Beginner - Function Critique

See below. These functions have been created a thousand times and are trivial, but I wrote these instances myself and am a pretty proud beginner. What do you think?

A week ago recursion was still pretty hazy, but a after reading "Common Lisp, An Interactive Approach" the progress has been steady. What a great book.

;;;;;;;;;;;;;;;;

(defpackage :string-utils
  (:use :common-lisp))

(in-package :string-utils)

(defun line-split (s d)
  "Return a list of substrings in string S when delimited by delimiter D."
  (check-type s string)
  (check-type d character)
  (if (= (length s) 0) '()
      (cons (getf (line-split1 s d) :string)
            (line-split (getf (line-split1 s d) :remainder) d))))

(defun line-split1 (s d)
"Helper function for LINE-SPLIT. Return a list with elements of supplied string S up to the first instance of delimiter D as :STRING and the remaining string after the delimiter as :REMAINDER."
(if (position d s) (list :string (subseq s 0 (position d s))
:remainder (subseq s (1+ (position d s))))
(list :string s :remainder "")))

(defun read-file (filename delimiter)
"Return a list of lists containing strings in pathname FILENAME delimited by character DELIMITER."
(let ((output '()))
(with-open-file (in filename)
(do ((line (read-line in nil) (read-line in nil)))
((null line))
(push (line-split line delimiter) output))
(nreverse output))))

(defmacro join-strings (&rest strings)
  "Return the result of concatenating the supplied strings."
  `(concatenate 'string ,@strings))

(defun rjust (s w)
  "Right justify string S by W spaces."
  (rjust1 s (- w (length s))))

(defun rjust1 (s w)
  "Helper function for RJUST."
  (if (<= w 0) s
      (join-strings (rjust1 s (1- w)) " ")))

(defun ljust (s w)
  "Left justify string S by W spaces."
  (ljust1 s (- w (length s))))

(defun zfill (s w)
  "Left justify string S by W 0 characters."
  (ljust1 s (- w (length s)) "0"))

(defun ljust1 (s w &optional (c " "))
  "Helper function for LJUST."
  (if (<= w 0) s
      (join-strings c (ljust1 s (1- w) c))))
.