(defun count-spaces-in-lines (pathname)
  (with-open-file (stream pathname)
    (loop :for line := (read-line stream nil)
          :while line
          :collect (count-if (lambda (ch) (find ch #(#\space #\tab))) line))))
(count-spaces-in-lines "/etc/passwd")
--> (0 2 1 13 12 2 0 9 2 0 1 1 1 4 2 1 1 1 2 2 2 3 1 1 2 1 0 0 2 3 2 1 1 1 2 2 1 2 1 1 1 2 1 0 0 1 0 0 0 1 0 1 1 1 2 2 0 1 2 0 2 1 3 1 1 1 3 2 3 2 2 0 1 1 2 3 5 4 5 2 3 2 3 0 0 0 1 1 2 1 2 2 1 3 3 1 1 3 0 0 1 1 2 3 1 1 2 0)