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Comment by Sebb767 | Hacker News Reader

> Lua is the only language I can truly say I love

Why? I've worked with Lua before and to me it's not a bad language, but nothing special either. I'm honestly wondering.

One aspect of Lua that stands out to me is how every feature is carefully designed both in isolation and in composition with the others. The language has relatively few features, but none of them are hanging off the side, the all lean on each other to make a cohesive whole.

I think Lua is a bit unique in this for two reasons. First, they have in intentional open-source but not open development model. Second, because of the way that Lua is embedded inside other projects, there is more willingness to implement backwards-incompatable changes. I'm sure this is a negative for some who want to build a larger, less fractured community, but it has advantages for language cohesiveness.

It has all the power of something like Python, but is much faster and with far less cruft and basically no confusing elements.

You’re given a small set of tools and it’s incredibly easy to build off them.

> basically no confusing elements.

the one confusing element - one-based indexing of arrays! that is something i found hard to adjust, as it makes off-by-one errors more prominent...

but otherwise it's a nice language.

That's not really confusing though, just takes a bit of unlearning the muscle memory of 0-based indexing.

I certainly prefer 0-indexed these days, but starting on 1-indexed languages (A variety of BASIC’s) I found 0-indexing just as weird.

I agree, that's the one unfortunate flaw of Lua I'd go back in time and change if I were Hitler With a Time Machine, but I've used Lua and other 1-based languages like ScriptX, and you totally get used to it, and finally realize that 0-based languages have their own confusing quirks and inconveniences that you got used to when you learned them, and you just don't think about them any more once you've internalized them, just like 1-based languages. It's just a matter of moving the confusing quirks and complexity around, not that 0-based languages are less confusing, complex, or quirky than 1-based languages, or the other way around.

But that said, I'd prefer that Lua had 0-based indexes, simply because that's what most other languages have, not because it's superior.

> It's just a matter of moving the confusing quirks and complexity around

unless you can exclusively program in 1 language only, these confusions would be the cause of various bugs, or at least, increase the cognitive load. Programming is already hard enough, without artificially increasing the cognitive load!

Same here. It's not a big deal once you get used to it but after years of always having indexes start at 0 it just seems... off.

If you learned arrays in C where indexing is the same as pointer arithemetic then zero-based arrays seem natural. If you are coming from the real-world concept of "a list of things" then the "zero-th item" in the list seems odd; one-based indexing feels natural.

iirc, one other confusing element is that tables (hash tables? I don't remember what they're called) return null when a lookup is done for a nonexistent key.

This is not necessarily a bad choice. Exceptions and such can be a real pain. However, accidentally getting a null value because you didn't check and then have it propagate much further in your program is extremely difficult to debug. Instead of blowing up at the site of the bad lookup, you only see the distant effects of it (e.g. put the null value into another table, which gets put in another table, and then is attempted to be called as a function, etc).

It even does this for globals (which are just another table), so there’s never an “undefined variable” error (even though there really is).

It’s pretty unfortunate. You can mitigate it using meta tables though.

Storing a null value is a legitimate operation. How do you distinguish "never stored a value under key K", and "stored null under key K"?

I'm pretty sure you're agreeing with them. Current Lua does this, which is wonky:

    > t = {}
    > t['a'] = nil
    > t['a']
    nil
    > t['b']
    nil

Give Teal [1] a look. It’s basically typescript for Lua

https://github.com/teal-language/tl

If you work with pure Lua that’s a non issue. The ipairs function abstracts that away, and for numerical loops are written different than in C, with a start value (included), an end value (included) and a step (optional), and no exit condition. You can’t put i<len there as a result like you would do in C.

Agreed that interaction with C or other 0-based languages or systems (eg screen coords) makes things more difficult.

Why would Lua be significantly faster than Python? Isn't it an interpreted language too?

The JIT version of LUA, according to some benchmarks I just saw, is similar to C in performance.

The Lua interpreter is really lightweight, and for decades has been the go to choice for when you need dynamic code and speed (for example, it's been popular in the games industry for this reason).

Probably someone else can shed light on exact numbers, but Lua is faster than Python.

It's also very small. We used it extensively on embedded Linux devices in the 2000s for these reasons as well as easy interop with C/C++.

I'm still using Lua on embedded Linux devices, and in fact completed a project last year that was deemed impossible by the Java devs, but easily within our memory/time budget as a Lua group. The success of that embedded Lua project converted a large number of Java diehards into Lua accolytes...

Folks who sniff at putting a scripted/interpreted language into an embedded environment really need to think twice with Lua. It is fast, tight and highly performant - and if you bundle it along with LuaJIT and Turbo.lua, it'll give you the best of all worlds - aynsc i/o, coroutines, very, very fast performance and a great execution environment upon which to build truly useful apps.

Isn't it LuaJIT that's really fast? Last I remember reading about it, there was some version fragmentation going on with Lua advancing and LuaJIT stuck on an older version? (That was a long time ago, and I don't know what been happening since.)

Yes, Lua’s now on version 5.4 and LuaJIT is stuck half-way between 5.1 and 5.2.

And LuaJIT has historically been extremely fast (initially much faster than JavaScript's early JITs) because it didn't have nearly as many optimizer-busting design flaws to work around as JavaScript JITs did, because Lua's language design is so much simpler and cleaner than JavaScript's, which wasn't originally designed to be compiled (cough cough "with" cough "this"). But because JavaScript was the "Chosen Language", a whole lot of effort has been put into developing JITs that worked around JavaScript's flaws over the decades since. But all that effort could have been put to much better uses if it didn't have all those flaws in the first place.

Lua definitely does not have the power of something like Python.

That's usually what people like about Lua: it's barebone, yet high level and clean.

If one likes Python, then the chance of liking Lua are low.

E.G:

Both python and lua can open something (a file, a socket, a transaction...) in one line.

But only Python has the `with` construct that means it's easy to guaranty you close it in case of an error.

Lua is then easier to learn: one less concept to master. But the high level tool of Python, that you had to learn, make your life easier.

They have very different trade off.

> If one likes Python, then the chance of liking Lua are low.

I don't know. I quite like both as well. The design ethos feels similar although Python has certainly added more features over the years.

"with" existed in python 2. In python 2.6 in fact, like comprehension lists, decorators, generators, descriptor protocol, exotic slicing assignation, advanced nested unpacking, infinite parameters...

Python was always chock-full of advanced features, people just usually don't notice because they get productive in 3 days with the basic features and don't need to go further. It's has the quality of a very smooth learning curve, but a very long one if you care.

"with" and "defer" (Go) are nice but not crucial to me.

My point exactly.

Lua 5.4 has to-be-closed variables that are similar in functions to with blocks in python.

Unkike the __gc hook which provides no guarantee as to when it will be called, if ever, the __close hook is called when a value goes out of scope.

http://www.lua.org/manual/5.4/manual.html#3.3.8

Not OP, but for me, I love Lua because it’s both easy-to-use and simple. Python is the former and Go is the latter, but I don’t know any other mainstream language that’s both.

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