Built-in types

The following built-in types can be passed as arguments/returned by Rust methods:

Rust type	UDL type	Notes
bool	boolean
u8/i8..u64/i64	u8/i8..u64/i64
f32	float
f64	double
String	string
Vec<u8>	bytes	Different from sequence<u8> only in foreign type mappings
SystemTime	timestamp	Precision may be lost when converting to Python and Swift types
Duration	duration	Precision may be lost when converting to Python and Swift types
&T	[ByRef] T	This works for &str and &[T]
Option<T>	T?
Vec<T>	sequence<T>
HashMap<K, V>	record<K, T>
()	void	Empty return
Result<T, E>	N/A	See Errors section

And of course you can use your own types, which is covered in the following sections.