luau/docs/_posts/2023-07-28-luau-recap-july-2023.md
2023-07-31 13:02:24 -07:00

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---
layout: single
title: "Luau Recap: July 2023"
---
Our team is still spending a lot of time working on upcoming replacement for our type inference engine as well as working on native code generation to improve runtime performance.
However, we also worked on unrelated improvements during this time that are summarized here.
[Cross-posted to the [Roblox Developer Forum](https://devforum.roblox.com/t/luau-recap-july-2023/).]
## Analysis improvements
Indexing table intersections using `x["prop"]` syntax has been fixed and no longer reports a false positive error:
```lua
type T = { foo: string } & { bar: number }
local x: T = { foo = "1", bar = 2 }
local y = x["bar"] -- This is no longer an error
```
Generic `T...` type is now convertible to `...any` variadic parameter.
This solves issues people had with variadic functions and variadic argument:
```lua
local function foo(...: any)
print(...)
end
local function bar<T...>(...: T...)
foo(...) -- This is no longer an error
end
```
We have also improved our general typechecking performance by ~17% and by additional ~30% in modules with complex types.
Other fixes include:
* Fixed issue with type `T?` not being convertible to `T | T` or `T?` which could've generated confusing errors
* Return type of `os.date` is now inferred as `DateTypeResult` when argument is "*t" or "!*t"
## Runtime improvements
Out-of-memory exception handling has been improved.
`xpcall` handlers will now actually be called with a "not enough memory" string and whatever string/object they return will be correctly propagated.
Other runtime improvements we've made:
* Performance of `table.sort` was improved further. It now guarantees N*log(N) time complexity in the worst case
* Performance of `table.concat` was improved by ~5-7%
* Performance of `math.noise` was improved by ~30%
* Inlining of functions is now possible even when they used to compute their own arguments
* Improved logic for determining whether inlining a function or unrolling a loop is profitable
## Autocomplete improvements
An issue with exported types not being suggested is now fixed.
## Debugger improvements
We have fixed the search for the closest executable breakpoint line.
Previously, breakpoints might have been skipped in `else` blocks at the end of a function.
This simplified example shows the issue:
```lua
local function foo(isIt)
if isIt then
print("yes")
else
-- When 'true' block exits the function, breakpoint couldn't be placed here
print("no")
end
end
```
## Thanks
A very special thanks to all of our open source contributors:
* [Petri Häkkinen](https://github.com/petrihakkinen)
* [JohnnyMorganz](https://github.com/JohnnyMorganz)
* [Gael](https://github.com/TheGreatSageEqualToHeaven)
* [Jan](https://github.com/Jan200101)
* [Alex Orlenko](https://github.com/khvzak)
* [mundusnine](https://github.com/mundusnine)
* [Ben Mactavsin](https://github.com/BenMactavsin)
* [RadiatedExodus](https://github.com/RealEthanPlayzDev)
* [Lodinu Kalugalage](https://github.com/imlodinu)
* [MagelessMayhem](https://github.com/MagelessMayhem)
* [Someon1e](https://github.com/Someon1e)