Defchoose-strengthen
Value of the :strengthen option
of a function introduced via defchoose.
- Signature
(defchoose-strengthen fn wrld) → t/nil
- Arguments
- fn — Guard (defchoose-namep fn wrld).
- wrld — Guard (plist-worldp wrld).
- Returns
- t/nil — A booleanp.
If explicitly supplied, the value of the :strengthen option
is the last element of the defchoose event,
which consists of seven element in this case.
If not explicitly supplied,
the value of the :strengthen option is nil,
and the defchoose event consists of five elements only.
Definitions and Theorems
Function: defchoose-strengthen
(defun defchoose-strengthen (fn wrld)
(declare (xargs :guard (and (plist-worldp wrld)
(defchoose-namep fn wrld))))
(let ((__function__ 'defchoose-strengthen))
(declare (ignorable __function__))
(let ((event (get-event fn wrld)))
(if (= (len event) 5)
nil
(car (last event))))))
