A continuation is like a savepoint, representing "what's left to run" at a given time.

I am using them in a real life application. I am calculating the available tables for a full calendar with many time slots and with respect to many configurable business rules for restaurants. Using callcc this feature got blazingly fast and very nicely readable. Also we use it to optimise table arrangements with respect to complex restaurant business rules (even something like: Guest A doesn't like to sit near Guest B). Please just have a look at these resources: https://github.com/chikamichi/amb/tree/master/examples http://web.archive.org/web/20151116124853/http://liufengyun.chaos-lab.com/prog/2013/10/23/continuation-in-ruby.html Please help me to keep Guest A away from Guest B. Bad things might happen.

This (somewhat contrived) example allows the inner loop to abandon processing early: callcc {|cont|   for i in 0..4     print "\n#{i}: "     for j in i*5...(i+1)*5       cont.call() if j == 17       printf "%3d", j     end   end }