Types & Values

LuaLuaA lightweight, embeddable scripting language used as the primary scripting language in FiveM server development. is dynamically typed. Every value carries its own type. There are eight basic types:

Type	Description
nil	Absence of a useful value
boolean	true or false
number	Integer (64-bit) or float (double)
string	Immutable byte sequence, 8-bit clean
function	First-class callable (LuaLuaA lightweight, embeddable scripting language used as the primary scripting language in FiveM server development. or C)
userdata	Opaque C data allocated by LuaLuaA lightweight, embeddable scripting language used as the primary scripting language in FiveM server development.
thread	Coroutine (independent execution thread)
table	Associative array — the only data structure

[!important] Truthiness Only nil and false are falsy. Everything else — including 0 and "" — is truthy.

---

nil

Represents "no value". Unset table fields return nil. Global variables default to nil.

print(x)       -- nil (x not defined)
local t = {}
print(t[1])    -- nil (key not present)

---

boolean

Two literal values: true and false.

if not false then print("ok") end  -- ok

---

number

Two subtypes, automatically coerced:

Subtype	Default	Size
integer	64-bit signed	-2^63 to 2^63 - 1
float	double-precision	IEEE 754

Integer literals

3       345     0xff     0xBEBADA
0xAA    -127    0x10     0xdeadBEEF

Float literals

3.0     3.1416     314.16e-2     0x1.fp10
0.3     .3         1.2e-20       0x0.1p-1

Coercion rules

• Arithmetic on two integers → integer
• Arithmetic with at least one float → float
• math.type(x) returns "integer" or "float"

print(1 + 2)          -- 3 (integer)
print(1 + 2.0)        -- 3.0 (float)
print(math.type(3))   -- integer
print(math.type(3.0)) -- float

[!warning] Integer overflow Integer arithmetic wraps around on overflow (two's complement).

---

string

Immutable sequences of bytes. Encoding-agnostic (works with UTF-8 but doesn't enforce it).

Literal forms

-- Single or double quotes
'hello'
"hello"

-- Escape sequences
'alo\n123"'          -- newline, escaped quote
'\97lo\10\04923"'    -- decimal byte codes

-- Long strings (brackets, ignore leading newline)
[[multi
line
string]]

-- Nested brackets (any level of = signs)
[==[can contain ]] inside]==]

String operations

#s              -- length (bytes)
s1 .. s2        -- concatenation (creates new string)
string.byte(s)  -- byte values
string.char(97) -- "a"
tostring(x)     -- convert to string
tonumber("42")  -- convert to number

[!tip] Strings are interned Equal strings share the same memory. Comparing by content is O(1).

---

function

First-class values. Can be stored in variables, passed as arguments, returned from functions.

local f = function(x) return x * 2 end
print(f(21))  -- 42

See Functions-Closures for full details.

---

userdata

Opaque C data managed by LuaLuaA lightweight, embeddable scripting language used as the primary scripting language in FiveM server development.. Two kinds:

• Full userdata: garbage-collected block allocated by LuaLuaA lightweight, embeddable scripting language used as the primary scripting language in FiveM server development.
• Light userdata: plain C pointer (not managed)

Userdata can have metatables to define behavior.

---

thread

Represents a coroutine. Not an OS thread — cooperative multitasking only.

See Coroutines for full details.

---

table

The sole data-structuring mechanism. Implements associative arrays.

local t = {}
t["key"] = "value"
t[1] = "first"
t.name = "Lua"     -- sugar for t["name"]

See Tables for full details.

---

Type coercion summary

From → To	string	number	boolean
number	tostring(n)	—	always truthy/falsy
string	—	tonumber(s) if numeric	always truthy/falsy
boolean	error (no auto)	error (no auto)	—
nil	error (no auto)	error (no auto)	falsy

[!warning] No implicit string↔number Lua 5.4LuaA lightweight, embeddable scripting language used as the primary scripting language in FiveM server development. removed implicit coercion between strings and numbers. "10" + 1 raises an error. Use tonumber("10") + 1.