CODEWITHSUNDEEP
common-lisp
Tino
Tino

Reputation: 229

Common Lisp, read from file recursively

How can i read from file recursively, in Common Lisp. I find a lot of examples the are iterative, but i need recursive method. Currently i'm training something like this:

(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))

Upvotes: 1

Views: 719

Answers (1)

Frank Zalkow
Frank Zalkow

Reputation: 3930

First, in CL it is good style not having opening or closing paranthesis only on a line.

Here is an approach to read-char recursively until EOF.

(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))))

You can use it like this:

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

Upvotes: 3

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