Scheme手習いメモ (3章 - 偉大なるCons) ref: https://qiita.com/iizukak/items/630ffe8dc5f350cccc7e

file3.txt

(define multirember
  (lambda (a lat)
    (cond
      ((null? lat) (quote ()))
      (else
        (cond
          ((eq? (car lat) a)
           (multirember a (cdr lat)))
          (else (cons (car lat)
                      (multirember a
                                   (cdr lat)))))))))

(define a 'cup)
(define lat '(coddee cup tea cup and hick cup))
(print (multirember a lat))

firsts.scm

(define firsts
  (lambda (l)
    (cond
      ((null? l) quote ())
      (else (cons (car (car l))
                  (firsts (cdr l)))))))

(print (firsts '((a b) (b c) (d e))))

insertR.scm

(define insertR
  (lambda (new old lat)
    (cond
      ((null? lat) (quote ()))
      (else (cond
              ((eq? (car lat) old)
               (cons old
                     (cons new (cdr lat))))
              (else (cons (car lat)
                          (insertR new old
                                   (cdr lat)))))))))

(define new 'topping)
(define old 'fudge)
(define lat '(ice cream with fudge for dessert))
(print (insertR new old lat))

multisubset.scm

(define multisubset
  (lambda (new old lat)
    (cond
      ((null? lat) (quote ()))
      (else
        (cond
          ((eq? (car lat) old)
           (cons new
                 (multisubset new old
                              (cdr lat))))
          (else (cons (car lat)
                      (multisubset new old
                                   (cdr lat)))))))))


(define old 'fudge)
(define new 'topping)
(define lat '(fudge cream with fudge for dessert))
(print (multisubset new old lat))

rember.scm

(define rember
  (lambda (a lat)
    (cond
      ((null? lat) (quote ()))
      ((eq? (car lat) a) (cdr lat))
      (else (cons (car lat)
                  (rember a (cdr lat)))))))

(define a 'and)
(define lat '(bacon and potatos))
(print (rember a lat))