Common lisp 公共Lisp，从文件中递归读取

如何使用公共Lisp递归读取文件。我发现很多例子都是迭代的，但我需要递归的方法。 目前我正在进行如下培训：

(defun read-r()
  (let ((in (open 'input.txt)))
    (read-arrayR in)
  )
)

(defun read-arrayR(in)
    ( 
      (lambda()
        (setq num (char (read in nil)
                  (read in nil))
        )
      )
    )
    (if (null num)
      (
        (lambda()
          (colect num)
          (read-arrayR in)
        ) 
      )
    )
)

(setq arr (read-r))

(with-open-file (file-stream "input.txt")
  (with-output-to-string (string-stream)
    (read-recursive file-stream string-stream)
    string-stream))

---

首先，在CL中，它是一种好的风格，不只是在一行上有开始或结束的偏执

下面是一种递归读取字符直到EOF的方法

(defun read-recursive (stream-in stream-out)
  (let ((char (read-char stream-in nil)))
    (unless (null char)
      (format stream-out "~c" char)
      (read-recursive stream-in stream-out))))

您可以这样使用它：

(defun read-r()
  (let ((in (open 'input.txt)))
    (read-arrayR in)
  )
)

(defun read-arrayR(in)
    ( 
      (lambda()
        (setq num (char (read in nil)
                  (read in nil))
        )
      )
    )
    (if (null num)
      (
        (lambda()
          (colect num)
          (read-arrayR in)
        ) 
      )
    )
)

(setq arr (read-r))

(with-open-file (file-stream "input.txt")
  (with-output-to-string (string-stream)
    (read-recursive file-stream string-stream)
    string-stream))