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chore: switch from mypy to ty for Python type checking #5761

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Merged
max-sixty merged 5 commits into from
Apr 1, 2026
+40 −90
Merged

chore: switch from mypy to ty for Python type checking #5761

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6598360
chore: bump mypy from 1.18.1 to 1.19.1 in /prqlc/bindings/prqlc-python
dependabot[bot] Mar 31, 2026
909523d
chore: switch from mypy to ty for Python type checking
prql-bot Apr 1, 2026
c01d495
fix: configure ty for native extension module
prql-bot Apr 1, 2026
79bc9be
fix: revert test import, suppress ty submodule warning in config
prql-bot Apr 1, 2026
dde763f
fix: use correct ty rules config syntax
prql-bot Apr 1, 2026
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2 changes: 1 addition & 1 deletion prqlc/bindings/prqlc-python/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -130,7 +130,7 @@ For development, we use `uv` for fast dependency management:
uv run pytest

# Run type checking
uv run mypy
uv run ty check

# Or use the task runner
task test
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6 changes: 3 additions & 3 deletions prqlc/bindings/prqlc-python/noxfile.py
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Expand Up @@ -29,7 +29,7 @@ def _install_prqlc(session: Session) -> None:
"prqlc",
)
# Install dev dependencies separately since we're using dependency-groups
session.install("pytest>=7", "mypy==1.18.1")
session.install("pytest>=7", "ty>=0.0.27")


@nox.session(python=VERSIONS) # type: ignore[misc]
Expand All @@ -42,6 +42,6 @@ def tests(session: Session) -> None:

@nox.session(python=VERSIONS) # type: ignore[misc]
def typing(session: Session) -> None:
"""Check types with mypy"""
"""Check types with ty"""
_install_prqlc(session)
session.run("mypy")
session.run("ty", "check")
23 changes: 9 additions & 14 deletions prqlc/bindings/prqlc-python/pyproject.toml
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Expand Up @@ -30,9 +30,17 @@ python-source = "python"
[dependency-groups]
dev = [
"pytest >= 7",
"mypy == 1.18.1",
"ty>=0.0.27",
]

[tool.ty.src]
# noxfile.py is build infrastructure, not part of the package
exclude = ["noxfile.py"]

[tool.ty.rules]
# prqlc.debug is a native PyO3 submodule, not a Python subpackage
possibly-missing-submodule = "ignore"

[tool.ruff]
fix = true
ignore = [
Expand All @@ -41,16 +49,3 @@ ignore = [
# No lambdas — too strict
"E731",
]

[tool.mypy]
files = "."
show_error_codes = true
strict = true
warn_unused_ignores = true

[[tool.mypy.overrides]]
ignore_missing_imports = true
module = [
"pytest.*",
"nox.*",
]
2 changes: 1 addition & 1 deletion prqlc/bindings/prqlc-python/python/prqlc/__init__.py
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@@ -1,7 +1,7 @@
# ruff: noqa: F403, F405
#
# This is the default module init provided automatically by Maturin.
from .prqlc import *
from .prqlc import * # ty: ignore[unresolved-import]
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@max-sixty max-sixty Apr 1, 2026

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does this prevent all type checking?!

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@prql-bot prql-bot Apr 1, 2026

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No — ty: ignore[unresolved-import] only suppresses the unresolved-import diagnostic on that single line. All other type checking remains active. The .prqlc module is a native PyO3 extension that only exists after Maturin builds it, so ty can't resolve the import statically — same reason the old mypy config had ignore_missing_imports = true for similar cases.

The pyproject.toml config also sets possibly-missing-submodule = "ignore" for prqlc.debug (another native submodule), but everything else is checked normally.

That said, if you'd prefer a different approach — like a stub file or removing the ignore — happy to adjust.


__doc__ = prqlc.__doc__
if hasattr(prqlc, "__all__"):
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