tools.logging

My favorite example for this is the lame idiom you see in Java code: if (log.isDebugEnabled()) { log.debug("expensive" + debug + message); } This is "better" than just log.debug(...) because with the latter, your expensive log message argument needs to be evaluated even if debug is disabled. However, in a language w/ macros, you just say: (debug (str "expensive" debug message)) and these considerations are already taken care of for you: https://github.com/clojure/tools.logging/blob/master/src/mai...

A good example, clojure logging. https://github.com/clojure/tools.logging They look the same as normal logging function calls, but entirely avoid the issue of "logging guards." I'll point you at a good link, but basically if you have a lot of calls to logger.debug, logger.trace, etc, and they involve a lot of string conversions, you pay the penalty for those string conversions all the time even when you're logging at warn or higher. This leads many java developers to do the following: if (LOGGER.isDebugEnabled()) { LOGGER.debug("last node was: " + node); } ... which makes logging significantly heavier visually. With a macro you are essentially adding syntax, so you can bake the guards into your log statements. Logging guards: http://www.kdgregory.com/index.php?page=java.logging

I'm not sure if clojure's tools.logging helps or hurts in this regard. It adds another layer to the onion, though with the aim of leveraging macros' non-evaluation of the logging args. http://github.com/clojure/tools.logging