import: Add PyPI importer.

* guix/snix.scm: Delete.
* guix/import/snix.scm: New file.
* guix/import/pypi.scm: New file.
* guix/import/utils.scm: New file.
* guix/scripts/import/nix.scm: New file.
* guix/scripts/import/pypi.scm: New file.
* tests/pypi.scm: New file.
* tests/snix.scm: Import (guix import snix) module.
* guix/scripts/import.scm (%default-options, %options): Delete.
  (%standard-import-options, importers): New variables.
  (show-help): List importers.
  (guix-import): Factor out Nix-specific logic.  Delegate to correct importer
  based upon first argument.
* configure.ac (HAVE_GUILE_JSON): New conditional.
* Makefile.am (MODULES): Add new files and remove 'guix/snix.scm'.
  (SCM_TESTS): Add 'tests/pypi.scm' if guile-json is installed.

guix/scripts/import/pypi.scm

@@ -0,0 +1,83 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2014 David Thompson <davet@gnu.org>
+;;;
+;;; 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 import pypi)
+  #:use-module (guix ui)
+  #:use-module (guix utils)
+  #:use-module (guix import pypi)
+  #:use-module (guix scripts import)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-11)
+  #:use-module (srfi srfi-37)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 format)
+  #:export (guix-import-pypi))
+
+
+;;;
+;;; Command-line options.
+;;;
+
+(define %default-options
+  '())
+
+(define (show-help)
+  (display (_ "Usage: guix import pypi PACKAGE-NAME
+Import and convert the PyPI package for PACKAGE-NAME.\n"))
+  (display (_ "
+  -h, --help             display this help and exit"))
+  (display (_ "
+  -V, --version          display version information and exit"))
+  (newline)
+  (show-bug-report-information))
+
+(define %options
+  ;; Specification of the command-line options.
+  (cons* (option '(#\h "help") #f #f
+                 (lambda args
+                   (show-help)
+                   (exit 0)))
+         (option '(#\V "version") #f #f
+                 (lambda args
+                   (show-version-and-exit "guix import pypi")))
+         %standard-import-options))
+
+
+;;;
+;;; Entry point.
+;;;
+
+(define (guix-import-pypi . args)
+  (define (parse-options)
+    ;; Return the alist of option values.
+    (args-fold* args %options
+                (lambda (opt name arg result)
+                  (leave (_ "~A: unrecognized option~%") name))
+                (lambda (arg result)
+                  (alist-cons 'argument arg result))
+                %default-options))
+
+  (let* ((opts (parse-options))
+         (args (filter-map (match-lambda
+                            (('argument . value)
+                             value)
+                            (_ #f))
+                           (reverse opts))))
+    (match args
+      ((package-name)
+       (pypi->guix-package package-name)))))