Merge branch 'master' into core-updates

Add (guix scripts).

* guix/ui.scm: Add missing copyright lines.
  (args-fold*, environment-build-options, %default-argument-handler,
  parse-command-line): Move to ...
* guix/scripts.scm: ...here.  New file.
* guix/scripts/archive.scm: Use it.
* guix/scripts/build.scm: Likewise.
* guix/scripts/download.scm: Likewise.
* guix/scripts/edit.scm: Likewise.
* guix/scripts/environment.scm: Likewise.
* guix/scripts/gc.scm: Likewise.
* guix/scripts/graph.scm: Likewise.
* guix/scripts/hash.scm: Likewise.
* guix/scripts/import/cpan.scm: Likewise.
* guix/scripts/import/cran.scm: Likewise.
* guix/scripts/import/elpa.scm: Likewise.
* guix/scripts/import/gem.scm: Likewise.
* guix/scripts/import/gnu.scm: Likewise.
* guix/scripts/import/hackage.scm: Likewise.
* guix/scripts/import/nix.scm: Likewise.
* guix/scripts/import/pypi.scm: Likewise.
* guix/scripts/lint.scm: Likewise.
* guix/scripts/package.scm: Likewise.
* guix/scripts/publish.scm: Likewise.
* guix/scripts/pull.scm: Likewise.
* guix/scripts/refresh.scm: Likewise.
* guix/scripts/size.scm: Likewise.
* guix/scripts/system.scm: Likewise.
* tests/ui.scm (with-environment-variable, "parse-command-line",
  "parse-command-line and --no options"): Move to ...
* tests/scripts.scm: ...here.  New file.
* Makefile.am (MODULES): Add guix/scripts.scm.
  (SCM_TESTS): Add tests/scripts.scm.
* po/guix/POTFILES.in: Add guix/scripts.scm.

scripts: environment: Return the exit status of the command.

* guix/scripts/environment.scm (guix-environment): Return the exit
  status of the command.

environment: Define 'GUIX_ENVIRONMENT'.

* guix/scripts/environment.scm (create-environment): Define 'GUIX_ENVIRONMENT'.
* doc/guix.texi (Invoking guix environment): Document it.
* gnu/system/shadow.scm (default-skeletons): Adjust 'PS1' depending on whether
  'GUIX_ENVIRONMENT' is defined.

environment: Improve error reporting for '-l'.

This fixes two problems:

  1. Load errors would print an ugly backtrace.
  2. When FILE was an absolute name, 'load' was passed an incorrect file
     name.

* guix/scripts/environment.scm (options/resolve-packages): Use 'load*' instead
  of 'load'.

environment: For --ad-hoc, allow users to specify an output.

* guix/scripts/environment.scm (package+propagated-inputs): Add 'output'
  parameter.  Use it in return value.
  (options/resolve-packages): Use 'append-map' instead of 'map'.  For 'load'
  and 'expression', return all the outputs of the resulting package.  For
  'package', use 'specification->package+output' instead of
  'specification->package'.
  (guix-environment): Adjust uses of PACKAGES accordingly.
* doc/guix.texi (Invoking guix environment): Document it.
* tests/guix-environment.sh: Add test for --ad-hoc guile-bootstrap:out.

environment: Add --system.

* guix/scripts/environment.scm (show-help, %options): Add -s/--system.
  (%default-options): Add 'system' pair.
  (guix-environment): Pass 'system' value from OPTS to 'lower-inputs'.
* doc/guix.texi (Invoking guix environment): Document it.

environment: Add only the specified outputs of the dependencies.

Before that, 'guix environment guile' (for instance) would define environment
variables that would refer to the "include" output of Bash, the "debug" output
of libgc, etc., even though these are not listed as inputs in the recipe of
'guile'.

* guix/gexp.scm (lower-inputs): Export.
* guix/scripts/environment.scm (evaluate-input-search-paths): Remove
  'derivations' parameter; add 'search-paths'.  Expect 'inputs' to be
  a list of tuples.  Adjust callers.
  (create-environment): Remove 'derivations' parameter; add 'search-paths'.
  (show-search-paths): Likewise.
  (package+propagated-inputs): New procedure.
  (packages->transitive-inputs, packages+propagated-inputs): Remove.
  (build-inputs): Expect INPUTS to be a list of derivation tuples.
  (guix-environment): Compute INPUTS using 'package+propagated-inputs',
  'package->bag', and 'bag-transitive-inputs'.  Move 'run-with-store' higher.
* tests/guix-environment.sh: Add test with FINDUTILS-BOOT0.

Merge branch 'master' into core-updates

Conflicts:
	gnu/packages/commencement.scm
	gnu/packages/xml.scm

environment: Connect to the store after the command line has been parsed.

* guix/scripts/environment.scm (guix-environment): Call 'parse-command-line'
  outside of 'with-store'.  This allows things like --help to run even if the
  daemon is not running.

Merge branch 'master' into core-updates

guix environment: Add --ad-hoc option.

* guix/scripts/environment.scm (%options): Add "ad-hoc" option.
  (show-help): Display help for "--ad-hoc".
  (packages+propagated-inputs): New procedure.
  (guix-environment): Create ad hoc environment when asked.
* doc/guix.texi ("invoking guix environment"): Document it.

Merge branch 'master' into gtk-rebuild

Conflicts:
	gnu/packages/gtk.scm

scripts: Move 'set-build-options-from-command-line*' to (guix scripts build) module.

* guix/scripts/build.scm (set-build-options-from-command-line*): New
  procedure.
* guix/scripts/environment.scm (set-build-options-from-command-line*): Delete.

ui: Deduplicate 'show-what-to-build*'.

* guix/ui.scm (show-what-to-build*): New procedure.
* guix/scripts/environment.scm (show-what-to-build*): Delete.
* guix/scripts/system.scm (show-what-to-build*): Likewise.
* build-aux/make-binary-tarball.scm (show-what-to-build*): Likewise.

environment: Move iteration outside of 'for-each-search-path'.

* guix/search-paths.scm (search-path-definition): New procedure.
* guix/scripts/environment.scm (for-each-search-path): Rename to...
  (evaluate-input-search-paths): ... this.  Remove 'proc' and 'pure?'
  parameters, and return directly the list of search-path/value pairs.
  (create-environment): Use 'for-each' and 'evaluate-input-search-paths'
  instead of 'for-each-search-path'.
  (show-search-paths): Use 'for-each', 'search-path-definition', and
  'evaluate-search-paths' instead of 'for-each-search-path'.

environment: Use 'evaluate-search-paths'.

This allows 'guix environment' to correctly handle non-directory
and/or pattern search-path specifications, such as that for
'XML_CATALOG_FILES'.

* guix/scripts/environment.scm (for-each-search-path): Use
  'evaluate-search-paths' instead of 'search-path-as-list' & co.

search-paths: Define the 'PATH' environment variable.

* guix/search-paths.scm ($PATH): New variable.
* guix/scripts/environment.scm (for-each-search-path): Use it.

environment: Use (guix search-paths).

* guix/scripts/environment.scm: Use (guix search-paths).  Fixes a
  regression introduced in e89431b.

Merge branch 'master' into core-updates