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Lua, finished

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liquidex 2024-03-08 23:41:39 +01:00
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commit 7b15444198
3 changed files with 144 additions and 11 deletions
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2
content/programming.tree
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@ -15,6 +15,7 @@
id = "01HPD4XQQ5WM0APCAX014HM43V"
+ tairu - an interactive exploration of 2D autotiling techniques
% id = "01HRG2RJCNKT9JJJVQ8WVRC9CA"
- ### languages
% content.link = "programming/languages/cxx"
@ -25,6 +26,7 @@
id = "programming/languages/lua"
+ ### Lua
% id = "01HRG2RJCN8J42NK0KWD3SBSJA"
- ### technologies
% content.link = "programming/technologies/unreal-engine"

152
content/programming/languages/lua.tree
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@ -1,33 +1,54 @@
% id = "01HRG2RJC1BATZJSGSSSF1XNFZ"
- TODO: this page could really use an interactive Lua interpreter. can we have that?
% id = "01HRG2RJC1J57MFVA0QFXP8WWW"
- Lua is a really cool language! did you know that?
+ lots of people complain about it being really weird for various reasons, but these are generally superficial
% id = "01HRG2RJC1N1J4FTZ4M4MW72VZ"
- lots of people complain about it being really weird for various reasons, but these are generally superficial
- usually it's cosmetic stuff, so these aren't any arguments of technical merit, but...
% id = "01HRG2RJC1637T8NPCWH90E5W0"
- usually it's cosmetic stuff, so these aren't any arguments of technical merit, but…
% id = "01HRG2RJC10G9GEGM5JCX32FE4"
- stuff like indexing from 1 instead of 0, which is _just a design choice_ and does not impact your programming that much
% id = "01HRG2RJC1MTW370DDEXQ0AN72"
- in fact, one could argue that regular programmers are weird for counting from zero :thinking:
% id = "01HRG2RJC1DH3WE4VGQCMEDN15"
- the biggest impact this has is on rendering code, where you have to subtract 1 to position things relative to the origin - which is at `(0, 0)` (or `(0, 0, 0)` in 3D.)
% id = "01HRG2RJC1VJ5FDDM8X9ECB3HR"
- or using `~=` instead of `!=`, which is _just a syntax choice_, and you only have to get used to it once
% id = "01HRG2RJC160QD16204NDAYTSW"
- or using `do`..`end` style blocks instead of `{`..`}`, which again is _just a syntax choice_ and does not impact programming that much
% id = "01HRG2RJC1D377M98MDT9BX8EQ"
- it's a tad bit more line noise, but not that terrible. I [did design a language using `do`..`end` blocks][def:mica/repo] and it really doesn't look that bad
% id = "01HRG3MJ0KRVRWEMRKX8TQFZAK"
- TODO: this section could use some links to actual complaints or statistics or something. anecdotal evidence is not evidence.
% id = "01HRG2RJC1RTAJJ1MX2JZAMBW8"
- but I think Lua is a pretty damn genius programming language.
% id = "01HRG2RJC11KMM8AVCSSQ96H26"
- the use of tables as The One Data Structure for Literally Everything strikes me as a 200 IQ choice I could never come up with myself
% id = "01HRG2RJC1SJSFQSR1X3TT638F"
- partly because it's so fucking bold I can literally not imagine myself designing a language with a strong distinction between hash tables and arrays, and even tuples and records!
but the authors of had the restraint to just have One. and that One is **tables.**
but the designers of Lua had the restraint to just have One.
% id = "01HRG2RJC13YK030EPGMKM9H8H"
- tables are extremely powerful in what they can do, because they're more than just a way of structuring data - they also allow for interfacing with the language *syntax* through operator overloading
% id = "01HRG2RJC1PDZFB2WBW7D827KF"
+ in fact object oriented programming in Lua is typically done by overloading the `[]` indexing operator.
- the way it works is that `a.b` is just syntax sugar for `a["b"]`, which means you overload `[]` to _fall back to another table_ - and that way you can achieve [prototype-based inheritance](https://en.wikipedia.org/wiki/Prototype-based_programming)!
% id = "01HRG2RJC1HK3SG51X6DJFCD0B"
- the way it works is that [`a.b` is just syntax sugar for `a["b"]`][branch:01HRG2RJC2PA5KE0DH0RRFGW9E], which means you overload `[]` to _fall back to another table_ - and that way you can achieve [prototype-based inheritance](https://en.wikipedia.org/wiki/Prototype-based_programming)!
```lua
local fallback = { b = 2 }
@ -39,25 +60,133 @@
assert(base.b == 2)
```
- TODO: even more on restraint (standard library)
% id = "01HRG2RJC23XH1053A69MQJD4N"
- I'll be honest that I don't like the standard library of Lua from a usability standpoint, but maybe it *doesn't need to be bigger*.
it's similar to the principles of [Go](https://go.dev/), where the language encourages using dumb constructs rather than super clever code with lots of abstraction.
- TODO: restrained sugar: function calls `require "abc"`, `do_stuff { with_a_table = 1 }`
% id = "01HRG2RJC2P3832KTQMANBHGE6"
- though unlike Go, Lua has the goal of being *small* because it needs to be *embeddable*, especially given it's used in very constrained environments in the real world. (microcontrollers!)
% id = "01HRG2RJC2S3V38FM6DB0481WK"
- therefore there are technical, not just ideological reasons to keep the library small.
% id = "01HRG2RJC2KPZXH90Z6B92ZNB6"
- and I really like that from an embedder's standpoint, it's possible to completely disable certain standard library modules for sandboxing!
% id = "01HRG2RJC2W4MK96FMWRTS8QCJ"
- Lua also knows *very* well how much syntax sugar to have to make writing code pleasant, but not to overdose it so much as to give you instant diabetes.
% id = "01HRG2RJC28DT0TZT47WPABD65"
+ as an example, there's function call syntax: you can pass it a string or table *literal*, which is just enough to enable some really nice DSLs without making the grammar too complex.
% id = "01HRG2RJC2CVKS9CFVQ9HJSBH4"
- once upon a time I dreamed up a DSL for building GUIs using this sugar.
```lua
render {
width = 800, height = 600,
title = "Hello, world!",
vertical_box {
header1 "Hello, world!",
header2 "This is an example GUI.",
}
}
```
% id = "01HRG2RJC2T7BF6XS3T7Q8AXW2"
- ***JUST LOOK AT HOW CLEAN IT IS!*** with no need to [invent magic syntax](https://www.typescriptlang.org/docs/handbook/jsx.html) or anything!
% id = "01HRG2RJC2D69JYCWQXSF2FQNY"
- the only missing thing then would be list comprehensions to be able to transform data into GUI elements, but even that can be ironed over using function literals:
```lua
render {
width = 800, height = 600,
title = "Hello, world!",
vertical_box {
header1 "Hello, world!",
paragraph "This is an example GUI. Here's a horizontal list of numbers:",
horizontal_box {
function (t)
for i = 1, 10 do
t[i] = paragraph(tostring(i))
end
end,
}
}
}
```
interpret this code however you want, but *damn* it looks clean. again with no magic syntax!
% id = "01HRG2RJC2PA5KE0DH0RRFGW9E"
- there is also the incredibly useful sugar for indexing tables by string literals: instead of `table["x"]` you can write down `table.x`
% id = "01HRG2RJC2WDXCPW12JDD4749R"
+ and there is also the incredibly useful method call sugar `table:func()`, which gets transformed to `table.func(table)`;
and function definitions like `function table:func() end` are sugar for `function table.func(self) end`. ain't that neat and simple, yet super useful?
% id = "01HRG2RJC23955SMQXHWEA202J"
- if you don't get the usefulness: this is needed because object oriented methods in Lua are implemented using regular functions; there is no magic `this` or `self` parameter.
the parameter is explicit, there is just sugar for passing it into functions and declaring functions with it.
% id = "01HRG2RJC2FF05JWQ6KHS4Y5WF"
- I really wish Lua had at least *a* form of static typing though, since knowing about errors you make early is _really_ helpful during development.
- it regularly happened to me that a type error I made only occured at *some point* later during runtime; and then you have to track down a reproduction case and make a fix at the source. not fun.
% id = "01HRG2RJC2JP3HRTVMAQ22HDVE"
+ it regularly happened to me that a type error I made only occured at *some point* later during runtime; and then you have to track down a reproduction case and make a fix at the source. not fun.
% id = "01HRG3MJ0KGZ8T4KHMV6KZXDK4"
- there's also the ugly case I had with a division by zero in the last rewrite of [Planet Overgamma][def:planet_overgamma/repo], which caused a NaN to propagate through physics and into rendering, causing a crash.
% id = "01HRG3MJ0KKMR7MDXST9PCYF6Q"
- this is precisely where [my hate for NaN propagation][branch:01HPEMVAH9JZWYPVN53GVFQNQY] was born.
% id = "01HRG2RJC224TNYEWGRBCTJA0S"
- there's [Teal](https://github.com/teal-language/tl) but last time I checked it didn't have support for inheritance, which is heavily used by [LÖVE](https://love2d.org/), which is my go-to Lua graphics framework.
% id = "01HRG2RJC2JS0JXFM23SWHKTFN"
- you can also compile [TypeScript to Lua](https://typescripttolua.github.io/), which is insanely silly, but has the advantage of using a language that's more familiar to a very wide group of people.
I wouldn't use it though because TypeScript and Lua are very different languages, and I'm afraid certain transforms would be unobvious - which would make interfacing with existing Lua code harder.
I think I prefer the bolt-a-type-system-onto-Lua approach of Teal in that regard.
% id = "01HRG2RJC29C751N6A90G8RENK"
- and it's really a bummer that Lua is not that strict!
% id = "01HRG2RJC2EGS11ERP93BY5BVK"
- global variables by default are a pretty bad design choice in my opinion. having any form of uncontrolled globals hurts local reasoning and makes it harder to tell whatever your code is going to do.
- but fortunately it is possible to freeze your global variables by setting a metatable on `_G`, which is a table that represents the global scope.
% id = "01HRG2RJC2VMCBATX88ZE7SYA0"
- but fortunately it is possible to freeze your global variables by overloading the indexing operators of `_G` - the table that represents the global scope.
- TODO: example
```lua
setmetatable(_G, {
__index = function (t, k)
-- Only tell the programmer about undeclared variables. We still want access to
-- builtins like `require`.
if t[k] == nil then
-- The error message is purposefully generic because this will probably happen
-- the most when misspelling variables.
error("variable '"..k.."' was not declared in this scope")
end
return rawget(t, k)
end
__newindex = function (t, k, v)
-- Assigning to global variables usually happens due to typos with local variables,
-- so again - the error message is intentionally generic.
error("variable '"..k.."' was not declared in this scope")
end
})
```
- there are also some bits of syntax that haven't aged very well.
% id = "01HRG2RJC229JBT8YQFE3P1V8C"
- there are also some bits of syntax that arguably haven't aged very well.
- as much as people complain about cosmetics [TODO: link], I think there's a particular design choice that has aged very poorly in the face of modern, functional programming - function literals.
% id = "01HRG2RJC2N52T5X32YKPWP317"
- as much as people [complain about cosmetics][branch:01HRG2RJC1VJ5FDDM8X9ECB3HR], I think there's a particular design choice that has aged very poorly in the face of modern, functional programming - function literals.
these tend to be quite verbose in Lua which hurts readability in functional code:
@ -71,4 +200,5 @@
let u = t.map(v => v + 2)
```
% id = "01HRG2RJC2CS2MA98TTHK7MBQ9"
- the lack of a pipelining operator `|>` is also an annoyance, albeit most modern imperative languages don't have it either.

1
treehouse.toml
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@ -24,6 +24,7 @@ description = "a place on the Internet I like to call home"
"abit/repo" = "https://github.com/abyteintime/abit"
"rokugo/repo" = "https://github.com/rokugo-lang/rokugo"
"mica/repo" = "https://github.com/mica-lang/mica"
"planet_overgamma/repo" = "https://github.com/liquidev/planet-overgamma"
# Blog posts I like to reference
"article/function_coloring" = "https://journal.stuffwithstuff.com/2015/02/01/what-color-is-your-function/"