store: Add substitute-related procedures.

* guix/store.scm (has-substitutes?, substitutable-paths,
  read-substitutable-path-list, substitutable-path-info): New
  procedures.
  (<substitutable>): New record type.
  (read-arg): Add `substitutable-path-info'.  Change `hash' pattern
  variable to `base16' literal.
* tests/store.scm ("no substitutes"): New test.

tests: Fix thinko in `derivation' test.

* tests/derivations.scm ("derivation with local file as input"): Return
  a Boolean instead of a bytevector.  Don't attempt to compare the
  content of the result with that of the input.

Augment `.dir-locals.el'.

* .dir-locals.el: Add more Scheme settings.
* guix-build.in, tests/base32.scm, tests/build-utils.scm,
  tests/builders.scm, tests/derivations.scm, tests/packages.scm,
  tests/snix.scm, tests/store.scm, tests/union.scm, tests/utils.scm:
  Remove redundant Emacs local variable settings.

guix-package: Report `--search' matches in recutils format.

* guix/ui.scm (fill-paragraph, string->recutils, package->recutils): New
  procedures.
* guix-package.in (guix-package)[process-query]: Use `package->recutils'
  to display package meta-data.
* tests/guix-package.sh: Adjust test.
* tests/ui.scm: New file.
* Makefile.am (TESTS): Add it.
* doc/guix.texi (Invoking guix-package): Adjust `--search'
  documentation, and give an example.

guix-package: Gracefully report non-existing outputs.

* guix-package.in (guix-package)[find-package](ensure-output): New
  procedure. Use it to validate SUB-DRV.

store: Remove the `fixed?' parameter from `add-to-store'.

* guix/store.scm (add-to-store): Remove the `fixed?' parameter from the
  public interface.
* gnu/packages/bootstrap.scm, guix-download.in, guix/derivations.scm,
  guix/packages.scm, tests/derivations.scm: Update all callers
  accordingly.

guix-package: Add '--search'.

* guix-package.in (find-packages-by-description): New procedure.
  (show-help, %options): Add '--search'.
  (guix-package)[process-query]: Add support for '--search'.
* doc/guix.texi (Invoking guix-package): Document it.
* tests/guix-package.sh: Add tests.

guix-package: Always use the next number for new generations.

Suggested by Andreas Enge <andreas@enge.fr> at
<http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00325.html>.

* guix-package.in (latest-profile-number): Remove.
  (switch-symlinks): New procedure.
  (roll-back)[switch-link]: Use it.
  (guix-package)[process-actions]: Always choose NUMBER + 1 for the new
  profile.  Use `switch-symlinks' instead of `symlink'.  Remove code to
  delete PROFILE when it exists since `switch-symlinks' has the same
  effect.
* tests/guix-package.sh: Adjust existing `--roll-back' tests.
* doc/guix.texi (Invoking guix-package): Document this `--roll-back'
  behavior.

guix-package: When rolling back to nothingness, point to the empty profile.

Suggested by Andreas Enge <andreas@enge.fr> at
<http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00316.html>.

* guix-package.in (roll-back): Check whether PROFILE is valid using
  `file-exists?'.  When NUMBER is zero, just emit a notice.  When
  PREVIOUS-NUMBER is zero and PREVIOUS-PROFILE does not exist, build the
  empty profile, and link to it.
* tests/guix-package.sh: Add tests.
* doc/guix.texi (Invoking guix-package): Document the new behavior.

packages: Mark the `inputs' field of <package> as thunked.

* guix/packages.scm (<package>)[inputs]: Mark as thunked.
  (package-derivation)[expand-input]: Remove case where the input is a
  procedure.
* tests/packages.scm ("trivial with system-dependent input"): Remove
  `lambda', and use (%current-system).
* gnu/packages/bootstrap.scm (package-from-tarball): Likewise for `inputs'.
  (%bootstrap-glibc, %bootstrap-gcc): Likewise.
* gnu/packages/scheme.scm (mit-scheme): Likewise.

guix-package: Error out when passed a non-option argument.

* guix-package.in (guix-package)[parse-options]: Call `leave' when
  passed a non-option argument.
  Reported by Andreas Enge <andreas@enge.fr>.
* tests/guix-package.sh: Add test.

define-record-type*: Add the `thunked' field definition keyword.

* guix/utils.scm (define-record-type*)[make-syntactic-constructor]: Add
  a `thunked' parameter.
  (thunked-field?, field-bindings): New procedures.  Use the latter when
  generating `letrec*' bindings.
  [thunked-field?, thunked-field-accessor-name, field-spec->srfi-9,
  thunked-field-accessor-name]: New procedures.
  Use them when generating the `define-record-type' form, and to
  generated thunk field accessors, along call to
  `make-syntactic-constructor' with the new argument.
* tests/utils.scm ("define-record-type* & thunked",
  "define-record-type* & thunked & default",
  "define-record-type* & thunked & inherited"): New tests.

guix-package: Fix `--roll-back' when `--profile' is not passed.

* guix-package.in (roll-back): Fix file name of PREVIOUS-PROFILE, which
  could end up containing the dirname twice.
  Reported by Nikita and Andreas.
* tests/guix-package.sh: Add test.

guix-build: Allow version-qualified package names.

* guix-build.in (guix-build)[find-package]: New procedure.
  Use it instead of using `find-packages-by-name' directly.
  Suggested by Andreas Enge <andreas@enge.fr>.
* tests/guix-build.sh: Add tests.
* doc/guix.texi (Invoking guix-build): Add `coreutils-8.20' as an
  example.  Fix guile-1.8 example.

packages: Have `package-derivation' return a <derivation> as a second value.

* guix/packages.scm (cache): Change the `drv' argument to `thunk'.
  Memoize all the return values of THUNK.
  (cached-derivation): Remove.
  (cached): New macro.
  (package-derivation): Use `cached' instead of `(or (cached-derivation) …)'.
* doc/guix.texi (Defining Packages): Update accordingly.

distro: Rename (distro) to (gnu packages).

* distro.scm: Rename to...
* gnu/packages.scm: ... this.  Update all users accordingly.
* Makefile.am (MODULES): Adjust accordingly.
* po/POTFILES.in: Likewise.

distro: Change the module name space to (gnu ...).

* distro: Rename to...
* gnu: ... this.  Update module names accordingly.
* Makefile.am: Adjust accordingly.
* po/POTFILES.in: Likewise.
* distro.scm: Search for files under /gnu/packages instead of
  /distro/packages.
* gnu/packages/base.scm (ld-wrapper-boot3): Likewise.

guix-package: Allow `--roll-back' to skip missing generations.

* guix-package.in (profile-numbers): New procedure.
  (latest-profile-number): Use it.
  (previous-profile-number): New procedure.
  (roll-back): Use it lieu of `1-'.  Check whether PREVIOUS-NUMBER is
  zero, and raise an error when it is.
* tests/guix-package.sh: Test whether we can roll back over a "hole".

guix-package: Add `--roll-back'.

Based on a patch by Nikita Karetnikov <nikita@karetnikov.org>.

* guix-package.in (profile-regexp): New procedure.
  (latest-profile-number): Remove `%profile-rx', and use
  `profile-regexp' instead.
  (profile-number, roll-back): New procedure.
  (show-help): Add `--roll-back'.
  (%options): Likewise.
  (guix-package)[process-actions]: First check whether `roll-back?' is
  among OPTS, and call `roll-back' if it is, followed by a recursive
  call to `process-actions'.  Emit the "nothing to be done" message only
  when INSTALL or REMOVE is non-empty.
* tests/guix-package.sh (readlink_base): New function.
  Add tests for `--roll-back'.
* doc/guix.texi (Invoking guix-package): Document `--roll-back'.

guix-package: Create or diagnose missing profile directory.

Reported by Andreas Enge.

* guix-package.in (%profile-directory): Honor $NIX_STATE_DIR.
  (guix-package)[ensure-default-profile]: Use it.
  [process-actions]: Call it when the `profile' option is
  %CURRENT-PROFILE.
* tests/guix-package.sh: Add installation test with $HOME set, using the
  default profile.