Introduction

LumenLang is a lightweight, stack-based scripting language built from scratch in C++20. It ships with its own compiler, its own bytecode format, and its own virtual machine — nothing is borrowed or generated by a parser toolkit.

Lumen isn’t trying to be the next production language. It’s a teaching tool disguised as one: a small, readable playground for exploring how real language toolchains work under the hood, from tokenizing source text down to executing raw bytecode instructions on a stack machine.

println 'Hello, world!'

name = ''
print 'What`s your name? '
inputStr &name

greeting = 'Hello, ' .. name .. '!'
println greeting

Hello, world!
What`s your name? Ryan
Hello, Ryan!

What this book covers

• Getting Started — building the lumen executable and running your first script.
• Language Guide — every language feature: variables, operators, strings, conditionals, labels, and routines.
• Examples — walkthroughs of the example programs shipped with the interpreter.
• Architecture — how the compiler pipeline turns .lmn source into bytecode, and how the VM executes it.
• Debugging & Tooling — the disassembler, debug symbols, and the interactive debugger.
• Reference — the opcode table and built-in function list, for when you need the exact bytes.

Project goals

Lumen exists to explore, hands-on:

• How programming languages work
• Compiler design
• Bytecode formats
• Virtual machines
• Debugging systems
• Language tooling

The goal is to keep the language approachable while implementing the same fundamental ideas used by much larger language runtimes.

Source & license

LumenLang is open source under the GPL-3.0 license. The source lives at github.com/spikest3r/LumenLang.