Extras

This repository contains some sample Lua programs and extra code and tools for Lua.

All files are distributed under this license.

Code and tools

noparser.c

Lua core without the parsing modules
5.5 · 5.4 · 5.3 · 5.2

one.tar.gz

Lua core, libraries, and interpreter in a single file
5.5 · 5.4 · 5.3 · 5.2

strict.lua

checks uses of undeclared global variables
5.4 · 5.3 · 5.2 · 5.1

Sample Lua programs

Here are some sample Lua programs. You can try them online.

hello.lua copy show

The first program in every language

-- the first program in every language

io.write("Hello world, from ",_VERSION,"!\n")

account.lua copy show

A simple example of OOP in Lua

-- from PiL 1, Chapter 16

Account = {balance = 0}

function Account:new (o, name)
  o = o or {name=name}
  setmetatable(o, self)
  self.__index = self
  return o
end

function Account:deposit (v)
  self.balance = self.balance + v
end

function Account:withdraw (v)
  if v > self.balance then error("insufficient funds on account "..self.name) end
  self.balance = self.balance - v
end

function Account:show (title)
  print(title or "", self.name, self.balance)
end

a = Account:new(nil,"demo")
a:show("after creation")
a:deposit(1000.00)
a:show("after deposit")
a:withdraw(100.00)
a:show("after withdraw")

-- this would raise an error
--[[
b = Account:new(nil,"DEMO")
b:withdraw(100.00)
--]]

bisect.lua copy show

Solving non-linear equations with the bisection method

-- bisection method for solving non-linear equations

delta=1e-6	-- tolerance

function bisect(f,a,b,fa,fb)
 local c=(a+b)/2
 io.write(n," c=",c," a=",a," b=",b,"\n")
 if c==a or c==b or math.abs(a-b)<delta then return c,b-a end
 n=n+1
 local fc=f(c)
 if fa*fc<0 then return bisect(f,a,c,fa,fc) else return bisect(f,c,b,fc,fb) end
end

-- find root of f in the inverval [a,b]. needs f(a)*f(b)<0
function solve(f,a,b)
 n=0
 local z,e=bisect(f,a,b,f(a),f(b))
 io.write(string.format("after %d steps, root is %.17g with error %.1e, f=%.1e\n",n,z,e,f(z)))
end

-- our function
function f(x)
 return x*x*x-x-1
end

-- find zero in [1,2]
solve(f,1,2)

globals.lua copy show

Show all global variables

-- show all global variables

local seen={}

function dump(t,i)
	seen[t]=true
	local s={}
	local n=0
	for k in pairs(t) do
		n=n+1 s[n]=k
	end
	table.sort(s)
	for k,v in ipairs(s) do
		print(i,v)
		v=t[v]
		if type(v)=="table" and not seen[v] then
			dump(v,i.."\t")
		end
	end
end

dump(_G,"")

sieve.lua copy show

The sieve of Eratosthenes with coroutines

-- the sieve of Eratosthenes programmed with coroutines
-- typical usage: lua -e N=500 sieve.lua | column

-- generate all the numbers from 2 to n
function gen (n)
  return coroutine.wrap(function ()
    for i=2,n do coroutine.yield(i) end
  end)
end

-- filter the numbers generated by `g', removing multiples of `p'
function filter (p, g)
  return coroutine.wrap(function ()
    for n in g do
      if n%p ~= 0 then coroutine.yield(n) end
    end
  end)
end

N=N or 500		-- from command line
x = gen(N)		-- generate primes up to N
while 1 do
  local n = x()		-- pick a number until done
  if n == nil then break end
  print(n)		-- must be a prime number
  x = filter(n, x)	-- now remove its multiples
end

Last update: Fri Dec 26 11:31:49 UTC 2025