Syntax Overview

This is a cheatsheet for Roto’s syntax. Refer to the Language Reference for the full explanation of these concepts.

Name	Example	See
Comment	# this is a comment	Comments
Unit	()	Unit type
Never type	!	Never type
Boolean	true, false	Booleans, bool
Integer	10, -100, 0	Integers
Float	10.5, -10.0, 1., 1e+10	Floating point numbers
IP address	0.0.0.0, 2001:DB8::5673:23b5, ::	IpAddr
AS number	AS1234	Asn
String	"hello, world!"	Strings, String
Format string	f"hello, world!"	String formatting
Optional values	None, Some(x)	Optional values
Anonymous record	{ x: 10, y: 20 }	Anonymous records
Named record	Foo { x: 10, y: 20 }	Named records
List	[10, 20, 30]	Lists, List[T]
Unary operator	-x	Arithmetic operators
Binary operator	x + y	Arithmetic operators
Assignment	x = 10	Local variables
Field access	x.y	Anonymous records, Named records
Function call	add(x, y)
Method call	x.add(y)
Static method call	String.append(x, y)
Let binding	let x = 10	Local variables
Function declaration	fn add(x: i32, y: i32) -> i32 { .. }	Functions
Filter-map declaration	filter foo(..) { .. }, filtermap foo(..) { .. }	Filtermap
Record declaration	record Foo { .. }	Named records
Variant type declaration	variant Foo { .. }	Variant types
If-else	if x == 1 { .. }, if x == 1 {..} else {..}	If-else
Pattern matching	match x { .. }	Match
While loop	while x < 10 { .. }	While loops
For loop	for x in e { .. }	For loops
Return	return x	Functions
Verdict	accept x, reject x	Filtermap
Import items from module	import foo.bar	Imports