services: 'mingetty-service' no longer takes monadic values.

* gnu/services/base.scm (mingetty-service): Change default value of
  #:motd from a monadic value to a <plain-file>.  Assume MOTD to be a
  file-like object.  Assume LOGIN-PROGRAM is a gexp or #f.
  (%base-services): Use 'plain-file' instead of 'text-file' for motd.
* gnu/system/linux.scm (unix-pam-service): Update docstring to mention
  that MOTD is a file-like object.
* doc/guix.texi (Base Services): Adjust 'mingetty-service' documentation
  accordingly.
* gnu/system/install.scm (installation-services): Adjust accordingly.
  (log-to-info): Use 'program-file' instead of 'gexp->script'.

doc/guix.texi

@@ -5764,7 +5764,7 @@ automatically.  @var{login-pause?} can be set to @code{#t} in conjunction with
 @var{auto-login}, in which case the user will have to press a key before the
 login shell is launched.
 
-When true, @var{login-program} is a gexp or a monadic gexp denoting the name
+When true, @var{login-program} is a gexp denoting the name
 of the log-in program (the default is the @code{login} program from the Shadow
 tool suite.)
 

gnu/services/base.scm

@@ -357,7 +357,7 @@ stopped before 'kill' is called."
 
 (define* (mingetty-service tty
                            #:key
-                           (motd (text-file "motd" "Welcome.\n"))
+                           (motd (plain-file "motd" "Welcome.\n"))
                            auto-login
                            login-program
                            login-pause?
@@ -374,19 +374,12 @@ automatically.  @var{login-pause?} can be set to @code{#t} in conjunction with
 @var{auto-login}, in which case the user will have to press a key before the
 login shell is launched.
 
-When true, @var{login-program} is a gexp or a monadic gexp denoting the name
+When true, @var{login-program} is a gexp denoting the name
 of the log-in program (the default is the @code{login} program from the Shadow
 tool suite.)
 
-@var{motd} is a monadic value containing a text file to use as
+@var{motd} is a file-like object to use as the ``message of the day''."
-the ``message of the day''."
+  (with-monad %store-monad
-  (mlet %store-monad ((motd motd)
-                      (login-program (cond ((gexp? login-program)
-                                            (return login-program))
-                                           ((not login-program)
-                                            (return #f))
-                                           (else
-                                            login-program))))
     (return
      (service
       (documentation (string-append "Run mingetty on " tty "."))
@@ -861,7 +854,7 @@ gexp, to open it, and evaluate @var{close} to close it."
 
 (define %base-services
   ;; Convenience variable holding the basic services.
-  (let ((motd (text-file "motd" "
+  (let ((motd (plain-file "motd" "
 This is the GNU operating system, welcome!\n\n")))
     (list (console-font-service "tty1")
           (console-font-service "tty2")

gnu/system/install.scm

@@ -102,7 +102,7 @@ under /root/.guix-profile where GUIX is installed."
 (define (log-to-info)
   "Return a script that spawns the Info reader on the right section of the
 manual."
-  (gexp->script "log-to-info"
+  (program-file "log-to-info"
                 #~(begin
                     ;; 'gunzip' is needed to decompress the doc.
                     (setenv "PATH" (string-append #$gzip "/bin"))
@@ -234,7 +234,7 @@ configuration template file in the installation system."
 
 (define (installation-services)
   "Return the list services for the installation image."
-  (let ((motd (text-file "motd" "
+  (let ((motd (plain-file "motd" "
 Welcome to the installation of the Guix System Distribution!
 
 There is NO WARRANTY, to the extent permitted by law.  In particular, you may

gnu/system/linux.scm

@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -136,7 +136,7 @@ dumped in /etc/pam.d/NAME, where NAME is the name of SERVICE."
     (lambda* (name #:key allow-empty-passwords? motd)
       "Return a standard Unix-style PAM service for NAME.  When
 ALLOW-EMPTY-PASSWORDS? is true, allow empty passwords.  When MOTD is true, it
-should be the name of a file used as the message-of-the-day."
+should be a file-like object used as the message-of-the-day."
       ;; See <http://www.linux-pam.org/Linux-PAM-html/sag-configuration-example.html>.
       (let ((name* name))
         (pam-service