Re: Rules engine in Lua?

[Fabien <fleutot+lua@...>]

There is a state machine extension under development for metalua 0.4. It lets you write things like this:

-{ extension 'machine' }

machine M
  state init
    when exit do print "Machine M is starting" end
    on START -> State1
  state State1
    when enter do
      print "do whatever you want in this Lua block"
      print "it will be evaluated every time the machine enters state S1"
    end
    on SOME_MSG -> State2 
  state State2
    do
      print "there's no explicit 'when' before this action block;"
      print "It's run when entering and updating the state by default"
    end
    on SOME_OTHER_MSG, OR_YET_ANOTHER_MSG -> State1
 end

M 'START' -- starts the machine, transitions it from state init to State1

(not seriously tested yet, probably doesn't work on metalua 0.3).

http://repo.or.cz/w/metalua.git?a=blob;f=src/lib/extension-compiler/machine.mlua
http://repo.or.cz/w/metalua.git?a=blob;f=src/lib/extension-runtime/machine.lua