How to test for end of file?

[back0003 <back0003@gold.tc.umn.edu>]

Any clues are welcome.

(define (witless-grep)
        (let ((temp-line (read-line my-file)))
          (if (= temp-line end-of-file)          ;; How to test for EOF?
              #t
          (if (string-match my-regular-expression temp-line)
                (begin
                  (write-string temp-line)
                  (newline)
                  (witless-grep))
                (witless-grep)))))

Jan Erik Backlund
back0003@gold.tc.umn.edu