LunarBasic Language Reference

This guide explains the main parts of the LunarBasic language in a simple, beginner-friendly way.

Use the topics below to learn the basics first, then explore statements, functions, and expressions as you build more advanced programs.

Start Here

Arrays - Learn what arrays are, how to declare them with Dim, and how to read and write elements with indexes.
Source Files and Comments - Learn how LunarBasic reads files, ignores blank lines, and handles apostrophe and Rem comments.
Names and Values - Learn about identifiers, numbers, strings, booleans, and the basic coordinate rules used by the runtime.
Operators and Keywords - See the punctuation, operators, and reserved words the language currently recognizes.

You can combine these core topics. For example, a custom type can include array fields:

Type Player
    Field InventorySlots(8) As Integer
End Type

Dim p As Player
p = New Player
p.InventorySlots[0] = 3

See Types and Objects for object syntax and Arrays for indexing and length helpers such as ArrayLen.

Enums - Learn how to declare enums with Enum and End Enum, assign member values, and use enum members like Direction.North.
Imports - Learn how to include other LunarBasic source files with Import.
System Functions - Discover built-in runtime functions, helpers, and constants such as Graphics, Flip, DrawText, KeyDown, and text input helpers like GetTextInput$.
Program Shape and Statements - Understand what a LunarBasic program is made of and which top-level statements are currently supported.
Types and Objects - Learn how to declare `Type` blocks, allocate objects with `New`, and access fields with `.` or `\`.
Variables, Constants, and Assignment - Learn how Const, Dim, and assignment statements are written.
Labels and Goto - Learn how labels work, where Goto is allowed, and how label scope is checked.

Control Flow - Covers If, While, Do / Loop, For, Repeat / Until, and Select / Case.
Functions, Subs, and Return - Learn how to define reusable routines and return values.

Expressions - Covers calls, member access, indexing, unary operators, binary operators, and precedence.
Errors and Current Support - A practical summary of common parser errors and what the language currently supports.

If you are just getting started, read the pages in this order: