在Scheme中获取一行用户输入？

Question

我知道你可以使用(read)来获取用户输入的表达式,但是(read)只会得到第一个表达式,之后会对其进行评估.我想知道是否有任何方法可以读取整行用户输入,或许将所述行转换为列表？

(let ((input (read-user-line)))
   ;; user could type "cons 2 3" without quotes
   ;; input could contain '(cons 2 3)
   (apply (car input) (cdr input)))

谢谢!

Answer 1

If your Scheme is an R6RS implementation, you can use GET-LINE. If that same Scheme implements SRFI-13 as well, you can use STRING-TOKENIZE to turn it into a list.

One Scheme that qualifies is Ypsilon:

(import (srfi srfi-13))

(let ((input (get-line (current-input-port))))
  (for-each (lambda (x) (display x) (newline))
            (string-tokenize input)))

$ ypsilon try.scm
the quick brown fox jumps over the lazy dog.
the
quick
brown
fox
jumps
over
the
lazy
dog.

Otherwise you are on your own with whatever non-standard extensions your implementation provides.