[QuaternionsBhop]

After 10 years and many projects, the greatest with 40k lines of code including a time-of-intersection-solving single body physics system, I have come to know how to use Lua for my purposes. Even so, from the moment I started watching Rust hype videos on YouTube, I knew I would eventually be converted into a Rust fanatic. At the end of a 2 year project to rewrite my Lua game with a new physics system, I felt it was a good time to learn Rust (and rewrite the game again in Rust). So far I have spent 6 months in Rust and my old tool looks like a toy. How did I ever live without iterators, algebraic data types, the safety of a strong type system, and especially separate types for arrays and hashmaps for god sakes?

Lua makes the scope of learning programming smaller compared to other languages, so it is probably fair to say that it is a good language to learn programming with. However, knowing the details of heap vs stack, array vs hashmap, and explaining that to someone learning programming for the first time within a language that attempts to hide those details is frustrating. I can't see the smaller picture and view a table simply as a thing that you get and set values from, I can't see the weak types as anything more than an annoying source of bugs at runtime, and I crave the borrow checker which saves me from myself.

My 10 years of Lua set me up to appreciate Rust's fantastic design choices, and I'm having a great time in Rust land. I wish to remain in Rust land but my finances demand me to use my Lua skills at least a little while longer. End of ramble

[_ugfj]

The fanaticism of Rust programmers are well known and off putting. Why, one of them just posted about it into a Lua thread. It couldn't be less relevant. Much as I don't have a hard choice between picking assembly and PHP for a task, Rust and Lua are just not in the same problem space.

[umvi]

I read his post less as Rust fanaticism and more someone who has learned their first programming language isn't perfect - strong types? iterators? These are all things that are present in many languages, it just sounds like Lua is lacking them and he is discovering some of the cool features of other languages.

[nmz]

But lua isn't lacking them, <for in do> is for generators, and if you want iterators you can make those as well.

[bmitc]

Do you know if Lua supports type annotations or gradual typing? I use those heavily when using dynamically typed languages.

[nmz]

It does not. The most viable solution is transpilation, teal is the most recent candidate.

You can have a hack of sorts using a schema and tables as in

local schema = { a = "number", b="string" } -- key = "type" local data, link = {a=4, b="default value"}, {} -- link -> data, link itself is always empty local tbl = setmetatable(link, { __index = data , __newindex = function (t,k,v) if schema[k] and type(v)==schema[k] then data[k] = v return true end error"type does not match schema" end })

tbl.b = 5 -- this will error because its the wrong type

There are certain solutions you can do with functions, lsp is also really good at telling you when you went wrong.

[QuaternionsBhop]

No, Lua does not, but check out Roblox's Luau which is a gradually typed extension of Lua.

[nmz]

I'd recommend teal because luau is not really lua.

[brink]

People complaining about Rust evangelism is about as much of a trope as the Rust evangelism.

Though I would rather spend my days listening to people talk about what they love rather than what they hate, so your response is more tiresome than the person you're replying to.

[pfg_]

I think they are. Rust is a general purpose programming language, and Lua is a language specifically designed to be embeddable. But that means if you're making a project that embeds Lua, like Factorio for example, you have the choice of what language you write the code in. The choice is whether to write a function as native or to write it in Lua, and that choice might not be super clear unless someone else already made that choice for you.

This is completely different than assembly vs PHP. Assembly is a 'don't use it unless you have to' programming language, while PHP is a programming language designed for website building. You wouldn't use assembly to make a website because there are no frameworks for it and you'll scream and cry. You wouldn't use PHP to write the entrypoint to your operating system because PHP can't do that.

Rust and Lua are a lot closer together than PHP and assembly and it often would be reasonable to compare these languages for the same problems. It's not relevant at all to the blog post though because the engine they're using is built for Lua, and it's not really up to them unless they want to work against the engine and try to use a different language.

[hu3]

> Rust and Lua are a lot closer together than PHP and assembly.

Perhaps for some definition of closer, but they are very far away still.

Like opposite-ends-of-many-spectra far away.

[saagarjha]

Amusingly I’ve gotten more job offers for web software written in assembly than PHP

[IshKebab]

I think he was just offering the perspective of someone else that has also written a lot of Lua.

> The fanaticism of Rust programmers...

Honestly the endless criticism of Rust "fanatics" is far more tedious than anything Rust developers say. Rust is a fantastic language. Do you expect people not to talk about it?

[QuaternionsBhop]

> I think he was just offering the perspective of someone else that has also written a lot of Lua.

This is what I was going for, but I am a recent Rust convert and cannot help myself from gushing over Rust. Sorry!

[chx]

> Honestly the endless criticism of Rust "fanatics" is far more tedious than anything Rust developers say.

We can agree to disagree. I am sick and tired of Rust people screaming at the top of the lungs in every possible place about how their language is great and want to rewrite everything in it.

So yes I expect people not to praise Rust in a Lua thread, it's completely off topic.

[bmitc]

Rust's ecosystem is also very sporadic. It seems everyone jumped on board in the gold rush (and still do), reinvent the wheel in some package to lay claim, and then abandon it when its 70% there once they get bored and/or realize rust doesn't magically solve programming.

[hu3]

There was an article related to that recently:

https://loglog.games/blog/leaving-rust-gamedev/#gui-situatio...

[IshKebab]

That isn't really about people abandoning GUI development. Most of the big Rust GUI efforts are still going. The problem with Rust GUI libraries is that Rust isn't really old enough to have mature ones yet.

[gitaarik]

People also talk about other languages in this thread. It rather seems to me that you are just a hater.

[akira2501]

> knowing the details of heap vs stack, array vs hashmap, and explaining that to someone learning programming for the first time within a language that attempts to hide those details is frustrating

These are implementation artifacts. Knowing how to program does not require any knowledge of them.

> and my old tool looks like a toy.

The great thing about toys is they are very easy to put down for a while and then pick back up again later with very little effort.

[idoubtit]

> The great thing about toys is they are very easy to put down for a while and then pick back up again later with very little effort.

That matches my experience.

I've written programs in Haskell, and it was very satisfying. But going back to the project after 6 months of work in other languages was very hard. I took some time to remember the concepts, the abstractions and what the cryptic operators meant in their contexts. I've kept away of Rust for this reason: maintenance would be hard if I only dabble episodicly in Rust.

On the other side, my own experience with Lua was not very nice. I contributed (and patched for my needs) Koreader, an ebook reader with 180k lines of Lua. The lack of explicit types and data structures was a strong impediment. And the language has subtle traps... Everything is a table, but not all tables are equals: some tables are sequences (indexed by 1..n) with special operators (like # whose result is undetermined for other tables (which hurts like the famous Undefined Behavior of C++). With Lua, simple questions like "Is this table empty?" or "What is the size of a table?" are too hard for beginners.

So, complex artefacts are hard to go back after a long break, but many toys break easily when you come back after a pause, having forgotten how fragile they were.

[nequo]

I find Rust much better on this front than Haskell. Haskell has a much stronger culture of using library-specific operators and abbreviations for function, variable, and type names, than Rust does. In Rust, you can’t even define a custom operator.

If you understand borrowing and some of the basic traits, you’re a long way there. There aren’t new DSLs to learn or relearn, and the documentation is good at closing any gaps that open up while you’re away from Rust.

[samatman]

> Everything is a table, but not all tables are equals: some tables are sequences (indexed by 1..n) with special operators (like # whose result is undetermined for other tables (which hurts like the famous Undefined Behavior of C++).

> #{}

0

[idoubtit]

IIRC, the right way to check if a table is empty is

    next(mytable) == nil

As the sibling comment points to, the documentation of the # operator is complex. It returns a border which is defined as:

    a border is any positive integer index present in the table
    that is followed by an absent index, plus two limit cases:
    zero, when index 1 is absent;
    and the maximum value for an integer, when that index is present.
    Note that keys that are not positive integers
    do not interfere with borders.

When the table has multiple borders, the behavior is undefined.

     lua         
    Lua 5.1.5  Copyright (C) 1994-2012 Lua.org, PUC-Rio
    > print(#{nil, 20})
    0
    > a = {10, nil}
    > print(#a)
    1
    > a[-1] = -10
    > print(#a)
    1
    > a[1] = nil
    > print(#a)
    0

[int_19h]

{} is explicitly defined as a sequence of length 0 by the language spec.

But for any table which has a nil in it between two non-nil values - i.e. non-sequences - there's basically no guarantees on which one of the several possible values # will return.

https://www.lua.org/manual/5.4/manual.html#3.4.7

[samatman]

Yes, that's true. What isn't true is that "some tables are sequences" which have "special operators" whose results are "undetermined for other tables".

A table has an array portion, it has contents or it doesn't, you can check this as I illustrated (I didn't intend it to check if the table is entirely empty, the sibling comment to yours shows how to do that). `#` works on any table.

It is in fact the case that if you start sticking `nil` into the contiguous array portion of the table, you'll have problems: `#` and `ipairs` won't work correctly. That's part of why `false` (and therefore `true`) were added to the language.

It's a quirk you have to know to use Lua effectively, that's all. In years of programming Lua, I've never had a bug which originated from adding `nil` within the array portion.

As the only composite data structure in the entire language, it's reasonable to expect people to learn how they work if they're using Lua. The one correct observation in the post I was replying is that there's no obvious or cheap way to find the number of entries in a table (other than the array portion). Luajit has `table.nkeys`, and that should have been imported into stock Lua.

There are a lot of anecdotes in this thread which amount to "my experience with Lua was as a means to an end: I was using it as a scripting language for something else, and it subverted my expectations in some way or another (mostly by not being Python)". Understandable in a way, but it should take half a day at most to read the entire manual and the online edition of Programming in Lua, and there's no sense in blaming the language because a user wanted to get something done and figured they would skip that part.

[int_19h]

The point is that # is basically unusable for non-sequence tables because there are no guarantees on which border it will return. But at the same time, when that happens, you do not get any clear error, either. That is the nasty part here, and it is exacerbated by the lack of any kind of static or even dynamic typing to distinguish sequences from non-sequences - e.g. Python is also a very dynamic language, and has a rich set of built-in data structures, but there's no point at which len() will silently do the wrong thing for any of them. Either a given collection type supports it, in which case you get a meaningful value, or it doesn't, in which case you get an error. In Lua, if you ever get an invalid table as input, you will silently get the wrong value which is nevertheless indexable, and so when you use it you get another wrong value etc, and eventually your computation just produces garbage output with no obvious clues as to where the error was introduced. That is a clear design defect in the language.

As far as personal experiences, I can't speak for OP, but I've learned Lua in early 00s, long before Python. As languages go, I don't think it's the worst dynamically typed language by far - it sure beats JavaScript, and Python could learn some things from it as well. But when it comes to long-term maintainability of large amounts of code, it is subpar.

[QuaternionsBhop]

I agree with this, but my point was that I cannot hide the details from myself, and will bring them up when they are relevant and confuse my poor friend just trying to learn Lua.

Definitely very little effort picking up my toy again after a 6 month break

[15155]

The zen comes from knowing when to carefully embed a Lua interpreter into your Rust program.

[interroboink]

I haven't used Rust, but lots of C++ — do you ever find the strongly-typed and compiler-driven approach constraining, compared to Lua?

Like, in C++ if I want to change the API for something, I need to update a few different places (header, implementation, maybe some downstream typedefs, etc.), maybe recompile a library or two, then re-run the application, whereas in a more loosly-typed and "interpreted" language like Lua, I can rely on duck typing and such, make my edits and save, and the code is immediately live.

The iteration cycle can be very short, if the system is built that way.

Anyway, maybe I just come from the opposite end of the spectrum, so Lua feels like a breath of fresh air sometimes vs. writing everything in a stricter language. My project is also very amenable to that, though.

[xedrac]

As a long time C++ developer with only a few years in Rust, C++ is downright painful in comparison. However, I still cannot iterate in Rust as quickly as I can in Lua, unless the project is large and complex, then I'd argue that I can work faster in Rust. Languages like Python, Lua, Lisp really struggle in large projects because it becomes way too easy to break things unknowingly.

[vindarel]

I question this belief for Lisp, because for instance SBCL says quite a lot of things at compile-time. See also the new Coalton (Haskell types), handy language features and the fast debug loop.

[xedrac]

That may be true. I was thinking more about elisp when I wrote this.

[QuaternionsBhop]

I know that I would have found strong types constraining when I first started learning Lua in 2009, but do you ever really need to change the type of a variable after you create it? I did a lot of hacks using ternary true-false-nil and drive-by appending random state to a table it doesn't belong in, to be recalled later in some other random place in the code. The lack of rules makes even following your own ideas of structure easy to cheat and subvert.

I think your comment about opposite end of the spectrum has merit, because I find the strict rules to be refreshingly binding to my coding ideals. Rust is ergonomic to think in, and I have even used it to prototype things before implementing them in Lua.

To me, Rust vs Lua is changing a struct and then simply following the chain of compiler errors instead of trying to remember every last place a mushy table gets manipulated.

[umvi]

Iteration cycle of strongly typed languages can be very short too, if you pick the right technologies. Rust (and c++), unfortunately, has pretty long compile times compared to, say, Go.

The problem with loosely typed languages is that you don't find out until runtime that you have a problem. And if the problem is inside an if statement that users only hit 1% of the time, you might not find it at all except in the form of users very occasionally complaining that it sometimes crashes unexpectedly.

[criddell]

IDEs are getting pretty good at refactoring these days. I do changes like that in Visual Studio and it has gotten remarkable good in the last few years.

[secondcoming]

There are techniques in C++ that can prevent this situation somewhat but it comes at the expense of indirection (see pimpl).

[wsc981]

> So far I have spent 6 months in Rust and my old tool looks like a toy. How did I ever live without iterators, algebraic data types, the safety of a strong type system, and especially separate types for arrays and hashmaps for god sakes?

I programmed in many languages with similar features (C#, Java, Swift, Objective-C) and programming in Lua is refreshing to me.

In daytime I can deal with doing C# at office, but at home, Lua is more fun to me. Great for hobby projects. Would probably love programming full-time with Lua as well (if I could make money with game dev).

[marcosdumay]

"Second System Effect from Within - A Documentary"