Syntax Basics

Comments

// Single-line comment

/*
   Multi-line
   comment
*/

Variables

Immutable Bindings

let name = "Zap"
let pi = 3.14159
let active = true

Immutable bindings cannot be reassigned after declaration:

let x = 10
x = 20  // ✗ Compile error: cannot reassign immutable binding

Mutable Bindings

Use mut when you need to reassign:

let mut counter = 0
counter = counter + 1  // ✓ OK

Type Annotations

Type annotations are optional when the compiler can infer the type:

let x: Int = 42           // explicit
let y = 42                // inferred as Int
let name: String = "Zap"  // explicit

Operators

Arithmetic

Operator	Description	Example
+	Addition	3 + 4
-	Subtraction	10 - 2
*	Multiplication	6 * 7
/	Division	15 / 3
%	Remainder	10 % 3

Comparison

Operator	Description	Example
==	Equal	x == y
!=	Not equal	x != y
<	Less than	x < y
>	Greater than	x > y
<=	Less or equal	x <= y
>=	Greater or equal	x >= y

Logical

Operator	Description	Example
and	Logical AND	a and b
or	Logical OR	a or b
not	Logical NOT	not a

Expressions vs Statements

In Zap, almost everything is an expression — it produces a value:

// `if` is an expression
let status = if active { "on" } else { "off" }

// Block expressions — the last expression is the value
let result = {
    let a = 10
    let b = 20
    a + b  // evaluates to 30
}

String Interpolation

let name = "world"
print("Hello, {name}!")  // Hello, world!

Next Steps

Learn about Zap’s type system.