Lang

The lang module offers a way to create user-defined structures and enumerations.

A structure can pack together variables and functions, which allows object-oriented programming.

An enumeration is a set of names bounds to constant numerical values.

All the given examples assume the following imports:

let lang = import('std/lang');
let io = import('std/io');

Functions

• struct
• enum

Struct

lang.struct(field = value, ...) -> type

Creates a new structure type type holding a set of fields. The given values are used to infer the type of each field and as default values during construction. The returned type can be used to instantiate objects of this type.

Adding member functions to a type is done with the let func in type = fn(args) {}; construct, with func being the function's name. Inside the function, variables and functions belonging to the type can be accessed using the self keyword.

Example:

let player_t = lang.struct(name = "John", class = "Mage", health = 100, attack = 10);

# str is used by print functions to print the content of an object
let str in player_t = fn() {
    let desc = '';
    desc += "name: " + self.name.str();
    desc += ", class: " + self.class.str();
    desc += ", health: " + self.health.str();
    desc += ", attack: " + self.attack.str();
    return desc;
};

let take_damage in player_t = fn(damage) {
    io.println('Taking ', damage, ' damage');
    self.health -= damage;
    return self;
};

let player = player_t("Bob", attack = 20);  # Positional and named arguments allowed
io.println(player);                         # Calls player.str()
player.take_damage(30).take_damage(10);     # Possible thanks to 'return self'
io.println(player);

Gives the output:

name: Bob, class: Mage, health: 100, attack: 20
Taking 30 damage
Taking 10 damage
name: Bob, class: Mage, health: 60, attack: 20

Enum

lang.enum(.name1, .name2 = value, ...) -> type

Creates a new enumeration with the given names and optionally given values. Names must be prefixed with a dot.

Example:

let class = lang.enum(.Mage, .Warrior, .Mecromancer, .Unknown = -1);
let player_t = lang.struct(name = "John", class = class.Unknown, health = 100, attack = 10);

let str in player_t = fn() {
    let desc = '';
    desc += "name: " + self.name.str();
    desc += ", class: " + self.class.str();
    desc += ", health: " + self.health.str();
    desc += ", attack: " + self.attack.str();
    return desc;
};

io.println(player_t("Bob", class.Mage));
io.println(player_t("Josh"));

Gives the output:

name: Bob, class: 0, health: 100, attack: 10
name: Josh, class: -1, health: 100, attack: 10