Re: A good idiom for EOF when READing files?

but then I noticed that if the file had the symbol EOF in it, then the
READing would be short-circuited.  In particular, if a file "foo" has
the contents:

 [...]

After a bit of thought, it occurred to me that I could use a gensym as
the EOF indicator, as:

 
Yep, that's one common way of dealing with it.  Personally, I use:
 
  (defvar *eof* (gensym))
 
So at least this way, I only have one gensym per image used on eof
values.  Plus I find it a tiny bit clearer.
 

(defun list-expressions (file)
  (with-open-file (instream file :direction :input)
    (let ((eof (gensym)))             ;generate a safe EOF marker
      (do ((sexp (read instream nil eof) (read instream nil eof))
         (output nil (push sexp output)))
        ((eql sexp eof) (nreverse output))))))

 
  (defun list-expressions (file)
    (with-open-file (instream file :direction :input)
      (loop for sexp = (read instream nil *eof*)
            until (eql sexp *eof*)
            collect sexp)))
 
Oh yeah, unlike Graham, I like LOOP.  Go ahead and use DO until you
feel comfortable with it, and with Lisp in general, then give LOOP a
spin.

Gauche Scheme

(use srfi-42 :only (list-ec))

(define (list-expressions file)
  (call-with-input-file file
    (lambda (inport) (list-ec (:port x inport) x))))

Another way:

(define (list-expressions file)
  (call-with-input-file file port->sexp-list))