Add some helpers

[winterland1989]

I'd like to add following enhancements:

• generalise ApacheLoggerActions from wai-logger to something like FastLoggerActions with configurable auto-rotate and auto-log-timestamp capabilities, add these to fast-logger.

Motivation: timestamp logging is absolutely necessary, a lot of librarys doing this in a very inefficient way, for example, logging doing this with a system call and a directly show. The work you have done in wai-logger is awesome!

• add runFastLoggerLoggingT :: MonadIO m => FastLoggerActions -> LoggingT m a -> m a to monad-logger and re-export FastLoggerActions related functions from fast-logger.

Motivation: since monad-logger rely on fast-logger, we should provide ways to use it with MonadLogger.

Are these changes look good to you? I'd like send a pr with those enhancement : )

[winterland1989]

B.T.W, is there any reason not to update date-cache package with auto-update implementation?

[kazu-yamamoto]

Please give us pull request to show your code.

Michael maintains monad-logger while I maintain fast-logger and wai-logger. Please separate your pull requests for each maintainer. If you mix up, the review process gets harder.

[kazu-yamamoto]

B.T.W, is there any reason not to update date-cache package with auto-update implementation?

date-cache is obsoleted. Warp has date cache by itself now.

[winterland1989]

A side note: should we make a global simpleTimeCacher? My preference is not but I really need some input here.

[kazu-yamamoto]

Does the global time cacher stay always even in the case where date is not necessary?

[winterland1989]

Does the global time cacher stay always even in the case where date is not necessary?

That depend on how auto-update implement cache, from what i read from yesodweb/wai#351, cacher will be auto turned off if user don't read it frequently enough.

[kazu-yamamoto]

Yes, you are right.

[winterland1989]

Ok, i will add a global simpleTimeCacher to encourage user share cache between loggers, and refract wai-logger based on this. PR will come soon.