Local variables

Variables in Teal have types. So, when you declare a variable with the local keyword, you need to provide enough information so that the type can be determined. For this reason, it is not valid in Teal to declare a variable with no type at all like this:

local x -- Error! What is this?

There are two ways, however, to give a variable a type:

through declaration
through initialization

Declaration is done writing a colon and a type. When declaring multiple variables at once, each variable should have its own type:

local s: string
local r, g, b: number, number, number
local ok: boolean

You don't need to write the type if you are initializing the variable on creation:

local s = "hello"
local r, g, b = 0, 128, 128
local ok = true

If you initialize a variable with nil and don't give it any type, this doesn't give any useful information to work with (you don't want your variable to be always nil throughout the lifetime of your program, right?) so you will have to declare the type explicitly:

local n: number = nil

This is the same as omitting the = nil, like in plain Lua, but it gives the information the Teal program needs. Every type in Teal accepts nil as a valid value, even if, like in Lua, attempting to use it with some operations would cause a runtime error, so be aware!