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Types & Structs

Structs

struct Point {
    x: Float,
    y: Float,
}

let origin = Point { x: 0.0, y: 0.0 };

Enums

enum Direction {
    North,
    South,
    East,
    West,
}

enum Option<T> {
    Some(T),
    None,
}

Interfaces

Interfaces define shared behavior:

interface Serializable {
    fn serialize(&self) -> String;
    fn deserialize(data: String) -> Self;
}

impl Serializable for Point {
    fn serialize(&self) -> String {
        return "{{self.x}},{{self.y}}";
    }

    fn deserialize(data: String) -> Self {
        let parts = data.split(",");
        return Point {
            x: Float.parse(parts[0]),
            y: Float.parse(parts[1]),
        };
    }
}

Generics

fn first<T>(items: Array<T>) -> Option<T> {
    if items.length == 0 {
        return Option.None;
    }
    return Option.Some(items[0]);
}

Type Aliases

type UserId = String;
type Matrix = Array<Array<Float>>;

Wrapper Types

Sailfin provides special wrapper types for safety:

let email: PII<String> = PII.wrap("user@example.com");
let api_key: Secret<String> = Secret.wrap("sk-...");
let handle: Affine<FileHandle> = open("data.txt");  // May be dropped, not copied
let token: Linear<AuthToken> = mint_token();          // Must be consumed exactly once

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