Add support for Hackage

README.rst

@@ -159,6 +159,13 @@ Check `RubyGems <https://rubygems.org/>`_ for updates.
 gems
   The name used on RubyGems, e.g. ``sass``.
 
+Check Hackage
+----------
+Check `Hackage <https://hackage.haskell.org/>`_ for updates.
+
+hackage
+  The name used on Hackage, e.g. ``pandoc``.
+
 Check Local Pacman Database
 ---------------------------
 This is used when you run ``nvchecker`` on an Arch Linux system and the program always keeps up with a package in your configured repositories for `Pacman`_.

nvchecker/get_version.py

@@ -5,6 +5,7 @@ logger = logging.getLogger(__name__)
 handler_precedence = (
   'github', 'gitcafe', 'aur', 'pypi', 'archpkg', 'gems', 'pacman',
   'cmd', 'bitbucket', 'gcode_hg', 'gcode_svn', 'regex', 'manual', 'vcs',
+  'hackage',
 )
 
 def get_version(name, conf, callback):

nvchecker/source/hackage.py

@@ -0,0 +1,17 @@
+import json
+from functools import partial
+
+from tornado.httpclient import AsyncHTTPClient
+
+HACKAGE_URL = 'https://hackage.haskell.org/package/%s/preferred.json'
+
+def get_version(name, conf, callback):
+  repo = conf.get('hackage') or name
+  url = HACKAGE_URL % repo
+  AsyncHTTPClient().fetch(url, user_agent='lilydjwg/nvchecker',
+                          callback=partial(_hackage_done, name, callback))
+
+def _hackage_done(name, callback, res):
+  data = json.loads(res.body.decode('utf-8'))
+  version = data['normal-version'][0]
+  callback(name, version)