3 main parts:
Intro
Feel
Applications
Part 1: Intro
Roberto Ierusalimschy
Lua is portable, powerful, embeddable & fast.
Embeddable
General purpose language
Embedable language
Portable
Portable
⇒ C99
Small
Small
git clone https://github.com/LuaDist/lua.git
cloc lua/src
⇒ ~ 15k (C99)
Small
git clone https://github.com/LuaDist/lua.git
cloc lua/src
⇒ ~ 200KB compiled
Implementations
Lua (5.1, 5.2, 5.3)
LuaJIT
eLua
...
Part 2: Feel
Learn Lua in 15 minutes
local name = 'Peter'
local age = 35
local genter = "male"
print(name .. " is a " .. age .. ' years old ' .. gender)
local multilineString = [[
Lorem ipsum
dolor sit amet
]]
-- a single-line Lua comment
--[[
a multi-line comment in Lua
]]
Functions
-- Function declaration
local function sum(a,b)
return a + b
end
print(sum(3,2)) -- 5
Functions
-- Almost the same as before
local sum = function(a,b)
return a + b
end
print(sum(3,2)) -- 5
Conditionals
local function isEven(n)
if n % 2 == 0 then
return true
end
return false
end
print(isEven(5)) -- false
Conditionals
local function isEven(n)
return n % 2 == 0
end
print(isEven(5)) -- false
Arrays & Numeric Loop
local a = {'a', 'b', 'c', 'd'}
print(a[1]) -- a
local length = #a
for i = 1, length do
print(a[i])
end
While loop
local a = {'a', 'b', 'c', 'd'}
print(a[1]) -- a
local length = #a
local i = 1
while i < length do
print(a[i])
i = i + 1
end
Repeat until loop
local a = {'a', 'b', 'c', 'd'}
print(a[1]) -- a
local length = #a
local i = 1
repeat
print(a[i])
i = i + 1
until i > length
Hashes / Objects
local person = {name = 'peter', age = 21}
print(person['name']) -- peter
print(person.name) -- also peter
for key,value in pairs(person) do
print(key .. ' => ' .. value)
end
--[[
name => peter
age => 21
]]
Hash, Array == Table
local a = {'a', 'b', 'c', 'd'}
local person = {name = 'peter', age = 21}
print(a[1])
print(person['name'])
print(type(a)) -- table
print(type(person)) -- table
Reuse
Lua tables:
- Arrays
- Hashes
- Structs
- Objects
- References
- Environments
Lua functions:
- Values
- Blocks
- Scopes
- Iterators
- Generators
Types (~7)
string, number, table, boolean, function, thread, nil
Libraries (~7)
string, math, table, os, io, coroutine, debug
Built-in functions (~30)
assert load pcall setmetatable
collectgarbage loadfile print tonumber
dofile loadstring rawequal tostring
error module rawget type
rawset xpcall getfenv next
unpack getmetatable require select
ipairs pairs setfenv
Libraries
luarocks.org
rocks.moonscript.org
~700 rocks
Lua feels like
A faster, smaller, better javascript
// Very little of this stuff:
[9,10,1,2].sort()
> [1,10,2,9]
Part 3: Applications
Key-value data store
require "redis"
redis = Redis.new('localhost', 6379)
redis.set("name", "peter")
name = redis.get("name") # "peter"
redis.set("age", "25")
new_age = redis.incr("age") # 26
Concurrent, but single threaded
counter = redis.get('counter')
redis.incr('counter') if counter.is_number?
counter = redis.get('counter')
########## Multithreading ##########
redis.incr('counter') if counter.is_number?
lua_code =
%{
local counter = redis.call("GET", KEYS[1])
if type(tonumber(counter)) == "number" then
return redis.call("INCR", KEYS[1])
end
}
redis.eval(lua_code, ["counter"])
brew install vim --with-lua
-or-
brew install macvim --with-lua
Startup Speed
Vim script 0 1.498s
Python 0.0166s 0.027s (2000%)
Lua(jit) 0.0002s 0.001s (1152000%)
Corona SDK
coronalabs.com/i-want-to-build/games/
coronalabs.com/i-want-to-build/business-apps/
nginx.conf:
http {
server {
location /hello {
content_by_lua_file 'hello.lua'
}
}
}
hello.lua:
local name = ngx.var.arg_name or "Anonymous"
ngx.say("Hello, ", name, "!")
Example:
$ curl http://localhost/hello?name=peter
# Hello, peter!
return function(req, next_middleware)
req.headers['Authorization'] = 'My Secret'
return next_middleware()
end
return function(req, next_middleware)
local res = next_middleware()
res.body = 'Hodor'
return res
end
Conclusion
