Programming in Lua (first edition) (2003)
lua.org
lua.org
I love how you can acquire the language easily within a very short period of time (apart from some idioms, which like in other languages take more practice). I appreciate the low number of keywords and that you have only one real way to structure data, through tables. Yet, you can use meta tables to "emulate" classes as blueprints for object creation and even inheritance, if you really need OOP, or for that matter other paradigms. In a way this reminds me of JavaScript prototypes.
As an indie game dev, Love2D really clicked. Lua is awesome as a scripting language inside a host language like C/C++/Rust, because it is simple, intuitive (both for imperative or functional styles) and rather fast.
I'm even using it as my go-to scripting language for the Linux CLI instead of Python. Python, as great as it is, feels sometimes too comprehensive for small scripts. I like to script using a language I can fully keep in my "working memory", without having to refresh my memory about some constructs/idioms. That said, I use Rust as my main statically typed language, so maybe I'm just finding excuses for my love for Lua...
I also think Lua is underrated as a possible first language. Its simplicity, readability and details like using keywords for blocks (do, end, etc) IMO make it suitable for beginners.
I guess one might argue that 1-based indexing could cause beginners to get confused when they move to another language. But maybe it's good for them to get used to the idea that things like this can be different across languages.
The main struggle people have learning to code is getting over the initial frustration hurdle where they can't actually accomplish anything yet. What they have to get them through this is excitement about their actual goals. With lua you burn too much goodwill and beginner spark on debugging string manipulation functions that don't seem important to the actual interest or goal that brought them to programming. Or figuring out how to use luarocks so you can make http requests, or regex, or whatever.
> 1-based indexing could cause beginners to get confused when they move to another language.
This is so far from the problems that beginners actually have. You should teach some programming, it's a really fascinating experience that will mess with your intuitions about how people learn this skill, and what's hard about it.
I'm quite interested in this topic, since I would like to write a good book to introduce absolute beginners into the world of programming. I have a good and encompassing knowledge about many different languages, nevertheless I lack teaching experience.
In your opinion, which languages are good candidates as a first choice and what do you think about using a Lua game framework, like for instance Love2D to teach programming (instead of raw standalone Lua)? The idea being that instead of clunky low level awkwardness, like string manipulation, students would instead see geometrical shapes moving on a screen with just a bunch of simple and imperative statements. Would that provide a better motivation?
But when people decide to learn programming now, they usually have a goal in mind so the best language is the one that lets them keep that objective in focus as they learn. Not necessarily do it most easily: love is good because while making a game with it is a huge undertaking for a novice, they can see the whole time that game-making is what they're building up to.
But for example I've seen rank beginners get really fascinated with data visualization, or interacting with their local government's API, or text generation, or audio stuff. All things that are going to be out of reach for a novice in lua. And a lot of people will show up saying they want to make games, but it's because video games are the one programming artifact they have positive experiences with. Once they start to see the broader possibilities other interests develop.
Anyway I have had a lot of success introducing programming with roblox scripting. It adds a lot of the "missing" lua library features and the script editor is a decent basic IDE that simplifies tooling, another huge pain point for novices.
For non-game focused beginners I've had the best results in ruby. Python works as well once you get going but the whitespace is a frustrating time sink in a classroom environment. In these the strength is being able to grab a library for any API they'd want to work with, and build something that feels like an actual useful tool to them.
I've had some success introducing programming in Lua to kids (ages 7-12) by way of the OpenComputers Minecraft mod. They were all already into playing modded Minecraft, and getting in-world feedback from running various commands (turning on/off redstone signals, moving around blocks, attacking monsters, etc.) meant that the "boring" time between "hey, let me show you how to program" and something exciting happening was <5 minutes. Beyond Minecraft-specific libraries, the computers in the mod also come with a HTTP client library, an editor and a shell that directly runs Lua scripts.
My friend was like "no way. im gonna start him with something simple like html."
Within seconds he realized he had to explain what paths were, and his brother struggled so much with them. My friend took for granted what he had already spent time learning. He was unable to guess what would be difficult to understand without priors.
Walled gardens like Processing seem to be better for education.
Downloading archives with a web browser and extracting them and just doing manual file management is vastly preferable in such an environment. That is a vastly simpler process which is impossible to break, and odds are the student will already be familiar with most of the process.
Managing archives is not easier in my experience, for the format I teach. Students are not necessarily using the same packages, not all on the same OS, and familiarity with manually managing files cannot be assumed. Probably the majority of middle schoolers I teach do not have that skill coming into my class, high school maybe 50/50.
The creator of Lua once visited my university, he told us about the 1-indexing (it looked like this is the thing that everybody asks him). Lua was created in a time that 0-indexed languages wasn't so dominant over the 1-based languages.
Lua is older than Java and JS, and a few years newer than Perl and Python. Before those, as far as I remember about more popular languages: C and C++ are 0-indexed; COBOL, MATLAB and FORTRAN are 1-indexed; Pascal can be 0 or 1 indexed, but its for loop is better suited for 1-indexed.
This way, there wasn't a strong bias to use 0-index in a new language as we have today, they could use what made more sense. Since it was created for engineers used to math notation (sum, products and matrices generally are 1-indexed) and without background in programming, they have chosen to start in 1.
*However*, about using Lua for studying algorithms and data structures, some books use 1-indexed arrays in their pseudocode, notably CLRS' Introduction to Algorithms. When I was studying algorithm analysis using CLRS I used Lua to implement them. I still prefer 0-indexed languages, though.
Indeed the 1-based indexing, which often generates heated discussions, could be a source of confusion later on. However, like you mentioned, it can also prompt the beginner to quickly understand the languages are just tools, which have slightly different ways to be used, depending on what they're trying to solve.
In fact, this 1-based indexing is by convention (although everyone uses it), once again showing how flexible and "hackable" Lua is.
> array = {"A", "B", "C"}
> array[1]
A
Types/type checking would also be nice. Luau does seem to offer some level of static typing, but it isn't used by a whole lot that I've seen.
That said, I think a lot of people are also glad it doesn't include much, because one of the biggest draws of Lua is that it's extremely compact and embeddable. And I do understand that, too. I remain a huge fan of Love2d even though I haven't actually released anything with it.
This is because of the design choice of Lua. Authors do not ensure retro compatibility and this is why there were so much outdated external libraries when Lua 5.2 came in. Even the most popular LuaSocket wasn't updated in years.
In fact, Lua is definitely not intended to be used as a drop-in replacement to Python, Ruby or Perl because of that. It's entirely designed to be embedded as-in in your host-program and that you must provide your own extensions.
However, keep in mind that:
a. you will need to carry the documentation of Lua you've included b. if you plan to upgrade the bundled Lua you will have to polyfill all changes to avoid breaking your userbase code (and this is a real PITA) c. you'll end up with lots of `#ifdef` in your code
I think that are few reasons why Lua stalled that much (without even mentioning all uncommon features `~=`, `goto`/`break` but no `continue`, array start at 1, too minimalist unicode support, ...). I've been including Lua 5.1, 5.2 and 5.3 in one of my projects before I eventually stopped to backport compatibility layers. I also gave up on my LuaSDL repository because it was too much of headaches. It's a shame because I loved this language a lot.
Perhaps it could, but it should?
Let me explain. Take the example of JavaScript, which was kinda similar to Lua when it was conceived: both were simple languages, targeted to solve specific problems, waiving more complex features and delegating many things to their users.
Example: early JS and Lua don't have OO, but they have the tables (Lua) and objects (JS) which are hash tables with some syntax sugar to look like POO languages if you needed. Then, the user is responsible to handle this in a sane way, which should not be big deal for the scenario that those languages were created.
JS, however, has grown outside its original purpose. Somehow it became a server language, and somehow it became a monster. TypeScript, CoffeeScript, ClojureScript and others were created to delegate back stuff to the language. Lua, however, is still doing well its job in its simplicity.
As a game engine guy, I’ve been setting up Lua to be used by semi-technical game designers. I know I’m going to have to help them debug some crazy script months from now, so I want to carefully prescribe the APIs they get to play with from the beginning. Ex: No raw file system access! Only load assets through the asset system.
Lua shines when it is embedded in a larger program, giving high-level commands. There have been plenty of projects trying to build full applications in Lua. But, that’s really fighting against its design.
Lua on the other hand is all over the place. Wireshark dissectors, OpenResty, game engines, and tons more.
That said, it seems like almost everyone is still embedding Lua 5.1 or forks of it like LuaJIT, and I think a lot of game engine people want slightly different things out of Lua than what it offers, hence offshoots like Luau, GameMonkey script, and Squirrel lang. Maybe it's good that Lua doesn't try to be all things to all people, since it has broad applicability, but it does feel, at least to me, like things could be better. For example, at least having a syntax for types that could be checked externally, like Python. The core shouldn't be bloated up with a module system and package manager, but a CLI tool with that functionality certainly would be nice, could probably be written in Lua. And I do understand why people don't want an all-encompassing standard library, but not having bitwise operators in the language or standard library can be a bit of a drag. That's just my thoughts on the matter, anyway.
C# took about 2h to do this acceptably. Javascript took 4h or so and I'm still not happy with it. Too many warts and odd ways of accessing arrays etc...
Lua took 30 minutes and it just worked perfectly. There was nothing left to do. it's just so simple.
I love that about it.
But as a Linux CLI lang, or for simple one-off scripts... Python is better. Scripts (and also competitive programming) favour languages capable of compact solutions and universal stdlib. Lua, because is has no stdlib to speak of and a limited amount of syntax sugar. It is just so much less useful for these purposes.
As for competitive flavours of programming... I recently gave it a go for Advent of Code 2024.
My impressions: https://www.reddit.com/r/adventofcode/comments/1hvnou1/2024_...
My repo: https://github.com/vkazanov/advent-of-code-2024?tab=readme-o...
TL;DR Python is better here.
ie. You have a big application that has a configurable feature and you also need that configurable feature to be super flexible since the amount of possible variations on that feature is so large that it's not worth maintaining it in the "main" language. An example could be say, an enemy AI decision script in a turn based RPG. While you can hardcore the decisions into the language itself, it doesn't make it easy to modify (especially if you want to iteratively test it, since each iteration needs a recompilation of the entire program).
That's where LUA shines - instead you just put it in a LUA file and it's dynamically loaded and interpreted when it's needed, allowing you to rapidly modify it without needing to recompile the entire game.
Python is amazing for scripts that are also software in their own right, LUA is amazing for snippets (so a layer smaller than scripts), since on that level, none of it's shortcomings are a problem. The C interop and sandbox also makes it fairly easy to set up a DSL/importable module that runs your "main" language if that's what you need as well.
It's the standard library that forms the "grammar" of the language and is often the hardest part to incorporate.
The most recent edition of this book is from 2016. Surely time for a new edition.
I totally resonate with your comment about the language not getting in your way. I use all sorts of languages for different kinds of applications for many years and only recently I started creating games.
Whereas in other domains I appreciate complex languages that address necessarily complex tasks, in game development, while the game as a whole is a complex system, you often are handling simpler tasks and mostly thinking about algorithms. At least in my experience tackling these algorithms requires mostly mathematical calculations and for that, you definitely want the language to stay out of your way.
In game dev no matter if you pick an imperative or functional approach, you really need to use all your brain power on your problem domain. Language complexities are often distractions that aren't super useful, since like I already said, the task at hand is mainly algorithmic in nature.
My experience is the same as you describe: I want to think about algorithms, state machine, system structure, design, the... game. Rather than the language semantics, quirks, or fancy features. 100% agree with you.
I'm not sure there is a fifth edition (for Lua 5.4) but the manual/reference + fourth edition seems good enough for at least my usage: https://www.lua.org/manual/5.4/manual.html
https://www.lua.org/pil/20.1.html
It is not as powerful as regexp, but it's a huge step up for string munging over raw find/substr.
It is lightweight when not in use and integrates perfectly with the core C codebase.
If I had to pick one single thing that has had the most impact in our game over the 25 years we have been around it would be moving all of our in-game scripting to Lua.
https://www.freelists.org/post/luajit/Port-bitop-to-53,1
The biggest issue certainly is the addition of integer types.
edit: sorry I should have searched, Luajit only supports up to Lua 5.1
So the spectrum is from newer language and slower to older language and faster. If performance is an issue the cost of the newer language features could be that more of the application code has to be written in C++ instead of Lua - in that context the Lua language shouldn't be considered independent of the host language. Performance matters to me so increase in C++ code would not be worth the newer language features. Using Rust instead of C++ as the host language might change the landscape again since Rust is so much more ergonomic than C++.
> If you find this online version useful, please consider buying a copy of the current edition. This helps to support the Lua project.
And then after 5.1, basically every minor version (5.2, 5.3, so on) have major changes between them, from what I recall.
I remember some undocumented edge cases in string match patterns breaking between 5.1 and 5.2. Imagine Python changing how regexes worked between two minor releases.
"Defence"? Seems like the correct answer and a fact, Lua doesn't do semver, so when there are major changes between 5.3 and 5.4, it's not illogical or actually breaking semver, as they don't follow it.
Plenty of projects don't follow semver, and that's perfectly fine.
Really good teacher.
Back in 2019, a group of students was organizing a week of computer science in my university (IME-USP) and they were collecting suggestions. I suggest to bring Roberto to talk something about Lua without hope that the suggestion would be accepted and that he would come. And when I checked the schedule I saw that he would present in that week.
Not only that, the day before his presentation the professors of our department arranged an informal conversation with him, and I was there. Lua is probably one of software projects that I admire the most due to it has been created to solve a problem and that solves it well, without trying to be more than that. Seeing Roberto speaking about it so close was really a memorable moment.
(Submitted title was "Lua Programming in Lua (first edition) (2003)")