time

it may or may not be of interest to an individual, but LISP provides capability for timing the execution of arbitrary expressions. For instance, to time how long it takes to generate all the trees of order 6, one might execute the following.

CL-USER 2 > (time (generate-trees-of-order 6))
Timing the evaluation of (Generate-Trees-Of-Order 6)

user time    =      0.290
system time  =      0.440
Elapsed time =   0:00:03

...

CL-USER 3 >

APPENDIX B