基本的な関数
CAR
==> (car '(a b c d e))
a
==> (car '(1 2 3))
1
==> (car '((a b) c))
(a b)
==> (car 'a)
ERROR
CDR
==> (cdr '(a b c d e))
(b c d e)
==> (cdr '(1 2 3))
(2 3)
==> (cdr '((a b)))
==> (cdr 'a)
ERROR
CADR (cadr ...) = (car (cdr ...))
==> (cadr '(a b c d e))
b
==> (cadr '(1 2 3))
2
==> (cadr '((a b) c))
c
==> (cadr '(a))
ERROR
CDAR, CAAR, CDDR, CAAAR,...等についても同様．
CONS
==> (cons 'a 'b)
(a . b)
==> (cons 'a '(b))
(a b)
==> (cons '(a b) '(c d))
((a b) c d)
==> (cons 'a (cons 'b 'c))
(a b . c)
EQ?
;2つのセル同士，あるいはポインタを比べるにはeq?
を用いる
==> (eq? 'a 'b)
#f
==> (eq? 'a 'a)
#t
==> (eq? 1 1)
#t (implementation dependent)
==> (eq? '(a) '(a))
#f
==> (define x '(a b))
==> (define y (cdr x))
==> (eq? y (cdr x))
#t
==> (define x '(a b))
==> (define y '(b))
==> (eq? y (cdr x))
#f
==> (eq? 1000000000 1000000000)
#f (implementation dependent)
EQUAL?
;2つの引数のS表現が等しいかどうか調べるにはequal?
を用いる
==> (equal? 'a 'b)
#f
==> (equal? 'a 'a)
#t
==> (equal? 1 1)
#t
==> (equal? '(a) '(a))
#t
==> (define x '(a b))
==> (define y (cdr x))
==> (equal? y (cdr x))
#t
==> (define x '(a b))
==> (define y '(b))
==> (equal? y (cdr x))
#t
==> (equal? 1000000000 1000000000)
#t
=
;数値として等しいかどうか調べるには=を用いる
==> (= 'a 'b)
ERROR
==> (= 1 1)
#t
==> (= '(a) '(a))
ERROR
==> (= 1000000000 1000000000)
#t
他に，<,>,<=,>=などもある
null?
;'()(=空リスト)かどうか調べるにはnull?を用いる
==> (null? 'a)
#f
==> (null? '())
#t
==> (null? '(a))
#f
==> (null? 1000)
#f
list?
;リストかどうか調べるにはlist?を用いる
==> (list? 'a)
#f
==> (list? '())
#t
==> (list? '(a))
#t
==> (list? 1000)
#f
number?
;数値かどうか調べるにはnumber?を用いる
==> (number? 'a)
#f
==> (number? '())
#f
==> (number? '(a))
#f
==> (number? 1000)
#t
boolean?
;真偽値かどうか調べるにはboolean?を用いる
==> (boolean? 'a)
#f
==> (boolean? '())
#f
==> (boolean? '(a))
#f
==> (boolean? 1000)
#f
==> (boolean? #t)
#t
Last modified: Apr 28 23:13:48 JST 2006