How to define a tuple?

[danielo515]

Hello.
I want to define a type which is a list with a fixed length and fixed types on each index.
I tried several iterations, none of them work as I want. What is the best way?
This is what I tried

---@alias string_tuple [string, string]
---@alias string_tuple { _0: string, _1: string  }
---@alias string_tuple { 0: string, 1: string  }

[haolian9]

As a beginner of lua, I once wanted to use tuples too, but I gave up at last, hehe.
And from what i found on the internet, there is no big performance benefit on preferring tuples over dicts, so i turned the need of tuples into namedtuples (python term), ---@alias string_tuple {x: string, y: string}, the downside is I can not use unpack on it.

[danielo515]

Thanks for sharing your experience. Indeed named tuples is a viable alternative, but it is not as simple as just 0 and 1, but I think it's ok

[sewbacca]

I'm guessing there might be a performance benefit to using tables as arrays instead of maps, since they are also stored as an array in memory, though it depends on the use case and would require profiling to find out if there are any actual benefits.

[sewbacca]

Integer keys have to be indexed with [] like in ordinary Lua.

[haolian9]

wow, you are right!

my previous reply was based on this broken annotation ---@alias bar {1: number, 2: number}.
now I see, local bar = {1 = 1, 2 = 2} is not a valid syntax in lua.

[C3pa]

You can follow on more-or-less related issue here: #1081