Lua snippet

coroutine.lua

--- http://www.lua.org/pil/9.html                                                                        

function producer()
   return coroutine.create(
      function()
         while true do
            local v = io.read()
            coroutine.yield(v)
            if not v then break end
         end
      end)
end

function consumer(prod)
   while true do
      local state, v = coroutine.resume(prod)
      if not v then break end
      io.write(v, "\n")
   end
end

p = producer()
consumer(p)

iterator.lua

function fib_closure()
  local a = 1
  local b = 1
  return function()
    local v = a
    a, b = b, b + v
    return v
  end
end

function fib_ite_expand ()
   local a = 1
   return function (_, b)
      v, a = a, b
      return (v + b), v
   end, nil, 1
end

function fib_stateless()
   local state = {a = 1, b = 1}
   return function (st)
      v = st.a
      st.a, st.b = st.b, st.b + v
      return v
   end, state
end