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LuaJIT 3.0 proposed syntax extensions(github.com)
60 points by phreddypharkus 2 hours ago | 31 comments
Heliodex an hour ago | parent | next [-]

A comment <https://github.com/LuaJIT/LuaJIT/issues/1475#issuecomment-47...> has already been made on the issue regarding the ternary operator, recommending `if x then y else z` over `x ? y : z`. This is exactly how it's done with if-then-else expressions in Luau <https://luau.org/syntax/#if-then-else-expressions>, another language compatible with Lua, and makes it a ton easier to nest (especially with elseif) and I believe still easier to read than `y if x else z`.

mjcohen 32 minutes ago | parent [-]

The ternary operator is easy to nest if you put each clause on a separate line. Then it looks just like nested if-then-else.

edoceo a minute ago | parent [-]

I love the ternary operator as much as anyone. But dang if it doesn't get hard to read when there is are a few, nested even.

Does that operator compile to faster assembly that if I make the same logic with verbose `if` logic? Is that a language specific outcome?

3eb7988a1663 an hour ago | parent | prev | next [-]

Never will I understand ternary operators. As soon as you introduce it, some chuckle heads want to use them everywhere. Worse if the syntax allows nested ternarys. I guess it keeps the language open for code golfing, but it otherwise seems like redundant syntax that at best saves a few characters.

201984 an hour ago | parent | next [-]

Lua basically already has ternary operators anyway since "and" and "or" short circuit. I also don't see the need of adding additional syntax for it.

  local x = condition ? value_a : value b
  local x = condition and value_a or value_b
matheusmoreira an hour ago | parent [-]

> The classic Lua idiom a and b or c has a pitfall when b is nil or false: then c is returned, even when a is truthy.

> E.g. true and false or 42 returns 42, whereas true ? false : 42 returns the (expected) false.

demilicious an hour ago | parent | prev | next [-]

That’s why “if” should just be an expression

matheusmoreira an hour ago | parent [-]

This is the best answer in my opinion. Ternary is just sugar for an expressive if. LuaJIT seems to be focusing on adding new syntax though, maintainer might not be amenable to updating existing semantics.

hiccuphippo an hour ago | parent | prev | next [-]

I find it most useful in languages that have non-mutable variables and you want to avoid a mutable variable or an extra function when the value comes from a simple condition.

Gualdrapo an hour ago | parent | prev [-]

I guess for the JS case it makes sense to be able to shave a few characters for file shrinking purposes, but generally I'm more biased to code clarity and "self-explainability"

ricardobeat an hour ago | parent | prev | next [-]

I see JavaScript.

Some of these really look like QoL improvements. I'm not convinced ternary statements are an ergonomic improvement in particular. The examples given don't make a compelling case, 'visually tidy' is not the same as readable.

nine_k 40 minutes ago | parent [-]

Worse, I see C (as in ! or &&), and Perl (as in manifestly more than one way to do it).

There are real improvements though, such as ?. and ??= that help with default-nullable everything.

Ternary is very useful, but it I'd rather see it implemented idiomatically:

  pos += (if forward then +1 else -1)
Structural pattern-matching could be fantastic, but no syntax is suggested.
pansa2 an hour ago | parent | prev | next [-]

So is LuaJIT resuming active development after a decade or so of only maintenance? Great!

A lot of these changes make sense (although some of them are a bit too TIMTOWTDI for my taste) - but perhaps LuaJIT 3 would benefit from a change of name as well? Certainly with all these changes, it would be more like a separate language than merely a JIT-compiled version of Lua.

201984 an hour ago | parent [-]

>TIMTOWTDI

What on earth is this supposed to mean?

Twirrim an hour ago | parent | next [-]

There Is More Than One Way To Do It.

That takes me back a bit. It's a perl-ism. I used to think it was a great design feature but I've come to strongly prefer "There should be one way to do it, and it should be obvious"

201984 an hour ago | parent [-]

Interesting, thank you.

matheusmoreira an hour ago | parent | prev [-]

There is more than one way to do it.

JSR_FDED 10 minutes ago | parent | prev | next [-]

What’s the Lua/LuaJIT story these days for bundling up all the scripts of an application into a single file? Is there a way to do the super convenient go-like thing?

matheusmoreira an hour ago | parent | prev | next [-]

Looks like LuaJIT is really going to fork away from Lua this time. After these changes, it won't be a compatible Lua 5.1 implementation anymore, it will be a new language.

So shouldn't it have a new name?

sourcegrift 11 minutes ago | parent | next [-]

Are there any rough estimates on popularity of lua implementations? At this point it feels lua means luajit

latenightcoding 7 minutes ago | parent [-]

not even close, because there are a lot of places where you can't run LuaJIT

a_t48 38 minutes ago | parent | prev [-]

It could be opt in.

bawolff an hour ago | parent | prev | next [-]

+= and ..= are things i find i'm constantly missing in lua.

Personally im a fan of introducing ternaranary operator in lua. Everyone uses `x and y or z` as a ternanary which i find way more confusing than ?:

larrry 44 minutes ago | parent | prev | next [-]

I would love to see all of these come to LuaJIT (and love2d to support the new version too). It’s nice that Lua is simple, the syntax changes should hopefully make Lua code even simpler to read too

Rohansi 36 minutes ago | parent [-]

> It’s nice that Lua is simple, the syntax changes should hopefully make Lua code even simpler to read too

But which Lua?

Lua as implemented by LuaJIT is a fork of the language at this point. It's not fully compatible with PUC Lua (the reference implementation) and LuaJIT does not support features from the latest Lua version.

JSR_FDED 14 minutes ago | parent | prev | next [-]

Cool to see this - ergonomic syntax will make it easier to recommend Lua. Hope the PUC team aligns with this.

Also, I love this kind of pragmatism:

> Exponentiation assignment a ^= b has been deliberately omitted to avoid a predictable pitfall: this is how xor assignment is written in most other computer languages. Also, a syntax for exponentiation assignment is rarely asked for.

A ‘defer’ for closing files or deleting temp files at the end of a script will make life more enjoyable.

le-mark an hour ago | parent | prev | next [-]

I’m confused I thought Mike Pall left luajit and Laurence Tratt took over as maintainer?

kibwen 14 minutes ago | parent | prev | next [-]

Please don't, inscrutable bitwise operators are an accident of the past even in systems languages, let alone in a scripting language. I'm not against infix operators for bitwise operations, just please spell them out with keywords rather than giving them sigils.

Likewise, going from `and` and `or` to `&&` and `||` would be a dispiriting regression. This is something that Zig got right.

JSR_FDED 8 minutes ago | parent [-]

The btiwise operators library doesn’t go away

sourcegrift 16 minutes ago | parent | prev | next [-]

What are some pragmatic embedded scripting languages of choice these days if one has to consider:

1) Ease of learning, ideally minimal deviant behaviour (eg i consider lua tables to be a new concept in itself)

2) Reasonably fast. Not as much as lua jit but even half would be good enough

3) Mature

4) Has Rust bindings

linzhangrun an hour ago | parent | prev [-]

I thought luajit had completely stopped feature updates