Embed type hints, check with mypy

.github/workflows/build.yml

@@ -89,6 +89,22 @@ jobs:
       - name: ruff format
         run: ruff format --check
 
+  type:
+    name: Type
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - name: Setup Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: 3.14
+      - name: Install dependencies
+        run: python -m pip install -r requirements-type.txt
+      - name: Create _version.py
+        run: echo '__version__ = ""' > src/pyzstd/_version.py
+      - name: mypy
+        run: mypy
+
   publish:
     name: Publish to PyPI
     if: startsWith(github.ref, 'refs/tags')

CHANGELOG.md

@@ -11,6 +11,7 @@ All notable changes to this project will be documented in this file.
 - Remove git submodule usage
 - Drop support for Python 3.9 and below
 - Use `ruff` as formatter and linter
+- Embed type hints in Python code, and check with `mypy`
 
 ## 0.18.0 (October 5, 2025)
 

pyproject.toml

@@ -60,22 +60,60 @@ version-file = "src/pyzstd/_version.py"
 source = "vcs"
 
 
+#
+# mypy
+#
+
+[tool.mypy]
+# Import discovery
+files = "src"
+ignore_missing_imports = false
+follow_imports = "normal"
+# Platform configuration
+python_version = "3.14"
+# Disallow dynamic typing
+disallow_any_unimported = true
+disallow_any_decorated = true
+disallow_any_generics = true
+disallow_subclassing_any = true
+# Untyped definitions and calls
+disallow_untyped_calls = true
+disallow_untyped_defs = true
+disallow_incomplete_defs = true
+check_untyped_defs = true
+disallow_untyped_decorators = true
+# None and Optional handling
+no_implicit_optional = true
+strict_optional = true
+# Configuring warning
+warn_redundant_casts = true
+warn_unused_ignores = true
+warn_no_return = true
+warn_return_any = true
+warn_unreachable = true
+# Suppressing errors
+ignore_errors = false
+# Miscellaneous strictness flags
+strict_equality = true
+# Configuring error messages
+show_error_context = true
+show_error_codes = true
+# Miscellaneous
+warn_unused_configs = true
+
+
 #
 # ruff
 #
 
 [tool.ruff]
 src = ["src"]
 target-version = "py310"
-extend-exclude = [
-    "tests",
-    '*.pyi', # FIXME
-]
+extend-exclude = ["tests"]
 
 [tool.ruff.lint]
 select = ["ALL"]
 ignore = [
-    "ANN",     # FIXME
     "C901",
     "COM812",
     "D",

requirements-dev.txt

@@ -1,3 +1,4 @@
 -e .
 
 -r requirements-lint.txt
+-r requirements-type.txt

requirements-type.txt

@@ -0,0 +1 @@
+mypy==1.19.0