LISP 6.1 变量的基础

CL-USER> (defun foo(x)   (format t "Parameter:~a~%" x)   (let ((x 2))     (format t "Out LET: ~a~%" x)     (let ((x 3))       (format t "Inner LET: ~a~%" x))     (format t "Out LET: ~a~%" x))   (format t "Parameter:~a~%" x))       FOOCL-USER> (foo 1)Parameter:1Out LET: 2Inner LET: 3Out LET: 2Parameter:1NIL

let的作用域范围被限定在引入该变量的形式之内