fix: It found a bug!!!

#3189 (comment)

Author: dangotbanned

narwhals/_duckdb/expr.py

@@ -258,7 +258,8 @@ def is_finite(self) -> Self:
         return self._with_elementwise(lambda expr: F("isfinite", expr))
 
     def is_in(self, other: Sequence[Any]) -> Self:
-        return self._with_elementwise(lambda expr: F("contains", lit(other), expr))
+        other_ = tuple(other) if not isinstance(other, (tuple, list)) else other
+        return self._with_elementwise(lambda expr: F("contains", lit(other_), expr))
 
     def fill_null(
         self,

narwhals/_duckdb/typing.py

@@ -8,11 +8,31 @@
 from narwhals._typing_compat import TypeVar
 
 if TYPE_CHECKING:
+    import uuid
+
+    import numpy as np
+    import pandas as pd
     from duckdb import DuckDBPyConnection, Expression
     from typing_extensions import TypeAlias, TypeIs
 
+    from narwhals.typing import Into1DArray, PythonLiteral
+
+
 __all__ = ["BaseType", "WindowExpressionKwargs", "has_children", "is_dtype"]
 
+IntoDuckDBLiteral: TypeAlias = """
+    PythonLiteral
+    | dict[Any, Any]
+    | uuid.UUID
+    | bytearray
+    | memoryview
+    | Into1DArray
+    | pd.api.typing.NaTType
+    | pd.api.typing.NAType
+    | np.ma.MaskedArray
+    | duckdb.Value
+    """
+
 
 class WindowExpressionKwargs(TypedDict, total=False):
     partition_by: Sequence[str | Expression]

narwhals/_duckdb/utils.py

@@ -6,7 +6,7 @@
 import duckdb
 from duckdb import Expression
 
-from narwhals._duckdb.typing import BaseType, has_children, is_dtype
+from narwhals._duckdb.typing import BaseType, IntoDuckDBLiteral, has_children, is_dtype
 from narwhals._utils import Implementation, Version, isinstance_or_issubclass, zip_strict
 from narwhals.exceptions import ColumnNotFoundError, UnsupportedDTypeError
 
@@ -22,7 +22,7 @@
     from narwhals._duckdb.dataframe import DuckDBLazyFrame
     from narwhals._duckdb.expr import DuckDBExpr
     from narwhals.dtypes import DType
-    from narwhals.typing import IntoDType, NonNestedLiteral, TimeUnit
+    from narwhals.typing import IntoDType, TimeUnit
 
 Incomplete: TypeAlias = Any
 
@@ -54,7 +54,7 @@
 
 
 # TODO @dangotbanned: Raise an issue upstream on `Expression | str` too narrow
-def lit(value: Expression | NonNestedLiteral | Sequence[Any]) -> Expression:
+def lit(value: IntoDuckDBLiteral | Expression) -> Expression:
     """Alias for `duckdb.ConstantExpression`."""
     lit_: Incomplete = duckdb.ConstantExpression
     return lit_(value)

tests/expr_and_series/is_in_test.py

@@ -26,6 +26,18 @@ def test_expr_is_in_empty_list(constructor: Constructor) -> None:
     assert_equal_data(result, expected)
 
 
+def test_expr_is_in_iterable(
+    constructor: Constructor, request: pytest.FixtureRequest
+) -> None:
+    if any(x in str(constructor) for x in ("sqlframe", "polars")):
+        request.applymarker(pytest.mark.xfail)
+    df = nw.from_native(constructor(data))
+    sequence = 4, 2
+    result = df.select(nw.col("a").is_in(iter(sequence)))
+    expected = {"a": [False, True, True, False]}
+    assert_equal_data(result, expected)
+
+
 def test_ser_is_in(constructor_eager: ConstructorEager) -> None:
     ser = nw.from_native(constructor_eager(data), eager_only=True)["a"]
     result = {"a": ser.is_in([4, 5])}