Suspends the current process until a condition is true.
A string describing the reason that the process is waiting.
A function designator.
The arguments that
is applied to.
suspends the current Lisp process until the predicate
. This is tested periodically.
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.
allows you to find out why a process is waiting via the function process-whostate.
LispWorks User Guide and Reference Manual - 21 Dec 2011