Builtins

Types and functions the compiler treats specially. Most are also documented in the Stdlib reference — this page is the lookup table.

Primitive types

Type	Description	Range / Notes
`Int`	Default integer type	Platform-sized signed (64-bit on most targets)
`Int8` `Int16` `Int32` `Int64`	Sized signed integers	-2^(n-1) to 2^(n-1) - 1
`UInt8` `UInt16` `UInt32` `UInt64`	Sized unsigned integers	0 to 2^n - 1
`Float`	Default floating point	Alias for `Float64`
`Float32` `Float64`	IEEE-754 floats	Single / double precision
`Bool`	Boolean	`true` or `false`
`Char`	Unicode scalar value	32-bit, valid Unicode codepoint
`String`	UTF-8 string	Heap-backed, immutable
`Pointer[T]` `RawPointer`	Pointers	FFI use only
`!`	Never type	Bottom type — see Functions → Return Types

A handful of names that look like functions but are compiler intrinsics:

Function	Purpose
`fatalError(message: String) -> !`	Abort the program with a message. Returns `!`.
`sizeof[T]() -> Int`	Static size of a type, in bytes.
`alignof[T]() -> Int`	Static alignment of a type, in bytes.

Use these sparingly. Most code shouldn't reach for sizeof; if it does, that's a sign you wanted FFI or generics.