Get the extension field from a declon-declon.
This is an ordinary field accessor created by fty::defprod.
Function:
(defun declon-declon->extension$inline (x) (declare (xargs :guard (declonp x))) (declare (xargs :guard (equal (declon-kind x) :declon))) (mbe :logic (b* ((x (and (equal (declon-kind x) :declon) x))) (bool-fix (car (cdr x)))) :exec (car (cdr x))))
Theorem:
(defthm booleanp-of-declon-declon->extension (b* ((extension (declon-declon->extension$inline x))) (booleanp extension)) :rule-classes :rewrite)
Theorem:
(defthm declon-declon->extension$inline-of-declon-fix-x (equal (declon-declon->extension$inline (declon-fix x)) (declon-declon->extension$inline x)))
Theorem:
(defthm declon-declon->extension$inline-declon-equiv-congruence-on-x (implies (declon-equiv x x-equiv) (equal (declon-declon->extension$inline x) (declon-declon->extension$inline x-equiv))) :rule-classes :congruence)
Theorem:
(defthm declon-declon->extension-when-wrong-kind (implies (not (equal (declon-kind x) :declon)) (equal (declon-declon->extension x) (bool-fix nil))))