Round Parenthesis

(Round) Parenthesis () have two purposes in Lua:

• Grouping operations: (1 + 2) * 4 is 3 * 4 rather than 1 + 8.
• Calling functions: In print( 5 ), a name followed by ( indicates that you call (use) that name as a function. They are read like of. For example, math.sqrt( 5 ) is "the square root of 5".

Square Brackets

Square brackets/braces [] are used in a way similar to () when calling -- they are used to index. They answer what is at a location.

list[1] is the thing at position 1 in list.

map[blah] is the thing at the key with the value blah inside map, map["prop"] gets the property called prop in map.

Curly Braces

Curly braces {} are used to define tables -- tables have two main forms -- dictionaries (also called maps or hashmaps) and lists (also called arrays).

The things inside of a table are separated by commas , or semicolons ; (these are equivalent). Usually , is used. Note that you are allowed to have a "trailing" comma or semicolon. This is ungrammatical in English but can be desirable for programming (especially with version control)

Entries in a table have three forms:

List values are simply the bare value: list = {1, 2, 3}.

Named properties can be written with a property=value format:

Bob = {
    name = "Bob",
    occupation = "Programmer",
    age = 20,
}

Properties at others keys can be used using [] to indicate where they are in the form [key] = value:

Bob = {
    ["name"] = "Bob",
    ["favorite-color"] = "blue",
    [1995] = "birth",
    [math] = "favorite library",
}

Square brackets are for Arrays and Tables. For example, in this table:

local Table = {"First", "Second", "Third"}

To access "Second" you would say:

Table[2]