option[i32] = None

Working with Options

Pattern Matching

fn describe(opt: Option[i32]) -> string {
    var result: string = ""
    match opt {
        Some(n) => { result = "Has value: " + to_string(n) }
        None => { result = "Empty" }
    }
    return result
}

Null Coalesce Operator

Use ?? to provide a default value:

let value: i32 = maybe_value ?? 0
let name: string = maybe_name ?? "Anonymous"

Standard Library Functions

The std.option module provides utilities for working with options:

import std.option

// Check if a value exists
let has_value: bool = std.option.is_some(opt)
let is_empty: bool = std.option.is_none(opt)

See Standard Library Overview for more details.