Structuring Your Code

As scripts grow, Rugo gives you three tools for organization: structs for data types, modules for code reuse, and the Go bridge for accessing Go's standard library.

Structs: Data with Identity

Structs give hashes a name and a constructor. They're lightweight — no class hierarchies, no inheritance. Just named fields and optional methods.

struct Dog
  name
  breed
end

rex = Dog("Rex", "Labrador")
puts rex.name
puts rex.breed

rex.name = "Rexy"
puts "Renamed to: #{rex.name}"
puts type_of(rex)

Rex
Labrador
Renamed to: Rexy
Dog

Under the hood, structs are hashes with a __type__ field. The constructor creates the hash and sets each field in order. type_of() returns the struct name.

Struct Methods with Modules

Struct methods shine when combined with the module system. Define the struct and its methods in one file, then require it from another.

dog.rugo:

struct Dog
  name
  breed
end

def Dog.speak()
  return self.name + " says woof!"
end

main.rugo:

require "dog"

rex = dog.new("Rex", "Labrador")
puts rex.name
puts dog.speak(rex)

Rex
Rex says woof!

Methods use self to access the instance. Callers pass the instance as the first argument through the namespace: dog.speak(rex). The new() function is automatically created as an alias for the constructor.

Type Introspection

type_of() works on every value. Use it for runtime type checking and debugging.

puts type_of("hello")
puts type_of(42)
puts type_of(3.14)
puts type_of(true)
puts type_of(nil)
puts type_of([1, 2])
puts type_of({a: 1})

double = fn(x) x * 2 end
puts type_of(double)

String
Integer
Float
Bool
Nil
Array
Hash
Lambda

For structs, type_of() returns the struct name (Dog, User, etc.) instead of Hash. This lets you build type-aware functions when needed.

The Go Bridge

import gives you direct access to Go's standard library. Function names are automatically converted from Go's PascalCase to Rugo's snake_case.

import "strings"
import "math"
import "strconv"

puts strings.to_upper("hello rugo")
puts strings.contains("hello world", "world")
puts math.sqrt(144.0)

n = try strconv.atoi("42") or 0
puts n

HELLO RUGO
true
12
42

The bridge covers strings, strconv, math, path/filepath, sort, os, time, and math/rand/v2. Go functions that return (T, error) auto-panic on error — pair with try/or for safe handling.

Three Import Mechanisms

Use as to alias any import when namespaces collide:

use "os"
import "os" as go_os

Idiom: Prefer use modules (like str) for common operations — they're designed for Rugo's conventions. Reach for import when you need something the Rugo stdlib doesn't cover.