Primitive types

API summary (generated from the Beans source by npm run coverage): 17 types · 2 instance methods.

A primitive type is the smallest kind of value Beans has. It is not made of other values. Every primitive is stored directly (unboxed) in the generated code, so it is cheap to use.

Every binding states its type. For example:

let x: int = 5
let ok: bool = true
let name: string = "beans"

The types

Type	What it holds	Size
`unit`	nothing; the empty value	0 bytes
`bool`	`true` or `false`	1 byte
`int`	64-bit signed whole number	8 bytes
`i8` `i16` `i32` `i64`	fixed-width signed whole numbers	1, 2, 4, 8 bytes
`uint`	64-bit unsigned whole number (the word type)	8 bytes
`u8` `u16` `u32` `u64`	fixed-width unsigned whole numbers	1, 2, 4, 8 bytes
`byte`	another name for `u8`	1 byte
`float`	64-bit IEEE double	8 bytes
`f32` `f64`	fixed-width floats	4, 8 bytes
`decimal`	base-10 exact number	32 bytes, align 16
`string`	immutable UTF-8 text	,

Names to know

int is the canonical form of i64. When you write int you get a signed 64-bit whole number.
float is the same as f64.
byte is the same as u8.
uint and int are the word types. Beans has no usize or isize; use int for signed word-sized numbers and uint for unsigned ones.

unit

unit is the empty value. It takes 0 bytes. A function that returns nothing returns unit. You rarely write it by hand.

bool

bool is true or false, one byte.

decimal

decimal is a base-10 exact number, for values where a binary-float rounding error would be wrong, such as money. It takes 32 bytes and aligns to 16.

decimal is only present on targets that support it. It is refused on thumbv7em-none-eabi and riscv32-unknown-none-elf. Read Numbers and decimal for the rules.

string

string is immutable UTF-8 text. Once made, it does not change. See string for every method. For a growable, changeable byte buffer, see Bytes.

Everything has methods

Even a literal number or string has methods. You can call a method right on a literal:

let a: int = (-5).abs()
let b: float = 3.7.round()
let c: Result<int> = "42".to_int()