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.]
Analysis improvements
Indexing table intersections using x["prop"] syntax has been fixed and no longer reports a false positive error:
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:
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 toT | TorT?which could’ve generated confusing errors - Return type of
os.dateis now inferred asDateTypeResultwhen 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.sortwas improved further. It now guarantees N*log(N) time complexity in the worst case - Performance of
table.concatwas improved by ~5-7% - Performance of
math.noisewas 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:
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: