CLN: [WIP] trial pull-request to make sure everything is in order before proceeding (GH14468)

.travis.yml

@@ -50,7 +50,7 @@ matrix:
           - python-gtk2
     - os: linux
       env:
-        - JOB="3.5" TEST_ARGS="--skip-slow --skip-network" COVERAGE=true
+        - JOB="3.5" TEST_ARGS="--skip-slow --skip-network" COVERAGE=true TYPING=true
       addons:
         apt:
           packages:
@@ -116,6 +116,7 @@ script:
   - ci/script_single.sh
   - ci/script_multi.sh
   - ci/lint.sh
+  - ci/typing.sh
   - echo "script done"
 
 after_success:

ci/install_travis.sh

@@ -114,6 +114,10 @@ if [ "$LINT" ]; then
    pip install cpplint
 fi
 
+if [ "$TYPING" ]; then
+   pip install mypy-lang
+fi
+
 if [ "$COVERAGE" ]; then
     pip install coverage pytest-cov
 fi

ci/requirements-2.7.pip

@@ -6,3 +6,4 @@ py
 PyCrypto
 mock
 ipython
+typing

ci/typing.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+echo "inside $0"
+
+source activate pandas
+
+RET=0
+
+echo "Typing  *.py"
+mypy \
+    pandas/core/base.py
+if [ $? -ne "0" ]; then
+    RET=1
+fi
+echo "Typing *.py DONE"
+
+
+exit $RET

doc/source/contributing.rst

@@ -494,8 +494,8 @@ many errors as possible, but it may not correct *all* of them. Thus, it is
 recommended that you run ``cpplint`` to double check and make any other style
 fixes manually.
 
-Python (PEP8)
-~~~~~~~~~~~~~
+Python (PEP8 and mypy)
+~~~~~~~~~~~~~~~~~~~~~~
 
 *pandas* uses the `PEP8 <http://www.python.org/dev/peps/pep-0008/>`_ standard.
 There are several tools to ensure you abide by this standard. Here are *some* of
@@ -525,6 +525,16 @@ run this slightly modified command::
 
    git diff master --name-only -- '*.py' | grep 'pandas/' | xargs flake8
 
+Pandas is gradually introducing static type annotations to the code base with
+`mypy <http://mypy.readthedocs.io/>`_. To run the checker, you'll need to install
+``mypy`` (``pip install mypy``) and run::
+
+   sh ci/typing.sh
+
+or on individual files with::
+
+   mypy path/to/module.py
+
 Backwards Compatibility
 ~~~~~~~~~~~~~~~~~~~~~~~