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• List-fix

Llist-fix

(llist-fix x) is locally just list-fix, but it is guarded with true-listp so that in the execution it is just an identity function.

This is very similar in spirit to functions like lnfix.

Note that list-fix already avoids consing in the case where x is a true-listp, but of course checking true-listp is linear in the length of the list, so llist-fix may save this overhead.

We leave this function enabled and always reason about list-fix instead.

Definitions and Theorems

Function: llist-fix$inline

(defun llist-fix$inline (x)
  (declare (xargs :guard (true-listp x)))
  (mbe :logic (list-fix x) :exec x))