Enable logging for wai-servlet apps

[jneira]

• Currently there is no an easy, tested way to log from wai-servlet apps
• The appropriate features could be
  • work with the minimum possible configuration
  • integration with java logging, specially within servers
    • but avoiding the madness of java log frameworks
  • use of existing haskell libraries
• The options could be:
  • Make any of the existent haskell libraries work, maybe through a wrapper that integrates java logging
    • @NickSeagull has tested Network.Wai.Middleware.RequestLogger in wai-extra, that uses in turn fast-logger and it works if you use logStdOut
  • Create a new library, specific for eta to fulfill the features, in the spirit of clojure timbre
    • This could be a long time task
• Other useful links
  • https://stackoverflow.com/questions/6310961/how-do-i-do-logging-in-haskell
  • https://github.com/wdanilo/haskell-logger
  • http://hackage.haskell.org/package/hslogger
    • it can output Log4j's XMLLayout
  • https://hackage.haskell.org/package/katip