Reference

A sheet to look things up at a glance. Each section points to the page that covers it in full.

Reserved words

They can't be the names of variables, functions, classes or parameters:

and	break	case	catch	class	const
continue	def	default	div	do	elfor
else	elsif	end	enum	exit	false
fn	for	foreach	func	if	import
in	mod	nil	not	off	on
operator	or	private	ref	repeat	return
struct	super	switch	then	this	true
try	type	until	use	var	while

do, repeat and ref are reserved, but in 0.9.7 they aren't used for anything: while and until don't take do, and ref gives an error when compiling.

Words	What for	Where
var, const, enum	Variables, constants and enumerations	Variables and constants
if, then, elsif, else, switch, case, default	Choosing what runs	Control structures
for, elfor, foreach, in, while, until, break, continue	Loops	Control structures
end	Closing a block	Basic syntax
func, return, fn	Functions and lambdas	Functions
class, def, this, super, private, operator	Classes and objects	Classes and objects
struct	Data structures	Structs
try, catch, exit	Errors and leaving the program	Errors and exceptions
use, import	Modules and other files	Programs in several files
and, or, not, div, mod	Operators	Operators
true, false, on, off, nil	Values	Data types
type	The type of a value	type

Operators

Operators	What they do
+, -, *, /	Addition, subtraction, multiplication and division. / always gives a decimal: 5 / 2 is 2.5.
div, mod, %	Integer division and remainder: 5 div 2 is 2, and 5 mod 2 and 5 % 2 are 1.
++, --	Add or subtract one to a variable: x++.
==, !=, <, <=, >, >=	Compare two values.
and, or, not, !	Logical. ! is the same as not.
&, |, ^, ~, <<, >>	Bitwise. With two booleans, ^ is the exclusive or: true ^ false is true.
? :	Conditional: a > b ? a : b.
=, +=, -=, *=, /=, %=	Assignment.

In JARU, and and or have the same precedence, and not is worked out before comparisons: use parentheses when you mix them. The order of all of them is in Operator precedence, and each one, with examples, in Operators.

Types

Type	Written as	type() gives
Boolean	true, false, on, off	tBool
No value	nil	tNil
Integer, 32-bit signed	42, -7, 0x1F	tInteger
Decimal, 64-bit	3.14, .5, 1e3	tFloat
String	"hello", 'hello'	tString
List	[1, 2, 3]	tList
Map	{"x": 1, "y": 2}	tMap
Array	{1, 2, 3}	tArray
Function and lambda	func, fn	tFunction
Class and instance	class, Player()	tClass, tInstance

The details are in Data types. String methods are in Strings, and those of lists, maps and arrays in Lists, maps and arrays.

Standard library

Functions that don't need use:

For	Functions
The console	print, println, readLine, cls, ink, paper
Time	pause, clock, time
Converting and knowing the type	chr, int, float, type
Random numbers	randomize, random
Arithmetic	abs, round, sqrt, vlenght
How long something is	len
Colors	rgb
The system and memory	memUse, memFree, platform, vmerror
Base64	encode64, decode64

Constants

The compiler knows them without use:

Constants	What for
HW_ESP32, HW_ESP32S3, HW_WIN32, HW_WEB, HW_ESP32P4, HW_ESP32S31	What platform() returns
tBool, tInteger, tFloat, tString, tList, tMap…	What type() returns
ERR_UNKNOWN … ERR_TIME_OUT	The errors: see Errors and exceptions
LOW, HIGH	The levels of a pin: see GPIO
PI, SQRT2	π and √2: see Math

The full list, with their values, is in Constants.

Modules

They're brought in with use, as in use Display. How they're used, in Modules.

Module	What for
Display	Opening the screen or the window, its size and its background, and the game's pace
Draw	Drawing points, lines, rectangles, circles, text, images and tilemaps
Bitmap	Loading BMP images and working with them
Sprite	Sprites with animation, collisions and physics
GridMap	2D grids: tilemaps, collisions with the map and pathfinding
Scene	The scene: its sprites, the camera, the physics and the map
Sound	Synthesised sounds, PCM samples and music
Input	The keyboard, the buttons and the gamepad, as game actions
GPIO	Input and output pins, PWM and interrupts
I2C	Sensors and other devices connected over I2C
LED	Strips and matrices of WS2812 colour LEDs
Power	Putting the board to sleep to save power, and waking it up
MQTT	Publishing and receiving MQTT messages
Http	HTTP requests to APIs and web services
File	Files and folders, in the flash, on the SD card or on the PC
Bytes	Byte blocks for binary data
JSON	Reading and writing JSON
Timer	Calling a function after some time, once or every so often
Math	Mathematical functions and constants
GC	The garbage collector, which frees the memory that's no longer used

Resources

• The JARU website
• GitHub
• Contact: info@jarulang.com