Documentation

Note a significant event, state transition, status, or debugging message. This:

    event "Starting..."

will result in

13:05:55Z (0000.001) Starting...

appearing on stdout and the message being sent down the logging channel. The output string is current time in UTC, and time elapsed since startup shown to the nearest millisecond (our timestamps are to nanosecond precision, but you don't need that kind of resolution in in ordinary debugging).

Messages sent to syslog will be logged at Info level severity.

Output a debugging message formed from a label and a value. This is like event above but for the (rather common) case of needing to inspect or record the value of a variable when debugging code. This:

    setProgramName "hello"
    name <- getProgramName
    debug "programName" name

will result in

13:05:58Z (0003.141) programName = hello

appearing on stdout and the message being sent down the logging channel, assuming these actions executed about three seconds after program start.

Messages sent to syslog will be logged at Debug level severity.

Convenience for the common case of needing to inspect the value of a general variable which has a Show instance

Convenience for the common case of needing to inspect the value of a general variable for which there is a Render instance and so can pretty print the supplied argument to the log. This will pass the detected terminal width to the render function, resulting in appopriate line wrapping when rendering your value (if logging to something other than console the default width of 80 will be applied).