Spoiler: LISP is useless

Name one noteworthy program that was coded in LISP.

I'll wait.

Did a bit of refactoring over the last version, looks a bit better to me, but it's hard to get it reach the Haskell version's terseness without defining a specific DSL.


(defun seq (n m)
  (loop for i from n to m collect i))

(defun singlep (list)
  (and (consp list) (null (cdr list))))

(defun compute-graph
    (removal-order &optional (n (+ 2 (length removal-order))))
  (let ((vertex-bag (seq 1 n)))    
    (mapcon #'(lambda (order)
                (labels ((get-next-edge (to)
                           (cons
                            (let ((next-vertex
                                   (first (sort (set-difference vertex-bag order) #'<))))
                              (setf vertex-bag (remove next-vertex vertex-bag))
                              next-vertex)
                            to)))
                  (let ((before-last-vertex (first order)))
                    (if (singlep order)                       
                        (list #1=(get-next-edge before-last-vertex) #1#)
                        (list #1#)))))
            removal-order)))