;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2016 John Darrington <jmd@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gnu services kerberos)
  #:use-module (gnu services)
  #:use-module (gnu services configuration)
  #:use-module (gnu system pam)
  #:use-module (guix gexp)
  #:use-module (guix records)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:use-module (ice-9 match)
  #:export (pam-krb5-configuration
            pam-krb5-configuration?
            pam-krb5-service-type

            krb5-realm
            krb5-realm?

            krb5-configuration
            krb5-configuration?
            krb5-service-type))



;; TODO Use %unset-value and the define-maybe infrastructure.
(define unset-field (list 'unset-field))

(define (predicate/unset pred)
  (lambda (x) (or (eq? x unset-field) (pred x))))

(define string/unset? (predicate/unset string?))
(define boolean/unset? (predicate/unset boolean?))
(define integer/unset? (predicate/unset integer?))

(def