Reading Lua code is fairly easy. The language is simple, well documented, has a official book, a package manager and plenty of resources online.

The thing is, there is not a lot of resources explaining how to read the lua source code, which is a work of art on its own and a great way to study low level software design. This project attempts to put together suggestions and material that might help you read the lua source code in a timely fashion.

The material available here is mostly the work and suggestions of other people compiled in a single place. Few free to point out if something is mentioned without a source or send merge requests with more material.

The Lua source code is written in ANSI C, a low level, statically typed programming language very common as a base for software that should live very close to the hardware.

So, the first thing you should learn is the C language. Below there are some resources you could try these:

• learn-c
• coursera c-programming
• guru99 c-programming-tutorial
• programiz c-programming
• tutorialspoint c programming
• ucam teaching C
• ravi lua5.3 bytecode reference
• ravi lua parsing and code generation

• "C Programming Absolute Beginner's Guide" by Greg Perry and Dean Mille
• "The C Programming Language" by Brain W.
• "The C Programming Language" by Kernighan
• "C Programming: A Modern Approach" by Taschenbuch

List compiled from guru99.

• A No-Frills Introduction to Lua 5.1 VM Instructions
• The Implementation of Lua 5.0

Know where to start is very important, because you need to build the knowledge in your mind to put all the pieces together. Mimemike published a suggestion in this reddit post that I'll copy below:

• lmathlib.c, lstrlib.c: get familiar with the external C API. Don't bother with the pattern matcher though. Just the easy functions.
• lapi.c: Check how the API is implemented internally. Only skim this to get a feeling for the code. Cross-reference to lua.h and luaconf.h as needed.
• lobject.h: tagged values and object representation. skim through this first. you'll want to keep a window with this file open all the time.
• lstate.h: state objects. ditto.
• lopcodes.h: bytecode instruction format and opcode definitions. easy.
• lvm.c: scroll down to luaV_execute, the main interpreter loop. see how all of the instructions are implemented. skip the details for now. reread later.
• ldo.c: calls, stacks, exceptions, coroutines. tough read.
• lstring.c: string interning. cute, huh?
• ltable.c: hash tables and arrays. tricky code.
• ltm.c: metamethod handling, reread all of lvm.c now.
• You may want to reread lapi.c now.
• ldebug.c: surprise waiting for you. abstract interpretation is used to find object names for tracebacks. does bytecode verification, too.
• lparser.c, lcode.c: recursive descent parser, targetting a register-based VM. start from chunk() and work your way through. read the expression parser and the code generator parts last.
• lgc.c: incremental garbage collector. take your time.
• Read all the other files as you see references to them. Don't let your stack get too deep though.

Happy reading! Please, share your results and suggestions!