計算機プログラムの構造と解釈[第2版]
(翔泳社)
ハロルド エイブルソン (著) ジュリー サスマン (著)
ジェラルド・ジェイ サスマン (著)
Harold Abelson (原著) Julie Sussman (原著)
Gerald Jay Sussman (原著) 和田 英一 (翻訳)
開発環境
計算機プログラムの構造と解釈[第2版](ハロルド エイブルソン (著)、ジュリー サスマン (著)、ジェラルド・ジェイ サスマン (著)、Harold Abelson (原著)、Julie Sussman (原著)、Gerald Jay Sussman (原著)、和田 英一 (翻訳)、翔泳社、原書: Structure and Interpretation of Computer Programs (MIT Electrical Engineering and Computer Science)(SICP))の第3章(標準部品化力、オブジェクトおよび状態)、3.3(可変データのモデル化)、3.3.3(表の表現)、局所表の作り方、問題3.26.を解いてみる。
その他参考書籍
- Instructor's Manual to Accompany Structure & Interpretation of Computer Programs
- プログラミングGauche (Kahuaプロジェクト (著), 川合 史朗 (監修), オライリージャパン)
- Scheme手習い
問題3.26.
コード(Emacs)
(begin
(define (print obj)
(display obj)
(newline))
(define (for-each proc . lists)
(define (exist-null? list-of-list)
(if (null? list-of-list)
#f
(let ((lst (car list-of-list)))
(if (null? lst)
#t
(exist-null? (cdr list-of-list))))))
(define (heads list-of-list)
(define (iter list-of-list)
(if (null? list-of-list)
'()
(let ((lst (car list-of-list)))
(if (not (pair? lst))
(display "error")
(cons (car lst)
(iter (cdr list-of-list)))))))
(if (or (null? list-of-list)
(exist-null? list-of-list))
'()
(iter list-of-list)))
(define (rests list-of-list)
(define (iter list-of-list)
(if (null? list-of-list)
'()
(let ((lst (car list-of-list)))
(if (not (pair? lst))
(display "error")
(cons (cdr lst)
(iter (cdr list-of-list)))))))
(if (or (null? list-of-list)
(exist-null? list-of-list))
'()
(iter list-of-list)))
(define (iter list-of-list)
(let ((args (heads list-of-list)))
(if (null? args)
'()
(begin (apply proc args)
(iter (rests list-of-list))))))
(if (null? lists)
(display "error")
(iter lists))
;; undefined
(if #f #f))
;; ((key . value) left right)
(define (make-table)
(let ((local-table '()))
(define (make-tree record left right) (list record left right))
(define (key tree) (caar tree))
(define (value tree) (cdar tree))
(define (left-branch tree) (cadr tree))
(define (right-branch tree) (caddr tree))
(define (lookup-iter k tree)
(cond ((null? tree) #f)
((= k (key tree)) (value tree))
((< k (key tree)) (lookup-iter k (left-branch tree)))
(else (lookup-iter k (right-branch tree)))))
(define (lookup k) (lookup-iter k local-table))
(define (insert-iter! k v tree)
(cond ((eq? tree '())
(set! local-table (make-tree (cons k v) '() '()))
'done)
((= k (key tree)) (set-cdr! (car tree) v)
'done)
((< k (key tree))
(if (null? (left-branch tree))
(set-car! (cdr tree) (make-tree (cons k v) '() '()))
(insert-iter! k v (left-branch tree)))
'done)
(else
(if (null? (right-branch tree))
(set-car! (cddr tree) (make-tree (cons k v) '() '()))
(insert-iter! k v (right-branch tree)))
'done)))
(define (insert! k value) (insert-iter! k value local-table))
(define (dispatch m)
(cond ((eq? m 'lookup-proc) lookup)
((eq? m 'insert-proc!) insert!)
(else (display "Unknown operation -- TABLE ")
(print m))))
dispatch))
(define operation-table (make-table))
(define get (operation-table 'lookup-proc))
(define put (operation-table 'insert-proc!))
(for-each
(lambda (pair)
(print (put (car pair) (cdr pair))))
(list (cons 5 'a) (cons 1 'b) (cons 4 'c) (cons 2 'd) (cons 3 'e)))
;; b d e c a #f
(for-each (lambda (n)
(print (get n)))
'(1 2 3 4 5 10))
(for-each
(lambda (pair)
(print (put (car pair) (cdr pair))))
(list (cons 5 'A) (cons 1 'B) (cons 4 'C) (cons 2 'D) (cons 3 'E)))
;; B D E C A #f
(for-each (lambda (n)
(print (get n)))
'(1 2 3 4 5 10))
)
入出力結果(Terminal(kscheme), REPL(Read, Eval, Print, Loop))
$ ./kscheme sample26.scm done done done done done b d e c a #f done done done done done B D E C A #f $
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