guix package: Add 'guix show' alias.

* guix/scripts/show.scm: New file.
* Makefile.am (MODULES): Add it.
* po/guix/POTFILES.in: Add it.
* tests/guix-package-aliases.sh: Add test.
* doc/guix.texi (Invoking guix package): Document it and use it in a example.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

Makefile.am

@@ -241,6 +241,7 @@ MODULES =					\
   guix/scripts/remove.scm			\
   guix/scripts/upgrade.scm			\
   guix/scripts/search.scm			\
+  guix/scripts/show.scm				\
   guix/scripts/gc.scm				\
   guix/scripts/hash.scm				\
   guix/scripts/pack.scm				\

doc/guix.texi

@@ -2657,7 +2657,9 @@ For your convenience, we also provide the following aliases:
 @item
 @command{guix remove} is an alias for @command{guix package -r},
 @item
-and @command{guix upgrade} is an alias for @command{guix package -u}.
+@command{guix upgrade} is an alias for @command{guix package -u},
+@item
+and @command{guix show} is an alias for @command{guix package --show=}.
 @end itemize
 
 These aliases are less expressive than @command{guix package} and provide
@@ -3020,9 +3022,9 @@ version: 3.3.5
 @end example
 
 You may also specify the full name of a package to only get details about a
-specific version of it:
+specific version of it (this time using the @command{guix show} alias):
 @example
-$ guix package --show=python@@3.4 | recsel -p name,version
+$ guix show python@@3.4 | recsel -p name,version
 name: python
 version: 3.4.3
 @end example

guix/scripts/show.scm

@@ -0,0 +1,67 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2019 Simon Tournier <zimon.toutoune@gmail.com>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix scripts show)
+  #:use-module (guix ui)
+  #:use-module (guix scripts package)
+  #:use-module (guix scripts)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-37)
+  #:export (guix-show))
+
+(define (show-help)
+  (display (G_ "Usage: guix show [OPTION] PACKAGE...
+Show details about PACKAGE."))
+  (display (G_"
+This is an alias for 'guix package --show='.\n"))
+  (newline)
+  (display (G_ "
+  -h, --help             display this help and exit"))
+  (display (G_ "
+  -V, --version          display version information and exit"))
+  (newline)
+  (show-bug-report-information))
+
+(define %options
+  ;; Specification of the command-line options.
+  (list (option '(#\h "help") #f #f
+                (lambda args
+                  (show-help)
+                  (exit 0)))
+        (option '(#\V "version") #f #f
+                (lambda args
+                  (show-version-and-exit "guix show")))))
+
+(define (guix-show . args)
+  (define (handle-argument arg result)
+    ;; Treat all non-option arguments as regexps.
+    (cons `(query show ,arg)
+          result))
+
+  (define opts
+    (args-fold* args %options
+                (lambda (opt name arg . rest)
+                  (leave (G_ "~A: unrecognized option~%") name))
+                handle-argument
+                '()))
+
+  (unless (assoc-ref opts 'query)
+    (leave (G_ "missing arguments: no package to show~%")))
+
+  (guix-package* opts))

po/guix/POTFILES.in

@@ -47,6 +47,7 @@ guix/scripts/install.scm
 guix/scripts/remove.scm
 guix/scripts/upgrade.scm
 guix/scripts/search.scm
+guix/scripts/show.scm
 guix/scripts/gc.scm
 guix/scripts/hash.scm
 guix/scripts/import.scm

tests/guix-package-aliases.sh

@@ -58,3 +58,7 @@ if guix remove -i guile-bootstrap -p "$profile" --bootstrap
 then false; else true; fi
 
 guix search '\<board\>' game | grep '^name: gnubg'
+
+guix show --version
+guix show guile
+guix show python@3 | grep "^name: python"