Quick Tour

This page presents a brief tour of basic Aura syntax and concepts. Where appropriate, sections will include a link to a page containing more detailed information.

Module Definition and Imports

All Aura source files must begin with a mod declaration, and any imports should come immediately after.

mod main

import aura/io

See Modules and Imports

Program Entrypoint

Every Aura project must define exactly one main function, which is the project's entrypoint.

fn main() {
    ...
}

See Project Structure

Printing to stdout

Printing to the standard output is done with functions exported by the io standard library module

import aura/io

// Prints to stdout; does not append a newline
io.print("Hello world")

// Prints to stdout; appends a newline
io.println("Hello world")

// Assembles string and prints to stdout
io.printf("%s %d\n", "Hello world", 5)

See Standard Library and io module

Functions

Functions are defined with the fn keyword. A typical declaration would look like:

fn f(i:int) -> string {
    ...
}

See Functions

Variables

Variables can be defined with the let keyword like so:

let i: int = 5

They can also be defined with shorter syntax that omits the let keyword:

j := 5

Variables are defined as immutable by default. To define a variable as mutable, use the mut keyword:

let mut i: int = 5
mut j := 5

See Variables

Classes and Structs

Classes are defined with the class keyword, and can contain zero or more parameters and zero or more methods.

class Greeter(name: string) {
    pub fn say_hi() { ... }
}

And structs are defined with the struct keyword:

struct ApiResponse(id: string, first_name: string, last_name: string)

To create instances of classes and structs, their names are used in a function call:

greeter := Greeter("Bob")
resp := ApiResponse("1", "John", "Doe")

See Classes and Structs

Comments

Single line comments:

// Single line comment
// Goes to the end of the current line

Multi-line comments:

/* Multi-line comment
that can span multiple lines
and goes until the closing
token here -> */

See Comments

Conditional Expressions

if expressions in Aura are expressions capable of returning a value, which is done with the yield keyword.

i := if true {
    yield 1
} else {
    yield 0
}

See if expressions

Loops

for loops:

for i := 0; i < 10; i++ {
    ...
}

foreach loops:

foreach item in items {
    ...
}

while loops:

while true {
    ...
}

See Loops

Collections

Aura supports two collection types.

// Lists
l := [string]{ "Hello", "world" }

// Maps
m := map[string : int]{
    "Hello": 1,
    "World": 2,
}

See Types, Lists, and Maps

Last modified: 03 April 2024