python: replace mypy by ty (#235)

* python: replace mypy by ty

* fmt

* fix strange ignore

* bitfield fix

* element property method simplification

* rm useless ty rule

* bump ty

* fix conflicts

* small simplifications

* remove useless thing

* minor cleanup related to adding ty

* refactor: avoid cast(Any, ...), be more explicit with test models + ignores

---------

Co-authored-by: fselmo <[email protected]>

Author: tcoratger

CLAUDE.md

@@ -28,11 +28,11 @@ uv run fill --fork=devnet --clean -n auto # Generate test vectors
 ### Code Quality
 
 ```bash
-uv run ruff format src tests packages      # Format code
-uv run ruff check --fix src tests packages # Lint and fix
-uvx tox -e typecheck                       # Type check
-uvx tox -e all-checks                      # All quality checks
-uvx tox                                    # Everything (checks + tests + docs)
+uv run ruff format       # Format code
+uv run ruff check --fix  # Lint and fix
+uvx tox -e typecheck     # Type check
+uvx tox -e all-checks    # All quality checks
+uvx tox                  # Everything (checks + tests + docs)
 ```
 
 ### Common Tasks

README.md

@@ -97,16 +97,16 @@ uv run fill --clean --fork=devnet
 
 ```bash
 # Check code style and errors
-uv run ruff check src tests packages
+uv run ruff check
 
 # Auto-fix issues
-uv run ruff check --fix src tests packages
+uv run ruff check --fix
 
 # Format code
-uv run ruff format src tests packages
+uv run ruff format
 
 # Type checking
-uv run mypy src tests packages
+uv run ty check
 ```
 
 ### Using Tox for Comprehensive Checks
@@ -179,24 +179,24 @@ def test_withdrawal_amount_above_uint64_max():
 - **pytest**: Testing framework - just name test files `test_*.py` and functions `test_*`
 - **uv**: Fast Python package manager - like npm/yarn but for Python
 - **ruff**: Linter and formatter
-- **mypy**: Type checker that works with Pydantic models
+- **ty**: Type checker
 - **tox**: Automation tool for running tests across multiple environments (used via `uvx`)
 - **mkdocs**: Documentation generator - write docs in Markdown, serve them locally
 
 ## Common Commands Reference
 
-| Task                                          | Command                                      |
-|-----------------------------------------------|----------------------------------------------|
-| Install and sync project and dev dependencies | `uv sync`                                    |
-| Run tests                                     | `uv run pytest ...`                          |
-| Format code                                   | `uv run ruff format src tests packages`      |
-| Lint code                                     | `uv run ruff check src tests packages`       |
-| Fix lint errors                               | `uv run ruff check --fix src tests packages` |
-| Type check                                    | `uv run mypy src tests packages`             |
-| Build docs                                    | `uv run mkdocs build`                        |
-| Serve docs                                    | `uv run mkdocs serve`                        |
-| Run everything (checks + tests + docs)        | `uvx tox`                                    |
-| Run all quality checks (no tests/docs)        | `uvx tox -e all-checks`                      |
+| Task                                          | Command                   |
+|-----------------------------------------------|---------------------------|
+| Install and sync project and dev dependencies | `uv sync`                 |
+| Run tests                                     | `uv run pytest ...`       |
+| Format code                                   | `uv run ruff format`      |
+| Lint code                                     | `uv run ruff check`       |
+| Fix lint errors                               | `uv run ruff check --fix` |
+| Type check                                    | `uv run ty check`         |
+| Build docs                                    | `uv run mkdocs build`     |
+| Serve docs                                    | `uv run mkdocs serve`     |
+| Run everything (checks + tests + docs)        | `uvx tox`                 |
+| Run all quality checks (no tests/docs)        | `uvx tox -e all-checks`   |
 
 ## Contributing
 

packages/testing/src/framework/forks/base.py

@@ -97,9 +97,9 @@ def __init_subclass__(
         cls._children = set()
 
         # Track parent-child relationships
-        base_class = cls.__bases__[0]
-        if base_class != BaseFork and hasattr(base_class, "_children"):
-            base_class._children.add(cls)
+        for base in cls.__bases__:
+            if base is not BaseFork and issubclass(base, BaseFork):
+                base._children.add(cls)
 
     @classmethod
     @abstractmethod

pyproject.toml

@@ -66,16 +66,11 @@ known-first-party = ["lean_spec"]
 [tool.ruff.lint.per-file-ignores]
 "tests/**" = ["D", "F401", "F403"]
 
-[tool.mypy]
-python_version = "3.12"
-plugins = ["pydantic.mypy"]
-strict = true
-warn_return_any = true
-warn_unused_configs = true
-warn_unused_ignores = true
-no_implicit_reexport = true
-namespace_packages = false
-explicit_package_bases = false
+[tool.ty.environment]
+python-version = "3.12"
+
+[tool.ty.terminal]
+error-on-warning = true
 
 [tool.pytest.ini_options]
 minversion = "8.3.3"
@@ -125,7 +120,7 @@ test = [
     "lean-ethereum-testing",
 ]
 lint = [
-    "mypy>=1.17.0,<2",
+    "ty>=0.0.1a34",
     "ruff>=0.13.2,<1",
     "codespell>=2.4.1,<3",
 ]

src/lean_spec/subspecs/containers/attestation/types.py

@@ -59,7 +59,7 @@ def to_validator_indices(self) -> list[Uint64]:
         return indices
 
 
-class NaiveAggregatedSignature(SSZList):
+class NaiveAggregatedSignature(SSZList[Signature]):
     """Naive list of validator signatures used for aggregation placeholders."""
 
     ELEMENT_TYPE = Signature

src/lean_spec/subspecs/containers/block/types.py

@@ -6,18 +6,12 @@
 from ..attestation import AggregatedAttestation, AttestationData, NaiveAggregatedSignature
 
 
-class AggregatedAttestations(SSZList):
+class AggregatedAttestations(SSZList[AggregatedAttestation]):
     """List of aggregated attestations included in a block."""
 
     ELEMENT_TYPE = AggregatedAttestation
     LIMIT = int(VALIDATOR_REGISTRY_LIMIT)
 
-    def __getitem__(self, index: int) -> AggregatedAttestation:
-        """Access an aggregated attestation by index with proper typing."""
-        item = self.data[index]
-        assert isinstance(item, AggregatedAttestation)
-        return item
-
     def has_duplicate_data(self) -> bool:
         """Check if any two attestations share the same AttestationData."""
         seen: set[AttestationData] = set()
@@ -28,7 +22,7 @@ def has_duplicate_data(self) -> bool:
         return False
 
 
-class AttestationSignatures(SSZList):
+class AttestationSignatures(SSZList[NaiveAggregatedSignature]):
     """List of per-attestation naive signature lists aligned with block body attestations."""
 
     ELEMENT_TYPE = NaiveAggregatedSignature

src/lean_spec/subspecs/containers/state/state.py

@@ -333,8 +333,8 @@ def process_block_header(self, block: Block) -> "State":
             update={
                 "latest_justified": new_latest_justified,
                 "latest_finalized": new_latest_finalized,
-                "historical_block_hashes": HistoricalBlockHashes(data=new_historical_hashes_data),
-                "justified_slots": JustifiedSlots(data=new_justified_slots_data),
+                "historical_block_hashes": new_historical_hashes_data,
+                "justified_slots": new_justified_slots_data,
                 "latest_block_header": new_header,
             }
         )
@@ -570,7 +570,7 @@ def process_attestations(
                 "justifications_validators": JustificationValidators(
                     data=[vote for root in sorted_roots for vote in justifications[root]]
                 ),
-                "justified_slots": JustifiedSlots(data=justified_slots),
+                "justified_slots": justified_slots,
                 "latest_justified": latest_justified,
                 "latest_finalized": latest_finalized,
             }

src/lean_spec/subspecs/containers/state/types.py

@@ -7,14 +7,14 @@
 from ..validator import Validator
 
 
-class HistoricalBlockHashes(SSZList):
+class HistoricalBlockHashes(SSZList[Bytes32]):
     """List of historical block root hashes up to historical_roots_limit."""
 
     ELEMENT_TYPE = Bytes32
     LIMIT = int(DEVNET_CONFIG.historical_roots_limit)
 
 
-class JustificationRoots(SSZList):
+class JustificationRoots(SSZList[Bytes32]):
     """List of justified block roots up to historical_roots_limit."""
 
     ELEMENT_TYPE = Bytes32
@@ -33,14 +33,8 @@ class JustificationValidators(BaseBitlist):
     LIMIT = int(DEVNET_CONFIG.historical_roots_limit) * int(DEVNET_CONFIG.validator_registry_limit)
 
 
-class Validators(SSZList):
+class Validators(SSZList[Validator]):
     """Validator registry tracked in the state."""
 
     ELEMENT_TYPE = Validator
     LIMIT = int(DEVNET_CONFIG.validator_registry_limit)
-
-    def __getitem__(self, index: int) -> Validator:
-        """Access a validator by index with proper typing."""
-        item = self.data[index]
-        assert isinstance(item, Validator)
-        return item

src/lean_spec/subspecs/networking/config.py

@@ -7,8 +7,8 @@
 MAX_REQUEST_BLOCKS: Final = 2**10
 """Maximum number of blocks in a single request."""
 
-MESSAGE_DOMAIN_INVALID_SNAPPY: Final = DomainType(b"\x00\x00\x00\x00")
+MESSAGE_DOMAIN_INVALID_SNAPPY: Final[DomainType] = b"\x00\x00\x00\x00"
 """4-byte domain for gossip message-id isolation of invalid snappy messages."""
 
-MESSAGE_DOMAIN_VALID_SNAPPY: Final = DomainType(b"\x01\x00\x00\x00")
+MESSAGE_DOMAIN_VALID_SNAPPY: Final[DomainType] = b"\x01\x00\x00\x00"
 """4-byte domain for gossip message-id isolation of valid snappy messages."""

src/lean_spec/subspecs/networking/gossipsub/message.py

@@ -83,8 +83,8 @@ def id(self) -> MessageId:
                 self.raw_data,
             )
 
-        # Compute the raw ID bytes and cast to our strict type before caching
-        self._id = MessageId(self._compute_raw_id(domain, data_for_hash))
+        # Compute the raw ID bytes and assign with proper type annotation
+        self._id: MessageId = self._compute_raw_id(domain, data_for_hash)
         return self._id
 
     def _compute_raw_id(self, domain: bytes, message_data: bytes) -> bytes: