Get the start field from a span.
This is an ordinary field accessor created by fty::defprod.
Function:
(defun span->start$inline (x) (declare (xargs :guard (spanp x))) (declare (xargs :guard t)) (let ((__function__ 'span->start)) (declare (ignorable __function__)) (mbe :logic (b* ((x (and t x))) (position-fix (cdr (std::da-nth 0 x)))) :exec (cdr (std::da-nth 0 x)))))
Theorem:
(defthm positionp-of-span->start (b* ((start (span->start$inline x))) (positionp start)) :rule-classes :rewrite)
Theorem:
(defthm span->start$inline-of-span-fix-x (equal (span->start$inline (span-fix x)) (span->start$inline x)))
Theorem:
(defthm span->start$inline-span-equiv-congruence-on-x (implies (span-equiv x x-equiv) (equal (span->start$inline x) (span->start$inline x-equiv))) :rule-classes :congruence)