Mypy type checking

Makefile

@@ -6,6 +6,7 @@ pytest:
 
 type:
  pytype -j auto
+ MYPY_FORCE_COLOR=1 mypy ${LINT_PATHS}
 
 lint:
  # stop the build if there are Python syntax errors or undefined names

docs/conf.py

@@ -13,6 +13,7 @@
 #
 import os
 import sys
+from typing import Dict, List
 from unittest.mock import MagicMock
 
 # We CANNOT enable 'sphinxcontrib.spelling' because ReadTheDocs.org does not support
@@ -37,7 +38,7 @@
 
 
 class Mock(MagicMock):
- __subclasses__ = []
+ __subclasses__ = [] # type: ignore
 
  @classmethod
  def __getattr__(cls, name):
@@ -48,7 +49,7 @@ def __getattr__(cls, name):
 # Note: because of that we cannot test examples using CI
 # 'torch', 'torch.nn', 'torch.nn.functional',
 # DO not mock modules for now, we will need to do that for read the docs later
-MOCK_MODULES = []
+MOCK_MODULES: List[str] = []
 sys.modules.update((mod_name, Mock()) for mod_name in MOCK_MODULES)
 
 # Read version from file
@@ -171,7 +172,7 @@ def setup(app):
 
 # -- Options for LaTeX output ------------------------------------------------
 
-latex_elements = {
+latex_elements: Dict[str, str] = {
  # The paper size ('letterpaper' or 'a4paper').
  #
  # 'papersize': 'letterpaper',

setup.cfg

@@ -25,6 +25,58 @@ markers =
 inputs = stable_baselines3
 disable = pyi-error
 
+[mypy]
+ignore_missing_imports = True
+exclude = (?x)(
+ stable_baselines3/a2c/a2c.py$
+ | stable_baselines3/common/atari_wrappers.py$
+ | stable_baselines3/common/base_class.py$
+ | stable_baselines3/common/buffers.py$
+ | stable_baselines3/common/callbacks.py$
+ | stable_baselines3/common/distributions.py$
+ | stable_baselines3/common/env_util.py$
+ | stable_baselines3/common/envs/bit_flipping_env.py$
+ | stable_baselines3/common/envs/identity_env.py$
+ | stable_baselines3/common/envs/multi_input_envs.py$
+ | stable_baselines3/common/logger.py$
+ | stable_baselines3/common/monitor.py$
+ | stable_baselines3/common/off_policy_algorithm.py$
+ | stable_baselines3/common/on_policy_algorithm.py$
+ | stable_baselines3/common/policies.py$
+ | stable_baselines3/common/preprocessing.py$
+ | stable_baselines3/common/save_util.py$
+ | stable_baselines3/common/sb2_compat/rmsprop_tf_like.py$
+ | stable_baselines3/common/torch_layers.py$
+ | stable_baselines3/common/type_aliases.py$
+ | stable_baselines3/common/utils.py$
+ | stable_baselines3/common/vec_env/__init__.py$
+ | stable_baselines3/common/vec_env/base_vec_env.py$
+ | stable_baselines3/common/vec_env/dummy_vec_env.py$
+ | stable_baselines3/common/vec_env/stacked_observations.py$
+ | stable_baselines3/common/vec_env/subproc_vec_env.py$
+ | stable_baselines3/common/vec_env/util.py$
+ | stable_baselines3/common/vec_env/vec_check_nan.py$
+ | stable_baselines3/common/vec_env/vec_extract_dict_obs.py$
+ | stable_baselines3/common/vec_env/vec_frame_stack.py$
+ | stable_baselines3/common/vec_env/vec_monitor.py$
+ | stable_baselines3/common/vec_env/vec_normalize.py$
+ | stable_baselines3/common/vec_env/vec_transpose.py$
+ | stable_baselines3/common/vec_env/vec_video_recorder.py$
+ | stable_baselines3/dqn/dqn.py$
+ | stable_baselines3/dqn/policies.py$
+ | stable_baselines3/her/her_replay_buffer.py$
+ | stable_baselines3/ppo/ppo.py$
+ | stable_baselines3/sac/policies.py$
+ | stable_baselines3/sac/sac.py$
+ | stable_baselines3/td3/policies.py$
+ | stable_baselines3/td3/td3.py$
+ | tests/test_distributions.py$
+ | tests/test_logger.py$
+ | tests/test_tensorboard.py$
+ | tests/test_train_eval_mode.py$
+ | tests/test_vec_normalize.py$
+ )
+
 [flake8]
 ignore = W503,W504,E203,E231 # line breaks before and after binary operators
 # Ignore import not used when aliases are defined

setup.py

@@ -94,6 +94,7 @@
  "pytest-xdist",
  # Type check
  "pytype",
+ "mypy",
  # Lint code
  "flake8>=3.8",
  # Find likely bugs