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Previous: 2 Schemeの処理系
Schemeの仕様書は，4版のRevised
Report on
the Algorithmic Language Scheme，から，Revised
が出ています．
latex,texinfo,html形式で公開されていて，上記のFAQなどからたどることが
できます．
これらの仕様書には，後で説明する継続(continuation)の理論的根拠や
生まれてきた背景などが書かれています．
Schemeでは，Common Lispと同様の基本手続きが利用できます．
> 'a
a
> '#(a b c)
#3(a b c)
> '()
()
> '(+ 1 2)
(+ 1 2)
> '(quote a)
'a
> ''a
'a
> '"abc"
"abc"
> '13
13
> 145
145
> '#t
#t
> #t
#t
> (quote a)
a
> (quote #(a b c))
#(a b c)
>(quote (+ 1 2)
(+ 1 2)
> (+ 2 4)
6
> ((if #f + *) 3 4)
12
> ((lambda (x) (+ x x)) 4)
8
> (define reverse-subtract
(lambda (x y) (- y x)))
> (reverse-subtract 7 10)
3
> (define add4
(let ((x 4))
(lambda (y) (+ x y))))
> (add4 6)
10
> ((lambda x x) 3 4 5 6)
(3 4 5 6)
> ((lambda (x y . z) z) 3 4 5 6)
(5 6)
> (eq? '(a) '(a))
#f
> (equal? '(a) '(a))
#t
> (atom? '(a b))
#f
> (list? 10)
#f
> (list? ())
#t
> (list? '(a))
#t
> (pair? '())
#f
> (pair? '(a))
#t
> (symbol? '(a))
#f
> (symbol? 'a)
#t
> (number? 10)
#t
> (integer? 1.2)
#f
> (procedure? car)
#t
> (procedure? (lambda (x) (* x x)))
#t
> (procedure? '(lambda (x) (* x x)))
#f
> (not #t)
#f
> (not 3)
#f
> (not (list 3))
#f
> (not #f)
#t
>(cond ((> 3 2) 'greater)
((< 3 2) 'less))
greater
>(cond ((> 3 3) 'greater)
((< 3 3) 'less)
(else 'equal))
equal
> (case (* 2 3)
((2 3 5 7) 'prime)
((1 4 6 8 9) 'composite))
composite
> (case (car '(c d))
((a) 'a)
((b) 'b))
unspecified
> (case (car '(c d))
((a e i o u) 'vowel)
((w y) 'semivowel)
(else 'consonant))
consonant
> (and (= 2 2) (> 2 1))
#t
> (and (= 2 2) (< 2 1))
#f
> (and 1 2 'c '(f g))
(f g)
> (and)
#t
> (or (= 2 2) (> 2 1))
#t
> (or (= 2 2) (< 2 1))
#t
> (or #f #f #f)
#f
> (or (memq 'b '(a b c))
(/ 3 0))
(b c)
> (let ((x 2) (y 3))
(* x y))
6
> (let ((x 2) (y 3))
(let ((x 7)
(z (+ x y)))
(* z x)))
35
> (let ((x 2) (y 3))
(let* ((x 7)
(z (+ x y)))
(* z x)))
70
>(letrec ((even?
(lambda (n)
(if (zero? n)
#t
(odd? (- n 1)))))
(odd?
(lambda (n)
(if (zero? n)
#f
(even? (- n 1))))))
(even? 88))
#t
> (letrec ((even?
(lambda (n)
(if (zero? n)
#t
(odd? (- n 1)))))
(odd?
(lambda (n)
(if (zero? n)
#f
(even? (- n 1))))))
(even? 87))
#f
> (define x 0)
> x
0
> (begin (set! x 5)
(+ x 1))
6
> x
5
> (define x '(a b))
> (set! x '(1 2))
> x
(1 2)
> (set-car! x 5)
> x
(5 2)
> (begin (display "4 plus 1 equals ")
(display (+ 4 1)))
4 plus 1 equals 5>
> (do ((vec (make-vector 5))
(i 0 (+ i 1)))
((= i 5) vec)
(vector-set! vec i i))
#5(0 1 2 3 4)
>(let ((x '(1 3 5 7 9)))
(do ((x x (cdr x))
(sum 0 (+ sum (car x))))
((null? x) sum)))
25
> (map cadr '((a b) (d e) (g h)))
(b e h)
> (map (lambda (n) (expt n n)) '(1 2 3))
(1 4 27)
> (map + '(1 2 3) '(4 5 6))
(5 7 9)
> `(list ,(+ 1 2) 4)
(list 3 4)
>(let ((name 'a)) `(list ,name ',name))
(list a (quote a))
> `(a ,(+ 1 2) ,@(map abs '(4 -5 6)) b)
(a 3 4 5 6 b)
> `(( foo ,(- 10 3)) ,@(cdr '(c)) . ,(car '(cons)))
((foo 7) . cons)
> `#(10 5 ,(sqrt 4) ,@(map sqrt '(16 9)) 8)
#6(10 5 2 4 3 8)
> (apply + '(1 2 3))
6
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