(* To time a function (f: unit -> 'a), execute timeit f.
   The output is time spent in user mode, time spent in system mode, and time
   spent garbage collecting.  Add the three to get an honest total time.
   All times are in seconds. 
*)

fun timeit (f:unit ->'a) =
  let open Timer Time
      val cputimer = startCPUTimer()
      and realtimer = startRealTimer()
      val result = f()
      val realtime = checkRealTimer realtimer
      val cputimes = checkCPUTimer cputimer
  in print "u "; print (toString (#usr cputimes)); print "\t";
     print "s "; print (toString (#sys cputimes)); print "\t";
     print "gc "; print (toString (#gc cputimes)); print "\t";
     print "r "; print (toString realtime); print "\n";
     result
  end