gnu: Allow a plain list of packages in 'operating-system'.

* gnu/system.scm (union): Allow (PACKAGE OUTPUT), (PACKAGE), and
  PACKAGE.
  (<operating-system>)[packages]: Make the default a list of package?
  objects.
* gnu/system/vm.scm (%demo-operating-system): Likewise.  Add a few
  packages.

gnu/system.scm

@@ -78,12 +78,14 @@ (define-record-type* <operating-system> operating-system
                           (members '("guest"))))))
 
   (packages operating-system-packages             ; list of (PACKAGE OUTPUT...)
-            (default `(("coreutils" ,coreutils)
-                       ("grep" ,grep)
-                       ("guile" ,guile)
-                       ("bash" ,bash)
-                       ("dmd" ,(@ (gnu packages dmd) dmd))
-                       ("guix" ,guix))))
+            (default (list coreutils              ; or just PACKAGE
+                           grep
+                           sed
+                           findutils
+                           guile
+                           bash
+                           (@ (gnu packages dmd) dmd)
+                           guix)))
 
   (timezone operating-system-timezone)            ; string
   (locale   operating-system-locale)              ; string
@@ -134,11 +136,11 @@ (define builder
   (mlet %store-monad
       ((inputs (sequence %store-monad
                          (map (match-lambda
-                               ((name (? package? p))
+                               ((or ((? package? p)) (? package? p))
                                 (mlet %store-monad
                                     ((drv (package->derivation p system)))
                                   (return `(,name ,drv))))
-                               ((name (? package? p) output)
+                               (((? package? p) output)
                                 (mlet %store-monad
                                     ((drv (package->derivation p system)))
                                   (return `(,name ,drv ,output))))

gnu/system/vm.scm

@@ -25,9 +25,11 @@ (define-module (gnu system vm)
   #:use-module ((gnu packages base)
                 #:select (%final-inputs
                           guile-final gcc-final glibc-final
+                          ld-wrapper binutils-final
                           coreutils findutils grep sed))
   #:use-module (gnu packages guile)
   #:use-module (gnu packages bash)
+  #:use-module (gnu packages less)
   #:use-module (gnu packages qemu)
   #:use-module (gnu packages parted)
   #:use-module (gnu packages zile)
@@ -416,20 +418,23 @@ (define %demo-operating-system
                  (uid 1000) (gid 100)
                  (comment "Guest of GNU")
                  (home-directory "/home/guest"))))
-   (packages `(("coreutils" ,coreutils)
-               ("bash" ,bash)
-               ("guile" ,guile-2.0)
-               ("dmd" ,dmd)
-               ("gcc" ,gcc-final)
-               ("libc" ,glibc-final)
-               ("inetutils" ,inetutils)
-               ("findutils" ,findutils)
-               ("grep" ,grep)
-               ("sed" ,sed)
-               ("procps" ,procps)
-               ("psmisc" ,psmisc)
-               ("zile" ,zile)
-               ("guix" ,guix)))))
+   (packages (list coreutils
+                   bash
+                   guile-2.0
+                   dmd
+                   gcc-final
+                   ld-wrapper                    ; must come before BINUTILS
+                   binutils-final
+                   glibc-final
+                   inetutils
+                   findutils
+                   grep
+                   sed
+                   procps
+                   psmisc
+                   zile
+                   less
+                   guix))))
 
 (define* (system-qemu-image #:optional (os %demo-operating-system))
   "Return the derivation of a QEMU image of the GNU system."