services: Rewrite using gexps.

* gnu/services.scm (<service>)[inputs]: Remove.
* gnu/system.scm (links): Remove.
  (etc-directory): Add PASSWD and SHADOW to #:inputs.
  (operating-system-boot-script): Pass ETC to 'dmd-configuration-file'.
  (operating-system-derivation): Remove EXTRAS from the union.
* gnu/system/linux.scm (pam-service->configuration): Rewrite in terms of
  'gexp->derivation'.  Compute the contents on the build side.  Expect
  'arguments' to contain a list of gexps.
  (pam-services->directory): Rewrite in terms of 'gexp->derivation'.
  (unix-pam-service): Change 'arguments' to a list of one gexp.
* gnu/system/shadow.scm (<user-account>)[inputs]: Remove.
  [shell]: Change default value to a gexp.
  (passwd-file): Rewrite in terms of 'gexp->derivation'.  Compute
  contents on the build side.
* gnu/services/base.scm (host-name-service, mingetty-service,
  nscd-service, syslog-service, guix-service): Change 'start' and 'stop'
  to gexps; remove 'inputs' field.
  (guix-build-accounts): Change 'shell' field to a gexp.
* gnu/services/networking.scm (static-networking-service): Change
  'start' and 'stop' to gexps; remove 'inputs' field.
* gnu/services/xorg.scm (slim-service): Likewise.
* gnu/services/dmd.scm (dmd-configuration-file): Expect ETC to be a
  derivation.  Change 'config' to a gexp.  Use 'gexp->file' instead of
  'text-file'.
* doc/guix.texi (Defining Services): Update nscd example with gexps, and
  without 'inputs'.  Add xref to "G-Expressions".

2 files changed, 57 insertions, 65 deletions

diff --git a/gnu/system/linux.scm b/gnu/system/linux.scm
index 65868ce9bf..efe27c55c3 100644
--- a/gnu/system/linux.scm
+++ b/gnu/system/linux.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -21,6 +21,7 @@
   #:use-module (guix records)
   #:use-module (guix derivations)
   #:use-module (guix monads)
+  #:use-module (guix gexp)
   #:use-module (ice-9 match)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-26)
@@ -58,58 +59,56 @@
 (define-record-type* <pam-entry> pam-entry
   make-pam-entry
   pam-entry?
-  (control    pam-entry-control)                  ; string
-  (module     pam-entry-module)                   ; file name
-  (arguments  pam-entry-arguments                 ; list of strings
+  (control    pam-entry-control)         ; string
+  (module     pam-entry-module)          ; file name
+  (arguments  pam-entry-arguments        ; list of string-valued g-expressions
               (default '())))
 
 (define (pam-service->configuration service)
-  "Return the configuration string for SERVICE, to be dumped in
-/etc/pam.d/NAME, where NAME is the name of SERVICE."
-  (define (entry->string type entry)
+  "Return the derivation building the configuration file for SERVICE, to be
+dumped in /etc/pam.d/NAME, where NAME is the name of SERVICE."
+  (define (entry->gexp type entry)
     (match entry
       (($ <pam-entry> control module (arguments ...))
-       (string-append type "  "
-                      control " " module " "
-                      (string-join arguments)
-                      "\n"))))
+       #~(format #t "~a ~a ~a ~a~%"
+                 #$type #$control #$module
+                 (string-join (list #$@arguments))))))
 
   (match service
     (($ <pam-service> name account auth password session)
-     (string-concatenate
-      (append (map (cut entry->string "account" <>) account)
-              (map (cut entry->string "auth" <>) auth)
-              (map (cut entry->string "password" <>) password)
-              (map (cut entry->string "session" <>) session))))))
+     (define builder
+       #~(begin
+           (with-output-to-file #$output
+             (lambda ()
+               #$@(append (map (cut entry->gexp "account" <>) account)
+                          (map (cut entry->gexp "auth" <>) auth)
+                          (map (cut entry->gexp "password" <>) password)
+                          (map (cut entry->gexp "session" <>) session))
+               #t))))
+
+     (gexp->derivation name builder))))
 
 (define (pam-services->directory services)
   "Return the derivation to build the configuration directory to be used as
 /etc/pam.d for SERVICES."
   (mlet %store-monad
       ((names -> (map pam-service-name services))
-       (files (mapm %store-monad
-                    (match-lambda
-                     ((and service ($ <pam-service> name))
-                      (let ((config (pam-service->configuration service)))
-                        (text-file (string-append name ".pam") config))))
-
-                    ;; XXX: Eventually, SERVICES may be a list of monadic
-                    ;; values instead of plain values.
-                    (map return services))))
+       (files (sequence %store-monad
+                        (map pam-service->configuration
+                             ;; XXX: Eventually, SERVICES may be a list of
+                             ;; monadic values instead of plain values.
+                             services))))
     (define builder
-      '(begin
-         (use-modules (ice-9 match))
+      #~(begin
+          (use-modules (ice-9 match))
 
-         (let ((out (assoc-ref %outputs "out")))
-           (mkdir out)
-           (for-each (match-lambda
-                      ((name . file)
-                       (symlink file (string-append out "/" name))))
-                     %build-inputs)
-           #t)))
+          (mkdir #$output)
+          (for-each (match-lambda
+                     ((name file)
+                      (symlink file (string-append #$output "/" name))))
+                    '#$(zip names files))))
 
-    (derivation-expression "pam.d" builder
-                           #:inputs (zip names files))))
+    (gexp->derivation "pam.d" builder)))
 
 (define %pam-other-services
   ;; The "other" PAM configuration, which denies everything (see
@@ -149,7 +148,8 @@ should be the name of a file used as the message-of-the-day."
                             (pam-entry
                              (control "optional")
                              (module "pam_motd.so")
-                             (arguments (list (string-append "motd=" motd)))))
+                             (arguments
+                              (list #~(string-append "motd=" #$motd)))))
                       (list unix))))))))
 
 ;;; linux.scm ends here
diff --git a/gnu/system/shadow.scm b/gnu/system/shadow.scm
index 2a85a20ebb..52242ee4e0 100644
--- a/gnu/system/shadow.scm
+++ b/gnu/system/shadow.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -20,6 +20,7 @@
   #:use-module (guix store)
   #:use-module (guix records)
   #:use-module (guix packages)
+  #:use-module (guix gexp)
   #:use-module (guix monads)
   #:use-module ((gnu packages admin)
                 #:select (shadow))
@@ -35,7 +36,6 @@
             user-account-comment
             user-account-home-directory
             user-account-shell
-            user-account-inputs
 
             user-group
             user-group?
@@ -63,9 +63,8 @@
   (gid            user-account-gid)
   (comment        user-account-comment (default ""))
   (home-directory user-account-home-directory)
-  (shell          user-account-shell              ; monadic value
-                  (default (package-file bash "bin/bash")))
-  (inputs         user-account-inputs (default `(("bash" ,bash)))))
+  (shell          user-account-shell              ; gexp
+                  (default #~(string-append #$bash "/bin/bash"))))
 
 (define-record-type* <user-group>
   user-group make-user-group
@@ -97,29 +96,22 @@
 SHADOW? is true, then it is a /etc/shadow file, otherwise it is a /etc/passwd
 file."
   ;; XXX: The resulting file is world-readable, so beware when SHADOW? is #t!
-  (define (contents)
-    (with-monad %store-monad
-      (let loop ((accounts accounts)
-                 (result   '()))
-        (match accounts
-          ((($ <user-account> name pass uid gid comment home-dir mshell)
-            rest ...)
-           (mlet %store-monad ((shell mshell))
-             (loop rest
-                   (cons (if shadow?
-                             (string-append name
-                                            ":"    ; XXX: use (crypt PASS …)?
-                                            ":::::::")
-                             (string-append name
-                                            ":" "x"
-                                            ":" (number->string uid)
-                                            ":" (number->string gid)
-                                            ":" comment ":" home-dir ":" shell))
-                         result))))
-          (()
-           (return (string-join (reverse result) "\n" 'suffix)))))))
+  (define account-exp
+    (match-lambda
+     (($ <user-account> name pass uid gid comment home-dir shell)
+      (if shadow?                                 ; XXX: use (crypt PASS …)?
+          #~(format #t "~a::::::::~%" #$name)
+          #~(format #t "~a:x:~a:~a:~a:~a:~a~%"
+                    #$name #$(number->string uid) #$(number->string gid)
+                    #$comment #$home-dir #$shell)))))
 
-  (mlet %store-monad ((contents (contents)))
-    (text-file (if shadow? "shadow" "passwd") contents)))
+  (define builder
+    #~(begin
+        (with-output-to-file #$output
+          (lambda ()
+            #$@(map account-exp accounts)
+            #t))))
+
+  (gexp->derivation (if shadow? "shadow" "passwd") builder))
 
 ;;; shadow.scm ends here