Add type hints

mypy.ini

@@ -0,0 +1,3 @@
+[mypy]
+follow_imports=skip
+ignore_missing_imports=True

setup.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
+import sys
 from os import path
 
 try:
@@ -12,6 +13,8 @@ readme_file = path.join(path.dirname(path.abspath(__file__)), 'README.rst')
 with open(readme_file) as readme_file:
     readme = readme_file.read()
 
+install_requires = ['typing'] if sys.version_info < (3, 6) else []
+
 setup(
     name='syncer',
     version='1.2.1',
@@ -37,4 +40,5 @@ setup(
         'Programming Language :: Python :: 3.6',
     ],
     test_suite='test_syncer',
+    install_requires=install_requires,
 )

syncer.py

@@ -2,16 +2,17 @@
 # -*- coding: utf-8 -*-
 
 import sys
-import functools
+from functools import singledispatch, wraps
 import asyncio
 import inspect
 import types
+from typing import Any, Callable, Generator
 
 
 PY35 = sys.version_info >= (3, 5)
 
 
-def _is_awaitable(co):
+def _is_awaitable(co: Generator[Any, None, Any]) -> bool:
     if PY35:
         return inspect.isawaitable(co)
     else:
@@ -19,14 +20,14 @@ def _is_awaitable(co):
                 isinstance(co, asyncio.Future))
 
 
-@functools.singledispatch
-def sync(co):
+@singledispatch
+def sync(co: Any):
     raise TypeError('Called with unsupported argument: {}'.format(co))
 
 
 @sync.register(asyncio.Future)
 @sync.register(types.GeneratorType)
-def sync_co(co):
+def sync_co(co: Generator[Any, None, Any]) -> Any:
     if not _is_awaitable(co):
         raise TypeError('Called with unsupported argument: {}'.format(co))
     return asyncio.get_event_loop().run_until_complete(co)
@@ -34,11 +35,11 @@ def sync_co(co):
 
 @sync.register(types.FunctionType)
 @sync.register(types.MethodType)
-def sync_fu(f):
+def sync_fu(f: Callable[..., Any]) -> Callable[..., Any]:
     if not asyncio.iscoroutinefunction(f):
         raise TypeError('Called with unsupported argument: {}'.format(f))
 
-    @functools.wraps(f)
+    @wraps(f)
     def run(*args, **kwargs):
         return asyncio.get_event_loop().run_until_complete(f(*args, **kwargs))
     return run

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = {py34,py35,py36}-{unittest,green,pytest,nose},flake8
+envlist = {py34,py35,py36}-{unittest,green,pytest,nose},flake8,mypy
 
 [testenv]
 changedir = {toxworkdir}
@@ -8,7 +8,7 @@ deps=
   pytest: pytest
   nose: nose
   green: green
-install = pip install -q {toxinidir}
+install = pip install {toxinidir}
 commands =
   py34-unittest: python -m unittest discover -p test*py34.py {toxinidir}/tests
   py34-green: green -p test*py34.py {toxinidir}/tests
@@ -20,10 +20,17 @@ commands =
   {py35,py36}-nose: nosetests {toxinidir}/tests
 
 [testenv:flake8]
-whitelist_externals = rm
 changedir ={toxinidir}
 basepython=python3.6
 deps=flake8
 commands=
   flake8 syncer
+
+[testenv:mypy]
+whitelist_externals = rm
+changedir ={toxinidir}
+basepython=python3.6
+deps=mypy
+commands=
+  mypy syncer.py
   rm -rf build dist **/__pycache__ **/*.pyc syncer.egg-info