Why result of [[1]] is equal to '1' in Lua language?

Question

[[1]]

WithLua 5.4.3, On expression [[1]], And result is '1',type is string. I can not understand, and not find any useful info on Lua document.

Answer 1

https://www.lua.org/manual/5.4/manual.html#3.1

It's introduced in section 3.1.

Literal strings can also be defined using a long format enclosed by long brackets. We define an opening long bracket of level n as an opening square bracket followed by n equal signs followed by another opening square bracket. So, an opening long bracket of level 0 is written as [[, an opening long bracket of level 1 is written as [=[, and so on.

The long format is usually used to write multiline literal strings and multiline comments.

print([===[
"Hello
world!"]===])

--[=[
"Hello
world!"
]=]