lispm

;;; L-99: Ninety-Nine Lisp Problems

;; Problem 9: Pack consecutive duplicates of list elements into sublists.

; If a list contains repeated elements they should be placed in separate sublists.
;
; Example:
;
; * (pack '(a a a a b c c a a d e e e e))
; ((A A A A) (B) (C C) (A A) (D) (E E E E))

lispm

; Original Version from Atabey Kaygun, Conjugate Partitions
; http://kaygun.tumblr.com/post/145269023094/conjugate-partitions

; Derived versions: Rainer Joswig, [email protected], 2016

; version 1 using LOOP

(defun dual (xs &aux k n r)
  (loop while xs do
        (setf k  (reduce #'min xs)

lispm

(defun make-vars (vars &aux syms)
  (values (loop for var in vars
                if (eq var NIL)
                collect (let ((sym (gensym "ignore"))) (push sym syms) sym)
                else collect var)
          syms))

(defmacro multiple-value-bind-some (vars form &body body)
  (multiple-value-bind (vars syms) (make-vars vars)
    `(multiple-value-bind ,vars ,form

lispm

;;; http://xen.garden/wp/?p=25

; Common Lisp version by Rainer Joswig, [email protected], 2016

(defun create-symbol (prefix suffix)
  (intern (format nil "~a-~a" prefix suffix)
          (symbol-package suffix)))

(defun make-get-set (name
                     &aux

lispm

; Hi and welcome to team Gilded Rose. As you know, we are a small inn
; with a prime location in a prominent city ran by a friendly
; innkeeper named Allison. We also buy and sell only the finest goods.
; Unfortunately, our goods are constantly degrading in quality as they
; approach their sell by date. We have a system in place that updates
; our inventory for us. It was developed by a no-nonsense type named
; Leeroy, who has moved on to new adventures. Your task is to add the
; new feature to our system so that we can begin selling a new
; category of items.
; First an introduction to our system:

lispm

(defun diamond (letter)
  (labels ((letter-value (letter)
             (- (char-code (char-downcase letter))
                (char-code #\a)))
           (pad-char (char n)
             (loop repeat n do (write-char #\space))
             (write-char char))
           (write-letter-line (letter front back)
             (pad-char letter front)
             (unless (zerop back)

lispm

; John McCarthy. Puzzle Solving Program in LISP. Memo 20, Artificial Intelligence Project
; ftp://publications.ai.mit.edu/ai-publications/pdf/AIM-020.pdf
; 1960

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

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

lispm

; page 13, Ralf Hinze, Einführung in die funktionale Programmierung mit Miranda

#|

take' 0 x = []
take' (n+1) [] = []
take' (n+1) (a:x) = a : take' n x

; The ugly Scheme version in the book
(define take

lispm

(defun split-with (pred list)
  "splits the LIST at the first NIL result of PRED" 
  (values (loop while (and (not (null list))
                           (funcall pred (first list)))
                collect (pop list))
          list))

(defun map-while (predicate function list)
  (loop with e
        while (not (null list))

lispm

; https://www.reddit.com/r/dailyprogrammer/comments/3irzsi/20150828_challenge_229_hard_divisible_by_7/

(defun lucky7s (n &aux
                  (nx0 (floor (+ n 2) 3))
                  (ny0 (floor (+ n 1) 3))
                  (nz0 (floor n       3))
                  (cache (make-hash-table :test 'equal)))
  (labels ((nt (k m &aux (n 0) (t0 0) nsub tsub)
             (cond ((zerop m)
                    (values (if (zerop k) 1 0) 0))