A cron-like scheduler with sane DSL

(job "Say 'Hi' all the time" every 5.seconds (print "Hi"))

(job "Compose and send monthly report"
     every 1.month (send-report (compose-monthly-report)))

If you want to see it with your eyes, make sure to load the following code:

(defun write-to-file (msg file)
  (with-open-file (log file
                       :direction :output
                       :if-exists :append
                       :if-does-not-exist :create)
    (format log "~A~%" msg)))

(job "Print farbe" every 3.seconds (write-to-file "Farbe" "log.txt"))
(job "Print colour" every 2.seconds (write-to-file "Colour" "log.txt"))
(job "Print @@@@ 1 min @@@@@" every 1.minute
       (write-to-file "@@@@@@ 1 min @@@@@@" "log.txt"))

Now, after (clerk:start), tailing log.txt should give you something like this:

Colour
Farbe
Colour
Colour
Farbe
Colour
Farbe
Colour
Colour
Farbe
Colour
/one minute later.../
@@@@@@ 1 min @@@@@@
/etc.../

The original idea was for users to use the library to execute some sort of execution of a configuration file. However you can use the job creation process programatically with the underlying function job-fn. E.g.:

(defparameter *query-interval* 5)
(job-fn (format nil "Query the API every ~A seconds" *query-interval*)
        'every
        `(,*query-interval* seconds)
        #'query-api-fn)

As you can see, you have to provide a function (either anonimous function or a function symbol) as the last argument.

Clone the repo inside quicklisp/local-projects and do (ql:quicklisp :clerk) in your REPL.

Make sure your jobs are loaded before executing (clerk:start). The jobs reside inside clerk:*jobs*, but you can also type (clerk:calendar) to see a list of all scheduled and running jobs.

There are two types of jobs - continuous and one-time. If a job has the keyword every after the job description - the job will be countinuous. This means that when an event is fired, a new event will be pushed in the event queue for firing exactly interval time from now. The jobs above are an example for continuous jobs.

A one-time job is fired once and then it is removed from the jobs' queue. An example for a one-time job can be:

(job "Extraordinary event" in 5.days (send-mail "Don't forget X"))

You can use any word instead of in.

Right now (more are coming soon) there are 2 type of intervals:

1. Numbered intervals

[number].[interval-type]

where the number is a positive integer and the interval-type if one of the following: second, minute, hour, day, week, month, year. Also you can use the plural form of all these words. For example 1.second and 2.seconds are both valid.

2. Days of the week

(job "Weekly report" every monday (create-report))

Pretty self-explanatory. The idea is that if you type the day of the week, clerk will calculate when it is and add an event to the queue.

If you have issues - open a github issue or contact me at (reverse "moc.liamg@vokist"). If you want to contribute - open an issue or make a PR. Thanks!