Lua by Example: Functions

Functions are central in Lua. We’ll learn about functions with a few different examples.
Here’s a local function that takes two `number`s and returns their sum. Note: functions are global by default.	local function plus (a, b)
lua requires explicit returns, i.e. it won’t automatically return the value of the last expression.	return a + b end
Call a function just as you’d expect, with `name(args)`.	print("1+2 =" .. plus(1,2))
Because functions are first-class values in Lua, we can store them not only in global variables, but also in local variables and in table fields. As we will see later, the use of functions in table fields is a key ingredient for some advanced uses of Lua, such as packages and object-oriented programming.	local subtract = function (a, b) return a - b end
And can be called the same way	print("2-1 =" .. subtract(2,1))
Functions without the `local` keyword become available in the global namespace. This distinction becomes important in larger Lua programs where where lua files are required by other lua files.

	$ lua functions.lua 1+2 =3 2-1 =1
There are several other features to lua functions. One is multiple return values, which we’ll look at next.