Variables & Data Types

Aegis allows you to store data using mutable variables or immutable constants.

It is a dynamically typed language by default. This means you do not need to specify the type of a variable when you declare it, and a variable can hold values of different types throughout its life (unless you use Gradual Typing).

Mutable Variable

Use the var keyword when the value needs to change during the execution of the program.

var username = "Admin"
var score = 100
var is_active = true

Reassignment

You can change the value of a variable at any time:

var data = 42
print data // 42

data = "Changed to string"
print data // Changed to string

Immutable Constants (const)

Use const for values that must remain the same throughout the entire scope (e.g., configuration, math constants). This provides safety and clarifies intent.

const PI = 3.14159
const MAX_RETRIES = 5

// Using the value works fine
var area = PI * 10 * 10

Safety Check

Constants are protected at Compile Time. If you try to reassign a constant, Aegis will raise an error and refuse to run the script.

const URL = "https://google.com"

// This causes a panic/crash at compile time:
URL = "https://bing.com" 

Tip: It is considered good practice to name constants using UPPER_SNAKE_CASE (e.g., MAX_SPEED), although Aegis does not enforce it.

Primitive Types

Aegis supports the following primitive data types:

Note: Lists and Dictionaries are complex types and are covered in the Data Structures section.

String Interpolation

You can inject variables directly into strings using the ${} syntax. This converts the value to a string automatically.

var name = "Aegis"
var version = 0.2

print "Welcome to ${name} version ${version}!"
// Output: Welcome to Aegis version 0.2!

Compound Assignment

Aegis provides shorthand operators to modify the value of a variable based on its current value. This avoids repeating the variable name.

Examples

var score = 10
score += 5  // score is now 15
score *= 2  // score is now 30

Increment & Decrement

To quickly add or subtract 1 from a number, you can use the increment (++) and decrement (--) operators.

var i = 0
i++ // i is now 1
i++ // i is now 2
i-- // i is now 1

These operators also work on object properties:

player.hp -= 10
player.level++