摘要：(let ((var expr) ...) body1 body2 ...)(letrec ((var expr) ...) body1 body2 ...)Like let, the letrec syntactic form includes a set of variable-value pairs, along with a sequence of expressions referred to as the body of the letrec.Unlike let, the variables var ... are visible not only within the body 阅读全文

摘要：1 > (cons 1 3) 2 (1 . 3) 3 > (car (cons 1 3)) 4 1 5 > (pair? (cons 1 3)) 6 #t 7 > (cdr (cons 1 3)) 8 3 9 > (list? (cons 1 3))10 #f11 > (pair? '())12 #f13 > (list? '())14 #t 阅读全文