package - Common Lisp 包中的外部符号与内部符号

Question

它们在 Common Lisp 包的上下文中有什么区别？我正在阅读 SLIME 文档，一些命令广泛提到了这一点。

Answer 1

语法是什么？您导出的符号是外部的。

(in-package :cl-user)
(defpackage str
  (:use :cl)
  (:export
   :trim-left
   ))

(in-package :str)

;; exported: can be accessed with `str:trim-left`.
(defun trim-left (s)
  "Remove whitespaces at the beginning of s. "
  (string-left-trim *whitespaces* s))

;; forgot to export: can still access it with `str::trim-right`.
(defun trim-right (s)
  "Remove whitespaces at the end of s."
  (string-right-trim *whitespaces* s))