scheme - 列出方案中所有用户定义的变量

Question

在 python 中我可以使用dir()而在球拍（5.2）中我可以

 (require xrepl)
 ,apropos

获取所有已定义变量的列表。在所有方案中都有什么可移植的方法来做同样的事情？完成后，如何过滤掉所有系统和模块变量？变量的完整列表在球拍中相当令人生畏。

Answer 1

要获取 Racket 中特定模块导出的名称，请使用module->exports。对于其他实现，您需要在文档中查找。

> (module->exports 'racket/list)
'((0
   (add-between ()) (append* ())    (append-map ())
   (argmax ())      (argmin ())     (cons? ()) (count ())
   (drop ())        (drop-right ()) (eighth ()) (empty ())
   (empty? ())      (fifth ())      (filter-map ())
   (filter-not ())  (first ())      (flatten ())
   (fourth ())      (last ())       (last-pair ())
   (make-list ())   (ninth ())      (partition ())
   (range ())       (rest ())       (second ())
   (seventh ())     (shuffle ())    (sixth ())
   (split-at ())    (split-at-right ()) (take ())
   (take-right ())  (tenth ()) (third ())))
'((0 (remove-duplicates ())))

Answer 2

好吧，这里是如何在guile (v. >= 2.0) 中做到这一点：

scheme@(guile-user)> ,binding
%module-public-interface #<variable 9e55e98 value: #<interface (guile-user) 9df6678>>

scheme@(guile-user)> (define foo 'bar)

scheme@(guile-user)> ,binding
foo                     #<variable a06fe28 value: bar>
%module-public-interface #<variable 9e55e98 value: #<interface (guile-user) 9df6678>>

您可以更改上下文以获取某些模块导出的绑定：

scheme@(guile-user)> (use-modules (srfi srfi-1))
scheme@(guile-user)> ,module (srfi srfi-1)
scheme@(srfi srfi-1)> ,binding
reduce-right            #<variable 9ead2d0 value: #<procedure reduce-right (f ridentity lst)>>
delete                  #<variable 9eb7aa8 value: #<procedure delete (_ _ #:optional _)>>
lset-xor!               #<variable 9eb7c90 value: #<procedure lset-xor! (= . rest)>>
take!                   #<variable 9ead640 value: #<procedure take! (lst i)>>
...