logging is a wrapper around fast-logger which makes
it easy to log from IO. It provides the following conveniences on top of
those libraries:
A set of shorter functions to type: debug, log, warn, plus others
that flush after each message, or which allow providing a message source
string.
Logging variants of error, trace and traceShow, called errorL,
traceL and traceShowL. These use unsafePerformIO in order to act as
direct replacements, so the usual caveats apply.
A global function, setDebugLevel, which uses a global IORef to record
the logging level, saving you from having to carry around the notion of
"verbosity level" in a Reader environment.
A set of "timed" variants, timedLog and timedDebug, which report how
long the specified action took to execute in wall-clock time.
