Type System

Cyrus features a strong and expressive type system. The compiler performs implicit type conversions when it is safe, and requires explicit casts when conversions could be unsafe or lossy.

Safe Implicit Casting

If a type can be safely converted to another type without losing information, Cyrus will perform the conversion automatically.

var a: int32 = 42;
var b: int64 = a; // implicit cast from int32 to int64

int32 (32-bit signed integer) can always fit into int64 (64-bit signed integer).
The compiler handles this implicitly, so no special syntax is required.

Unsafe / Explicit Casting

If a conversion could be unsafe, the compiler requires an explicit cast using the cast keyword.

var u: uint32 = 10;
var i: int64 = @cast(int64, u); // Explicit unsafe cast from uint32 to int64.

Basic Types

Cyrus provides a set of built-in types for numbers, characters, booleans, and special-purpose values. These are the fundamental building blocks of your programs.

Type	Category	Bit Width	Signedness
int	Signed Integer (default)	32	Signed
int8	Signed Integer	8	Signed
int16	Signed Integer	16	Signed
int32	Signed Integer	32	Signed
int64	Signed Integer	64	Signed
int128	Signed Integer	128	Signed
uint	Unsigned Integer (default)	32	Unsigned
uint8	Unsigned Integer	8	Unsigned
uint16	Unsigned Integer	16	Unsigned
uint32	Unsigned Integer	32	Unsigned
uint64	Unsigned Integer	64	Unsigned
uint128	Unsigned Integer	128	Unsigned
intptr	Pointer-sized Integer	Pointer width	Signed
uintptr	Pointer-sized Integer	Pointer width	Unsigned
usize	Size / Index Type	Pointer width	Unsigned
isize	Size / Index Type	Pointer width	Signed

Floating-Point Types

Type	Description	Precision
float16	16-bit floating-point number (half precision)	~3 decimal digits
float32	32-bit floating-point number (single precision)	~7 decimal digits
float64	64-bit floating-point number (double precision)	~15–16 decimal digits
float128	128-bit floating-point number (quadruple precision)	~34 decimal digits

Character and Boolean Types

Type	Description	Notes
char	A single character unit (one code unit; multi-byte Unicode not allowed in `'...'`).	Unsigned; Represents ASCII/byte chars only
bool	Boolean values, either `true` or `false`.	1-bit storage (typically padded to 8 bits)

Special Types

Type	Description	Notes
void	Represents no value, commonly used for functions that do not return anything.	Return type only

Type Aliases

You can create aliases for existing types. The compiler automatically expands these whenever the alias is used.

type rune = uint32;
type my_int = int16;

pub fn main() {
  const x: rune = 10;
  const y: my_int = 20;
}

Note: Type aliases cannot be declared locally. Their scope and declaration rules will be covered in more detail later in these documents.

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Type System
- Safe Implicit Casting
- Unsafe / Explicit Casting
Basic Types