* gnu/packages/version-control.scm (diffstat): New variable.

* guix/ftp-client.scm (%ftp-login): Add #\return before #\newline.
  Fixes access to some FTP servers, such as
  ftp://invisible-island.net ("ProFTPD 1.3.4a Server").

* gnu/system.scm (<operating-system>)[initrd]: Default to
  'qemu-initrd'.
  (<file-system>): New record type.
  (operating-system-root-file-system): New procedure.
  (operating-system-derivation): Take the device name for GRUB from
  'operating-system-root-file-system'.  Pass the
  'operating-system-initrd' procedure the list of boot file systems.
* gnu/system/linux-initrd.scm (file-system->spec): New procedure.
  (qemu-initrd): Add 'file-systems' parameter, and remove #:mounts
  parameter.
  [file-system-type-predicate]: New procedure.
  [linux-modules]: Use it.
  Adjust #:mounts argument in 'boot-system' call.
  (gnu-system-initrd): Remove.
* gnu/system/vm.scm (%linux-vm-file-systems): New variable.
  (expression->derivation-in-linux-vm): Adjust call to 'qemu-initrd'.
  (virtualized-operating-system): New procedure.
  (system-qemu-image/shared-store-script)[initrd]: Remove.  Use
  'virtualized-operating-system'.  Get the 'initrd' file from OS-DRV.
* guix/build/linux-initrd.scm (mount-qemu-smb-share, mount-qemu-9p):
  Remove.
  (MS_RDONLY, MS_BIND): New global variables.
  (bind-mount): Remove local 'MS_BIND' definition.
  (mount-root-file-system): New procedure, with code formerly in
  'boot-system'.
  (mount-file-system): New procedure.
  (boot-system): Add #:root-fs-type parameter.  Remove 'MS_RDONLY' local
  variable.  Use 'mount-root-file-system' and 'mount-file-system'.
* doc/guix.texi (Using the Configuration System): Add 'file-system'
  declaration.

* gnu/packages/maths.scm: Add copyright line missing from 3de01d3f.

* gnu/packages/maths.scm (petsc): Configure with superlu support.

* gnu/packages/maths.scm (superlu): New variable

* gnu/packages/qemu.scm (qemu-headless): Upgrade to 2.0.0.

* guix/download.scm (gnutls-derivation): Remove.
  (gnutls-package): New procedure.
  (url-fetch): Rewrite using 'gexp->derivation'.

* guix/gexp.scm (gexp->derivation, gexp->script): Use 'default-guile'
  instead of an explicit reference to 'guile-final'.
  (default-guile): New procedure.
* guix/monads.scm (run-with-store)[default-guile]: New procedure.
  Use it.

* guix/gexp.scm (lower-inputs, gexp-inputs, gexp->sexp,
  canonicalize-reference): Add 'origin?' case.
* guix/monads.scm (origin->derivation): New procedure.
* tests/gexp.scm ("one input origin"): New test.

* gnu/system.scm (<operating-system>)[groups]: Change default to just
  the 'root' group.
  [sudoers]: New field.
  (etc-directory): Add #:sudoers parameter.  Add 'sudoers' to the
  file union.
  (operating-system-etc-directory): Pass #:sudoers to 'etc-directory'.
  (%setuid-programs): Add 'sudo'.
  (%sudoers-specification): New variable.
* gnu/system/linux.scm (base-pam-services): Add 'sudo'.
* build-aux/hydra/demo-os.scm: Add 'groups' field; add 'guest' to the
  'wheel' group.

* gnu/packages/maths.scm (petsc): New variable.
  (petsc-complex): New variable.
* gnu/packages/patches/petsc-fix-threadcomm.patch: New patch.
* gnu-system.am (dist_patch_DATA): Add it.

* gnu/packages/games.scm (abbaye): New variable.

* gnu/packages/sdl.scm (sdl-image): Propagate jpeg, png, and tiff
  libraries.

* guix/gexp.scm (write-gexp): New procedure.
  <top level>: Add call to 'set-record-type-printer!'.

* gnu/packages/admin.scm (sudo): New variable.

* gnu/system.scm (<operating-system>)[pam-services, setuid-programs]:
  New fields.
  (etc-directory)[bashrc]: Prepend /run/setuid-programs to $PATH.
  (operating-system-etc-directory): Honor
  'operating-system-pam-services'.
  (%setuid-programs): New variable.
  (operating-system-boot-script): Add (guix build utils) to the set of
  imported modules.  Call 'activate-setuid-programs' in boot script.
* gnu/system/linux.scm (base-pam-services): New procedure.
* guix/build/activation.scm (%setuid-directory): New variable.
  (activate-setuid-programs): New procedure.
* build-aux/hydra/demo-os.scm: Add 'pam-services' field.

* guix/build/linux-initrd.scm (boot-system): Pass the 'suid' option to
  UNIONFS.

* gnu/services/dmd.scm (dmd-configuration-file): Remove 'etc'
  parameter.  Move /etc activation code to...
* guix/build/activation.scm: ... here; new file.
* gnu/system.scm (operating-system-boot-script): Augment script: add
  (guix build activation) to the load path; call 'activate-etc'.
* Makefile.am (MODULES): Add guix/build/activation.scm.

* gnu/packages/calcurse.scm: Define calcurse module correctly.

* gnu/packages/maths.scm (gmsh): Fix typo and space aftern
  end-of-sentence.

* gnu/packages/maths.scm (gmsh): New variable

* guix/derivations.scm (derivation->string): New procedure.
  (derivation-hash, derivation): Use it.
  Memoization here yields a 5% improvement on "guix build -e '(@ (gnu
  packages emacs) emacs)' -n --no-substitutes".

* gnu/packages/guile.scm (guile-ncurses)[arguments]: Pass
  "--with-ncursesw".

* guix/gnu-maintenance.scm (gnu-package?): Add 'mirror-type' procedure.
  Resort to 'official-gnu-packages' only when 'mirror-type' returns #f.

* guix/gexp.scm (gexp->sexp): Remove #:outputs parameter.  Adjust
  callers accordingly.

* gnu/packages/screen.scm (screen): Upgrade to 4.2.1.

* gnu/packages/guile.scm (mcron): Upgrade to 1.0.7.
  Use GUILE-2.0 instead of GUILE-1.8; add 'native-inputs' field.

* guix/monads.scm: Unexport 'lower-inputs' and 'derivation-expression'.
  (text-file*): Add comment about the switch to 'gexp->derivation'.
  (lower-inputs): Add comment about its doom.
  (derivation-expression): Likewise.
* guix/gexp.scm (lower-inputs*): Rename to...
  (lower-inputs): ... this.  Update callers.
* tests/monads.scm (derivation-expression): New procedure.
* doc/guix.texi (The Store Monad): Use 'gexp->derivation' instead of
  'derivation-expression'.  Remove documentation of
  'derivation-expression'.
* guix/ui.scm (read/eval): Use THE-ROOT-MODULE so that macros are
  properly expanded.
* tests/guix-build.sh: Use 'gexp->derivation' instead of
  'derivation-expression'.monads: Hide 'derivation-expression' and 'lower-inputs'.

* gnu/system/linux-initrd.scm (expression->initrd): Rename 'inputs'
  parameter to 'to-copy'.  Remove 'files-to-copy'.  Rewrite 'builder' as
  a gexp, and use 'gexp->derivation'.
  (qemu-initrd): Adjust accordingly.

* gnu/system.scm (union): Rewrite using 'gexp->derivation'.

* gnu/services/xorg.scm (xorg-start-command): Rewrite in terms of
  'gexp->script'.
  (xinitrc): Likewise.

* gnu/system/grub.scm (grub-configuration-file): Rewrite using
  'gexp->derivation'.
* gnu/system.scm (operating-system-derivation): Adjust accordingly.

* gnu/system.scm (file-union): Make 'name' the first parameter; remove
  'inputs' parameter.  Rewrite using 'gexp->derivation'.
  (etc-directory): Adjust accordingly.
  (operating-system-derivation): Ditto.

* 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".

* gnu/system/vm.scm (%imported-modules): Remove.
  (expression->derivation-in-linux-vm): Remove 'inputs' parameter.
  Rename 'imported-modules' to 'modules'.  Rewrite using gexps and
  'gexp->derivation'.
  (qemu-image): Add 'qemu' parameter.  Pass NAME to
  'expression->derivation-in-linux-vm'.  Rewrite using gexps.  Remove
  #:inputs argument to 'expression->derivation-in-linux-vm'.
  (operating-system-default-contents): Rewrite using gexps.
* gnu/system.scm (operating-system-profile-derivation): Rename to...
  (operating-system-profile): ... this.  Adjust callers.
  (operating-system-profile-directory): Remove.

* guix/store.scm (direct-store-path?): Return #f if PATH
  is (%store-prefix).
* tests/store.scm ("direct-store-path?"): Add test.

* gnu/system.scm (operating-system-boot-script): Use 'gexp->file'
  instead of 'text-file*'.
* gnu/system/vm.scm (expression->derivation-in-linux-vm): Likewise.
  (system-qemu-image/shared-store-script)[builder]: Turn into a gexp.
  Use 'gexp->derivation' instead of 'derivation-expression'.

* guix/gexp.scm: New file.
* tests/gexp.scm: New file.
* Makefile.am (MODULES): Add guix/gexp.scm.
  (SCM_TESTS): Add tests/gexp.scm.
* doc/guix.texi (Derivations): Add #:inputs in 'derivation' example.
  Mark 'build-expression->derivation' as deprecated, refer to
  "G-Expressions".  Remove paragraph about code strata.
  (G-Expressions): New node.