Check if a value of type
Function:
(defun boolean-from-schar (x) (declare (xargs :guard (and (scharp x)))) (/= (integer-from-schar x) 0))
Theorem:
(defthm booleanp-of-boolean-from-schar (booleanp (boolean-from-schar x)))
Theorem:
(defthm boolean-from-schar-of-schar-fix-x (equal (boolean-from-schar (schar-fix x)) (boolean-from-schar x)))
Theorem:
(defthm boolean-from-schar-schar-equiv-congruence-on-x (implies (schar-equiv x x-equiv) (equal (boolean-from-schar x) (boolean-from-schar x-equiv))) :rule-classes :congruence)