rerouterator/fileWatchRoutine.lua

local lfs = require("lfs")

-- coroutine that watches files and calls the callback if they change
return function(filename, callback)
  lastUpdated = -1 --lfs.attributes(filename).modification
  while(true) do
    local newTime = lfs.attributes(filename).modification 
    if(newTime > lastUpdated) then
      callback(filename)
      lastUpdated = newTime
    end
    coroutine.yield()
  end
end