Added November 2022 post

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Vyacheslav Egorov 2022-11-30 18:27:30 +02:00
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---
layout: single
title: "Luau Recap: November 2022"
---
While the team is busy to bring some bigger things in the future, we have made some small improvements this month.
[Cross-posted to the [Roblox Developer Forum](https://devforum.roblox.com/t/luau-recap-november-2022/).]
## Error messages
Error about function argument count mismatch no longer points at the last argument, but instead at the function in question.
So, instead of:
```lua
function myfunction(a: number, b:number) end
myfunction(123)
~~~
```
We now highlight this:
```lua
function myfunction(a: number, b:number) end
myfunction(123)
~~~~~~~~~~
```
Parsing now recovers with a more precise error message if you forget a comma in table constructor spanning multiple lines:
```lua
local t = {
a = 1
b = 2 -- Expected ',' after table constructor element
c = 3 -- Expected ',' after table constructor element
}
```
If you iterate over a table value that could also be '`nil`', you get a better explanation in the error message:
```lua
local function f(t: {number}?)
for i,v in t do -- Value of type {number}? could be nil
--...
end
end
```
Previously it was "`Cannot call non-function {number}?`" which was confusing.
And speaking of confusing, some of you might have seen an error like "`Type 'string' could not be converted into 'string'`".
This was caused by Luau having both a primitive type '`string`' and a table type coming from '`string`' library. Since the way you can get the type of the '`string`' library table is by using '`typeof(string)`', the updated error message will mirror that and report "`Type 'string' could not be converted into 'typeof(string)'`."
## Analysis improvements
For better inference, we updated definition of '`Enum.SomeEnumType:GetEnumItems()`' to return '`{Enum.SomeEnumType}`' instead of common '`{EnumItem}`' and the return type of '`next`' function now includes the possibility of key being '`nil`.'
If you use '`and`' operator on non-boolean values, '`boolean`' type will no longer be added by the type inference:
```lua
local function f1(a: number?)
-- 'x' is still a 'number?' and doesn't become 'boolean | number'
local x = a and 5
end
```