Variables & Types

let and var

let declares an immutable binding. var declares a mutable one.

let x = 42          // can't reassign
var count = 0       // can reassign
count = count + 1

let name = "Milo"   // type inference works

Under the hood, let maps to an SSA register and var maps to a stack allocation. What you write is what LLVM sees.

Primitive types

Type	Description
i8, i16, i32, i64	Signed integers
u8, u16, u32, u64	Unsigned integers
f32, f64	Floating-point
bool	true / false
int	Alias for i64
float	Alias for f64
byte	Alias for u8

Number literals

let dec: i32 = 1_000_000      // underscores for readability
let hex: i32 = 0xFF            // hexadecimal
let bin: i32 = 0b1010_1010     // binary

Character literals

Character literals produce u8 values:

let ch: u8 = 'A'       // 65
let newline = '\n'

Type casts

Use as to convert between numeric types:

let big: i64 = 42
let small = big as i32

let f: f64 = 3.7
let n = f as i32       // truncates to 3

Bitwise operators

Integer-only. C-style precedence.

let mask: i32 = 0xFF & 0x0F    // 15
let shifted = mask << 2
let negated = ~mask

Control flow

if x > 0 {
    print("positive")
} else if x == 0 {
    print("zero")
} else {
    print("negative")
}

var i: i32 = 0
while i < 10 {
    if i == 5 { break }
    i = i + 1
}

Next: Functions →