Lua will be 30 this year | Hacker News Reader

Lua will be 30 this year

lua.org

64 pointssquarefoot16 comments

Imagine the state of the world if Brendan Eich had known about Lua and spent those nine days integrating that into Netscape. I believe it had a compatible license, even back in 1995.

Then it would probably be frozen in time as Lua 1.0 without all of the breaking improvements that have happened since then

Lua is an embedded language and I think most users who want compatibility run or forked Lua 5.1, which is from 2006

It’s not clear to me that Lua in 1995 was better than JavaScript in 1995

Good answer. No coros, in particular.

https://news.ycombinator.com/item?id=1905155

Yeah imagine all the Lua transpiling we'd be doing.

Lua actually has a bunch of transpilers, like Moonscript.

Ah, Lua... That programming language that still invites you to implement a split function a zillion ways and get it wrong: http://lua-users.org/wiki/SplitJoin Found this out when I had to implement a snippet in nginx... Avoided at all costs since then.

Ah, lua-users.org... That wiki which pretty much looks like the comment section in the PHP manual but with a less chance to be correct for many reasons. And I'm not sure if there's other (preferably more trusted) source of snippets.

Back in time when I messed with Lua [1], I needed a version of `pairs` that returns keys in the sorted order. Lua-users has a page for that [2], so I looked it up, and found that it has a subtle but important enough bug---it relies on `__orderedIndex` stored in the original table, which never gets updated nor GCed. I'm sure many enough people had been and will be tripped up by this snippet.

[1] So much that I had written a type checker for Lua: https://github.com/devcat-studio/kailua/

[2] http://lua-users.org/wiki/SortedIteration

` t.__orderedIndex = nil` looks like it cleans up at the end of the iteration, am I missing something? Mutating a table while iterating over it is fairly hazardous anyway

Ah, yeah, the problem won't be visible with a normal loop. However if you break out of the loop without hitting the very last key, or remove a key during the iteration [1], or loop against the same table inside another loop, then the snippet will fail in unexpected ways.

The correct way to do this is as follows. First you collect all keys and sort them as usual, and then return an iterator function that contains those keys as an upvalue. Essentially you need to create a single-use `pairs` function that holds all necessary states.

[1] You can't insert a key during the iteration, but removing an existing key is guaranteed to work correctly, no matter if you've already past the deleted key or not: https://www.lua.org/manual/5.4/manual.html#pdf-next

Despite being linked on the website, no one should consider Lua Users wiki as any sort of canonical source of information. If you have questions use the mailing list, not that splitting a string is something that should require too much thinking, nor should we pretend there aren't a handful of mature utility libraries should you not be inclined to write a few lines of code yourself.

Lua is older than JavaScript and I want to believe, in an alternate universe, it supplanted it.

How did we manage to post that same observation almost simultaneously?

There's alot of similarities - weak dynamic typing, closures from day one, both came with mechanisms to do something like self-style prototype OO, only have a double for a numeric data type, both fairly small langs designed for "simple" scripting (though JS has grown).

great minds... :)

Scheme would have been a wonderful choice for browser scripting too. Alas.

And it will supplant javascript, as all the kids starting to code today use it (robblox and minecraft) (https://create.roblox.com/docs/tutorials/scripting/basic-scr... https://minecraftcomputercraft.fandom.com/wiki/Simple_Lua_(N...).

Then again its just syntax..

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