Drop support for Python 3.9

Author: davidfstr

.github/copilot-instructions.md

@@ -10,7 +10,7 @@ Single-file implementation in `trycast/__init__.py` (~1300 lines).
 
 ### Version Compatibility Strategy
 
-**Critical**: trycast supports Python 3.9-3.13 with extensive conditional imports:
+**Critical**: trycast supports Python 3.10-3.13 with extensive conditional imports:
 - Use `sys.version_info >= (major, minor)` checks to conditionally import features
 - Import from `typing_extensions` as fallback for older Python versions
 - Example pattern (lines 43-50, 53-65, 67-77):
@@ -56,7 +56,7 @@ When adding features, test against all typecheckers: `make typecheck` runs mypy,
 
 ### Testing Commands (Makefile)
 - `make test` - Run unittest against current Python version
-- `make testall` - Run tox across Python 3.9-3.13 (uses venv3.9/, venv3.10/, etc.)
+- `make testall` - Run tox across Python 3.10-3.13 (uses venv3.10/, venv3.11/, etc.)
 - `make typecheck` - Run all typecheckers (mypy, pyright, pyre)
 - `make format` - Format with black + isort
 - `make lint` - Check black/isort/flake8 compliance
@@ -72,7 +72,7 @@ When adding features, test against all typecheckers: `make typecheck` runs mypy,
   - Example: `python -m timeit -s 'from benchmarks import http_request_parsing_example__fail as b' 'b.run()'`
 
 ### Virtual Environments
-Multiple venvs for each Python version: `venv3.9/`, `venv3.10/`, ..., `venv3.13/`. Use Poetry for dependency management.
+Multiple venvs for each Python version: `venv3.10/`, `venv3.11/`, ..., `venv3.13/`. Use Poetry for dependency management.
 
 ## Critical Patterns
 

.github/workflows/ci.yaml

@@ -7,7 +7,7 @@ jobs:
       matrix:
         # All available versions of Python:
         # https://github.com/actions/python-versions/blob/main/versions-manifest.json
-        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.10", "3.11", "3.12", "3.13"]
       fail-fast: false
     steps:
       - name: Checkout code

README.md

@@ -217,7 +217,6 @@ python -m pip install trycast
 
 - So that `trycast()` can recognize TypedDicts with mixed required and
   not-required keys correctly:
-    * Use Python 3.9+.
     * Prefer using `typing.TypedDict` instead of `typing_extensions.TypedDict`.
 
 
@@ -514,7 +513,7 @@ raised exceptions, and other details.
 
 ### main (v2.0.0)
 
-* Drop support for Python 3.8.
+* Drop support for Python 3.8 and Python 3.9.
     * Drop support for Python 3.8's neutered TypedDict,
       which lacks metadata present in later versions.
 * Drop support for Pytype type checker, since it has been 

poetry.lock

@@ -16,7 +16,6 @@ classifiers = [  # https://pypi.org/classifiers/
     "License :: OSI Approved :: MIT License",
     "Operating System :: OS Independent",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
@@ -29,7 +28,7 @@ classifiers = [  # https://pypi.org/classifiers/
 "Release notes" = "https://github.com/davidfstr/trycast#changelog"
 
 [tool.poetry.dependencies]
-python = ">=3.9"
+python = ">=3.10"
 
 [tool.poetry.group.dev.dependencies]
 mypy = "*"
@@ -84,7 +83,7 @@ line_length = 88
 legacy_tox_ini = """
 
 [tox]
-envlist = py39,py310,py311,py312,py313
+envlist = py310,py311,py312,py313
 isolated_build = True
 
 [testenv]

pyproject.toml

@@ -2724,16 +2724,11 @@ def assertRaisesEqual(
         else:
             self.fail(f"Expected {tp}")
 
+    # TODO: Inline unique implementation
     @staticmethod
     def _typing_error_messages(template: str) -> List[str]:
-        python_3_9 = (
-            template.replace("Literal", "typing.Literal")
-            .replace("NoReturn", "typing.NoReturn")
-            .replace("Union", "typing.Union")
-        )
         return [
             template,
-            python_3_9,  # for Python 3.9
         ]
 
 

tests.py

@@ -146,19 +146,8 @@ def _is_typed_dict(tp: object) -> bool:
 
 
 # _is_newtype
-if NewType.__class__.__name__ == "function":  # type: ignore[reportGeneralTypeIssues]  # pyright
-    # Python 3.9
-    def _is_newtype(tp: object) -> bool:
-        return (
-            hasattr(tp, "__class__")
-            and tp.__class__.__name__ == "function"
-            and hasattr(tp, "__qualname__")
-            and tp.__qualname__.startswith("NewType.<locals>")  # type: ignore[attr-defined]
-            and hasattr(tp, "__module__")
-            and tp.__module__ == "typing"
-        )
-
-elif NewType.__class__.__name__ == "type":  # type: ignore[reportGeneralTypeIssues]  # pyright
+# TODO: Inline unique implementation
+if NewType.__class__.__name__ == "type":  # type: ignore[reportGeneralTypeIssues]  # pyright
     # Python 3.10+
     def _is_newtype(tp: object) -> bool:
         return isinstance(tp, NewType)  # type: ignore[arg-type]