Support tuple items in map

[jolovicdev]

Summary

• Move map() task construction into the shared batch helper
• Allow tuple items passed to map() to be used as positional arguments
• Add sync and async coverage for tuple-item map calls

Testing

• uv run ruff check src/ tests/
• uv run pyright src/
• uv run pytest tests/ -v

[ds-review]

PR Review

PR: Support tuple items in map

Important

Verdict: Request changes - 6 actionable findings, highest severity P1.

Findings (6)

Breaking change: tuple items now unpacked automatically

src/cashet/_batch.py:85

The new logic in build_map_tasks unpacks any tuple item with *item, treating each element as a separate positional argument. This silently breaks callers who previously used map with tuple items that were meant to be passed as a single argument. The old behavior treated item as a single argument regardless of type. Consider documenting this as a breaking change or adding a parameter to control unpacking.

Namedtuple items incorrectly unpacked

src/cashet/_batch.py:85

Namedtuples are instances of tuple, so isinstance(item, tuple) is True. Passing a list of namedtuples will unpack each field as separate arguments, which is probably not the intended behavior. Users might expect namedtuples to be treated as single items. Either document this as intentional or change the check to isinstance(item, tuple) and not namedtuple.

Empty tuple items lead to missing arguments

src/cashet/_batch.py:85

If an empty tuple () is passed as an item, *item expands to nothing, so the resulting task will have only the extra *args and kwargs, likely causing TypeError for functions that require at least one positional argument. The previous behavior passed the empty tuple as a single argument. This edge case may cause unexpected errors.

build_map_tasks lacks docstring

src/cashet/_batch.py:78

The function should include a docstring explaining its behavior, especially the tuple unpacking logic, to help maintainability.

Imprecise return type in build_map_tasks

src/cashet/_batch.py:83

The return type is list[Any], which loses information. Consider using list[tuple[Callable[..., Any], tuple[Any, ...], dict[str, Any]]] for better type safety.

Missing edge case tests for tuple unpacking

tests/test_map.py:46

The new test only covers a tuple of two elements. Consider adding tests for empty tuple, single-element tuple, and mixed non-tuple/tuple items to ensure correctness.

How To Recheck

Reply @ds-review recheck under the relevant inline finding after pushing a fix.

[ds-review]

Breaking change: tuple items now unpacked automatically

The new logic in build_map_tasks unpacks any tuple item with *item, treating each element as a separate positional argument. This silently breaks callers who previously used map with tuple items that were meant to be passed as a single argument. The old behavior treated item as a single argument regardless of type. Consider documenting this as a breaking change or adding a parameter to control unpacking.

[ds-review]

Namedtuple items incorrectly unpacked

Namedtuples are instances of tuple, so isinstance(item, tuple) is True. Passing a list of namedtuples will unpack each field as separate arguments, which is probably not the intended behavior. Users might expect namedtuples to be treated as single items. Either document this as intentional or change the check to isinstance(item, tuple) and not namedtuple.

[ds-review]

Empty tuple items lead to missing arguments

If an empty tuple () is passed as an item, *item expands to nothing, so the resulting task will have only the extra *args and kwargs, likely causing TypeError for functions that require at least one positional argument. The previous behavior passed the empty tuple as a single argument. This edge case may cause unexpected errors.

[ds-review]

build_map_tasks lacks docstring

The function should include a docstring explaining its behavior, especially the tuple unpacking logic, to help maintainability.

[ds-review]

Imprecise return type in build_map_tasks

The return type is list[Any], which loses information. Consider using list[tuple[Callable[..., Any], tuple[Any, ...], dict[str, Any]]] for better type safety.

Suggested change

	) -> list[Any]:
	) -> list[tuple[Callable[..., Any], tuple[Any, ...], dict[str, Any]]]:

[ds-review]

Missing edge case tests for tuple unpacking

The new test only covers a tuple of two elements. Consider adding tests for empty tuple, single-element tuple, and mixed non-tuple/tuple items to ensure correctness.