LUA-INTRO.md

Variables and typing

variable = value  
local a = 10  
b = true  
c = false  
d = nil  
e, f, g = 5, "hello", 6.1  

Operators

or
and
<  >  <=  >=  ~=  ==  ..
+  -
*  /  %
not   #   -
^

Conditional loops

while i <= 5 do
end

repeat
  break
until i > 10

for i = 1, 10, 2 do
end

Functions

function dothis()
  local x, y = dothat(4, 5)
  return x^y
end

function dothat(a1, a2)
  return a1*2, a2*3
end

Tables

x = 5
a = {}
b = {sl1 = x, sl2 = 3}

a[1] = 20

print(a[1])

Strings

s = "Software Circus"
print(#s) -- 15

t = "123" .. 4 .. "56"

Numbers and calculations

a = 3.1415926
b = a * 2

c = node.random() -- 0..1
d = node.random(10) -- 1..10

Files

file.open("values.txt")
file.write(1)
file.write(2)
file.writeln(3)
file.close
file.open("othervalues")
a = {}
a = file.readline()
file.close()

Input and output

gpio.mode(1, gpio.INPUT,
  gpio.PULLUP)
if gpio.read(1) then
  print("high")
else
  print("low")
end
print(adc.read(0))

Timers and events

tmr.delay(1000)
start = tmr.now()

tmr.alarm(0, 1000,
  tmr.ALARM_AUTO,
  function()
    print("hallo")
  end)