I am writing a new application and am interested in logging as one way of
debugging it.  I also might like to gather information about how the
application is used.

I found an old blog post that suggested happstack applications should log
using hslogger, aka System.Log.Logger.  This requires an IO action, which
is fine, but I am wondering if anyone here has ideas about best practices
for logging using combinators.  I would rather not just drop down log calls
everywhere; it feels too much like C programming.  I figure with
higher-order functions there must be a better way to manage logging.  Any
ideas?

Unrelated, but I posted a new comment on your SO question (duno if you get
a notice for that? I didn't for your comment.):

http://stackoverflow.com/questions/12047656/can-a-session-cookie-be-s...

As for logging, hslogger is used by default for logging requests in
Happstack, but it's just a default if you use nullConf and not a hard
requirement. For Happstack 8 hslogger will most likely be replaced with
something else. So for your own logging you can use whatever, although if
you're using the hslogger setup for request logging it might be neat to be
able to configure all logging together, with a single package. Not sure
what kind of logging combinators you're looking for, though? For debugging
it might be more useful to use things like traceStack/+RTS -xc, and compile
with -prof -fprof-auto (assuming GHC 7.4+). This produces stack traces
similar to those in other languages. Or are you looking for something else
entirely?

On Fri, Aug 24, 2012 at 2:21 AM, Norman Ramsey <fellswal...@gmail.com>wrote:

For debugging, I have user Debug.Trace which I find very practical. It
might be a lot like C programming though, but I think this might be less of
a problem if you use it for debugging only and use a different, more
Haskell-y, way of  logging for other purposes.

2012/8/24 Norman Ramsey <fellswal...@gmail.com>

I should clarify that I'm perfectly good using QuickCheck and Debug.Trace
as needed during development.
But during *deployment* I want some logging going on so that if something
strange happens, there will be bread crumbs.