(defun shasums (dir)
  (with-stream (chks (open-file `@dir/CHECKSUMS` "w"))
    (put-line "File SHA256 sums:\n" chks)
    (each ((name (glob `@dir/*`)))
      (when (nequal (base-name name) "CHECKSUMS")
        (with-stream (s256 (open-file name "r"))
          (format chks "~x  ~a\n"
                  (uint-buf (sha256-stream s256))) (base-name name))))))