Modules

Importing modules

Use summon to import another .rune file:

summon "math_utils.rune";
summon "models/hero.rune";

When a file is summoned, its entire contents are executed in the current scope. All Rituals, Guilds, Realms, and variables defined in the summoned file become available.

How it works

Given two files:

utils.rune:

Ritual double(Countstone x) begins
    returneth x * 2;
end of Ritual

Ritual clamp(Countstone val, Countstone low, Countstone high) begins
    Quest begins when (val < low)
        returneth low;
    elsewise when (val > high)
        returneth high;
    end of Quest
    returneth val;
end of Ritual

main.rune:

summon "utils.rune";

Countstone result is double(21);
Chant(result);  // 42

Countstone clamped is clamp(150, 0, 100);
Chant(clamped);  // 100

Run with:

runelang main.rune

File resolution

Paths are resolved relative to the file doing the importing:

project/
  main.rune            <- summon "lib/helpers.rune"
  lib/
    helpers.rune        <- summon "utils.rune"  (resolves to lib/utils.rune)
    utils.rune

Deduplication

If the same file is summoned multiple times (directly or transitively), it’s only executed once. This prevents duplicate definitions and circular import issues.

// both of these import utils.rune, but it only runs once
summon "utils.rune";
summon "utils.rune";  // no-op

Organizing a project

A typical RuneLang project might look like:

my_game/
  main.rune
  models/
    hero.rune
    monster.rune
    item.rune
  utils/
    math.rune
    format.rune
  data/
    levels.rune

main.rune:

summon "models/hero.rune";
summon "models/monster.rune";
summon "models/item.rune";
summon "utils/math.rune";

Familiar player is summon Hero("Thorin", 100, 30);
// ...

Note: summon has two uses in RuneLang:

1. summon "file.rune"; — imports a module (file path as a string)
2. summon GuildName(args) — creates a Guild instance (constructor call)

The parser distinguishes between these by checking whether the argument is a string literal (module import) or an identifier (Guild instantiation).