lispm

(defun make (pts &key closed)
  (let ((n (length pts)))
    (if (< n 4) (error "must have at least 4 pts."))
    (let ((apts (make-dfloat-array n)))
      (loop
        for p in pts
        for i from 0
        do
          (destructuring-bind (x y)
            p

lispm

(defun psymb (package &rest args)
  (values (intern (apply #'mkstr args) package)))



(defmacro with-struct ((name . fields) struct &body body)
  (let ((gs (gensym)))
    `(let ((,gs ,struct))
       (let ,(mapcar #'(lambda (f)

lispm

; https://stackoverflow.com/a/25264944/69545

; ================================================================
; This is the usual evolution

; 1) simple recursive version
; 2) more efficient tail-recursive version
; 3) efficient loop

lispm

;see https://stackoverflow.com/questions/46496083/lazily-generating-prime-in-common-lisp/46497515#46497515

(defun divisor-in-list (n list)
  (some (lambda (i)
          (zerop (rem n i)))
        list))

(defun primes ()
  (let ((p (list 2))
        (n 2))

lispm

; the hashtable is found on the binding stack

(defmacro memo (v e &aux (§v (gensym "V")))
  `(locally (declare (special *mem*))
     (let ((*mem* (or (and (boundp '*mem*) *mem*)
                      (make-hash-table)))
           (,§v ,v))
       (declare (special *mem*))
       (or (gethash ,§v *mem*)
           (setf (gethash ,§v *mem*) ,e)))))

lispm

; https://github.com/inconvergent/snek/blob/master/utils/count.lisp

(defun make-counter (&optional ll)
  (let ((c (make-hash-table :test #'equal)))
    (loop for a in ll do (counter-add c a))
    c))

(defun counter-add (c a)
  (incf (gethash a c 0)))

lispm

; https://github.com/inconvergent/snek/blob/master/utils/spline-script.lisp

(defun test-centroids (counts nc ncn)
  (loop for i from 0 below nc
        always (multiple-value-bind (val exists)
                   (gethash i counts)
                 (and exists (>= val ncn)))))

lispm

<GLS is Guy Steele, RMS is Richard Stallman, DLW is Dan Weinreb, Moon is David Moon, Ed is Ed
Schwalenberg, CBF is Charles Frankston, EAK is Earl Killian, ECC is Gene Cicarelli,
RMF is Bob Frankston, and JLK is John Kulp.>

---

I think all of us have been relying on our memories, which can
fail in various ways. Last time around I checked my file folder
of notes about Emacs, which has some useful information, but
not a lot about who did what. Now I have some more information

lispm

(defun divisors (n &aux (divisors (list 1)))
  (etypecase n
    ((integer * 1) nil)
    ((integer 2 *)
     (loop with q and r
           for i from 2 to (isqrt n)
           do (setf (values q r) (truncate n i))
           when (zerop r) do (push q divisors) and do (push i divisors))
     (if (and (second divisors)
              (= (first divisors) (second divisors)))

lispm

; John McCarthy. Puzzle Solving Program in LISP. Memo 20, Artificial Intelligence Project
; http://www.bitsavers.org/pdf/mit/ai/aim/AIM-020.pdf
; 1960

; Common Lisp translation: Rainer Joswig, 2016, [email protected]
; basically the code is unchanged, but using s-expression syntax in Common Lisp

(defparameter pzl
  '((a1  (a2 a5)              7.5)
    (a2  (a1 a5 a9 a3)        3.5)