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• Std/lists
• Nthcdr

Rest-n

rest-n is identical to nthcdr, but its guard does not require (true-listp x).

Reasoning Note. We leave rest-n enabled, so it will just get rewritten into nthcdr. You should typically never write a theorem about rest-n: write theorems about nthcdr instead.

Definitions and Theorems

Function: rest-n

(defun rest-n (n x)
       (declare (xargs :guard (natp n)))
       (mbe :logic (nthcdr n x)
            :exec (cond ((zp n) x)
                        ((atom x) nil)
                        (t (rest-n (- n 1) (cdr x))))))