Input / Output

• Write file

(let ((stream (open "/some/file/name.txt" :direction :output)))
  (format stream "hello world~%")
    (close stream))

• or using a macro

• :if-exists :supersede will override an existing file

(with-open-file (out filename
                 :direction :output
                 :if-exists :supersede)
   (with-standard-io-syntax
     (print *content* out))))

• Read file

(let ((in (open "/some/file/name.txt" :if-does-not-exist nil)))
  (when in
    (loop for line = (read-line in nil)
             while line do (format t "~a~%" line))
                 (close in)))

• or using a macro

(with-open-file (in filename)
  (with-standard-io-syntax
    (setf *content* (read in)))))

• Ask user for Input

(defun prompt-read (prompt)
  (format *query-io* "~a: " prompt)
  (force-output *query-io*)
  (read-line *query-io*))