Benchmark: timing 2500 iterations of grepGen, mapGen, smartGen...
   grepGen: 14 wallclock secs (13.70 usr +  0.00 sys = 13.70 CPU) @ 182.52/s (n=2500)
    mapGen: 13 wallclock secs (13.57 usr +  0.00 sys = 13.57 CPU) @ 184.20/s (n=2500)
  smartGen:  2 wallclock secs ( 1.19 usr +  0.00 sys =  1.19 CPU) @ 2107.93/s (n=2500)