A string describing the reason that the process is waiting.
A function designator.
The arguments that wait-function is applied to.
The function
process-wait
suspends the current Lisp process until the predicate
wait-function
applied to
wait-arguments
returns
t
. This is tested periodically.
wait-function has several limitations: it must not do a non-local exit, it should not have side effects and (since it is called frequently) it should be efficient.
wait-reason allows you to find out why a process is waiting via the function process-whostate.
LispWorks User Guide and Reference Manual - 21 Dec 2011