From f87ec466cf30a8580417ef7604c424ccdb278a97 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Sat, 6 Sep 2025 11:48:15 +0100
Subject: [PATCH 1/6] chore: enable reportIncompatibleMethodOverride in pyright

---
 narwhals/_arrow/series.py         |  4 ++--
 narwhals/_dask/expr.py            | 20 ++++++--------------
 narwhals/_duckdb/expr.py          |  4 ++--
 narwhals/_ibis/expr.py            | 12 ++++++++----
 narwhals/_ibis/expr_dt.py         |  4 ++--
 narwhals/_polars/dataframe.py     |  4 ++--
 narwhals/_spark_like/dataframe.py |  1 +
 narwhals/_spark_like/expr.py      |  8 ++++----
 narwhals/_sql/expr.py             | 21 ++++++---------------
 narwhals/dataframe.py             | 14 +++++++-------
 narwhals/stable/v1/__init__.py    |  4 ++--
 narwhals/stable/v2/__init__.py    |  4 ++--
 pyproject.toml                    |  1 +
 13 files changed, 45 insertions(+), 56 deletions(-)

diff --git a/narwhals/_arrow/series.py b/narwhals/_arrow/series.py
index eaae0353b3..ad35218148 100644
--- a/narwhals/_arrow/series.py
+++ b/narwhals/_arrow/series.py
@@ -373,12 +373,12 @@ def shift(self, n: int) -> Self:
             return self._with_native(self.native)
         return self._with_native(pa.concat_arrays(arrays))
 
-    def std(self, ddof: int, *, _return_py_scalar: bool = True) -> float:
+    def std(self, *, ddof: int, _return_py_scalar: bool = True) -> float:
         return maybe_extract_py_scalar(
             pc.stddev(self.native, ddof=ddof), _return_py_scalar
         )
 
-    def var(self, ddof: int, *, _return_py_scalar: bool = True) -> float:
+    def var(self, *, ddof: int, _return_py_scalar: bool = True) -> float:
         return maybe_extract_py_scalar(
             pc.variance(self.native, ddof=ddof), _return_py_scalar
         )
diff --git a/narwhals/_dask/expr.py b/narwhals/_dask/expr.py
index 2ff2958d43..daf097ae1a 100644
--- a/narwhals/_dask/expr.py
+++ b/narwhals/_dask/expr.py
@@ -298,14 +298,14 @@ def min(self) -> Self:
     def max(self) -> Self:
         return self._with_callable(lambda expr: expr.max().to_series(), "max")
 
-    def std(self, ddof: int) -> Self:
+    def std(self, *, ddof: int) -> Self:
         return self._with_callable(
             lambda expr: expr.std(ddof=ddof).to_series(),
             "std",
             scalar_kwargs={"ddof": ddof},
         )
 
-    def var(self, ddof: int) -> Self:
+    def var(self, *, ddof: int) -> Self:
         return self._with_callable(
             lambda expr: expr.var(ddof=ddof).to_series(),
             "var",
@@ -682,18 +682,10 @@ def str(self) -> DaskExprStringNamespace:
     def dt(self) -> DaskExprDateTimeNamespace:
         return DaskExprDateTimeNamespace(self)
 
-    arg_max: not_implemented = not_implemented()
-    arg_min: not_implemented = not_implemented()
-    arg_true: not_implemented = not_implemented()
-    ewm_mean: not_implemented = not_implemented()
-    gather_every: not_implemented = not_implemented()
-    head: not_implemented = not_implemented()
-    map_batches: not_implemented = not_implemented()
-    sample: not_implemented = not_implemented()
-    rank: not_implemented = not_implemented()
-    replace_strict: not_implemented = not_implemented()
-    sort: not_implemented = not_implemented()
-    tail: not_implemented = not_implemented()
+    ewm_mean = not_implemented()
+    map_batches = not_implemented()
+    rank = not_implemented()
+    replace_strict = not_implemented()
 
     # namespaces
     list: not_implemented = not_implemented()  # type: ignore[assignment]
diff --git a/narwhals/_duckdb/expr.py b/narwhals/_duckdb/expr.py
index cc0112159d..cab9d51f22 100644
--- a/narwhals/_duckdb/expr.py
+++ b/narwhals/_duckdb/expr.py
@@ -188,7 +188,7 @@ def func(expr: Expression) -> Expression:
     def len(self) -> Self:
         return self._with_callable(lambda _expr: F("count"))
 
-    def std(self, ddof: int) -> Self:
+    def std(self, *, ddof: int) -> Self:
         if ddof == 0:
             return self._with_callable(lambda expr: F("stddev_pop", expr))
         if ddof == 1:
@@ -204,7 +204,7 @@ def _std(expr: Expression) -> Expression:
 
         return self._with_callable(_std)
 
-    def var(self, ddof: int) -> Self:
+    def var(self, *, ddof: int) -> Self:
         if ddof == 0:
             return self._with_callable(lambda expr: F("var_pop", expr))
         if ddof == 1:
diff --git a/narwhals/_ibis/expr.py b/narwhals/_ibis/expr.py
index 17e372c3bb..90d8f42482 100644
--- a/narwhals/_ibis/expr.py
+++ b/narwhals/_ibis/expr.py
@@ -79,7 +79,7 @@ def _window_expression(
         self,
         expr: ir.Value,
         partition_by: Sequence[str | ir.Value] = (),
-        order_by: Sequence[str | ir.Column] = (),
+        order_by: Sequence[str | ir.Value] = (),
         rows_start: int | None = None,
         rows_end: int | None = None,
         *,
@@ -96,7 +96,11 @@ def _window_expression(
             rows_between = {}
         window = ibis.window(
             group_by=partition_by,
-            order_by=self._sort(*order_by, descending=descending, nulls_last=nulls_last),
+            order_by=self._sort(
+                *cast("Sequence[ir.Column]", order_by),
+                descending=descending,
+                nulls_last=nulls_last,
+            ),
             **rows_between,
         )
         return expr.over(window)
@@ -217,7 +221,7 @@ def func(df: IbisLazyFrame) -> Sequence[ir.IntegerScalar]:
             version=self._version,
         )
 
-    def std(self, ddof: int) -> Self:
+    def std(self, *, ddof: int) -> Self:
         def _std(expr: ir.NumericColumn, ddof: int) -> ir.Value:
             if ddof == 0:
                 return expr.std(how="pop")
@@ -230,7 +234,7 @@ def _std(expr: ir.NumericColumn, ddof: int) -> ir.Value:
 
         return self._with_callable(lambda expr: _std(expr, ddof))
 
-    def var(self, ddof: int) -> Self:
+    def var(self, *, ddof: int) -> Self:
         def _var(expr: ir.NumericColumn, ddof: int) -> ir.Value:
             if ddof == 0:
                 return expr.var(how="pop")
diff --git a/narwhals/_ibis/expr_dt.py b/narwhals/_ibis/expr_dt.py
index 3ee28f481d..7d98dba0df 100644
--- a/narwhals/_ibis/expr_dt.py
+++ b/narwhals/_ibis/expr_dt.py
@@ -58,8 +58,8 @@ def truncate(self, every: str) -> IbisExpr:
             fn = self._truncate(UNITS_DICT_TRUNCATE[unit])
         return self.compliant._with_callable(fn)
 
-    def offset_by(self, every: str) -> IbisExpr:
-        interval = Interval.parse_no_constraints(every)
+    def offset_by(self, by: str) -> IbisExpr:
+        interval = Interval.parse_no_constraints(by)
         unit = interval.unit
         if unit in {"y", "q", "mo", "d", "ns"}:
             msg = f"Offsetting by {unit} is not yet supported for ibis."
diff --git a/narwhals/_polars/dataframe.py b/narwhals/_polars/dataframe.py
index 5a9fbbe670..328f99779e 100644
--- a/narwhals/_polars/dataframe.py
+++ b/narwhals/_polars/dataframe.py
@@ -181,7 +181,7 @@ def schema(self) -> dict[str, DType]:
 
     def join(
         self,
-        other: Self,
+        other: PolarsBaseFrame[NativePolarsFrame],
         *,
         how: JoinStrategy,
         left_on: Sequence[str] | None,
@@ -568,7 +568,7 @@ def to_polars(self) -> pl.DataFrame:
 
     def join(
         self,
-        other: Self,
+        other: PolarsBaseFrame[pl.DataFrame],
         *,
         how: JoinStrategy,
         left_on: Sequence[str] | None,
diff --git a/narwhals/_spark_like/dataframe.py b/narwhals/_spark_like/dataframe.py
index eba3001e7b..cd673ecec4 100644
--- a/narwhals/_spark_like/dataframe.py
+++ b/narwhals/_spark_like/dataframe.py
@@ -385,6 +385,7 @@ def unique(
     def join(
         self,
         other: Self,
+        *,
         how: JoinStrategy,
         left_on: Sequence[str] | None,
         right_on: Sequence[str] | None,
diff --git a/narwhals/_spark_like/expr.py b/narwhals/_spark_like/expr.py
index 3b5d1c1653..13dd167fe5 100644
--- a/narwhals/_spark_like/expr.py
+++ b/narwhals/_spark_like/expr.py
@@ -264,7 +264,7 @@ def _null_count(expr: Column) -> Column:
 
         return self._with_callable(_null_count)
 
-    def std(self, ddof: int) -> Self:
+    def std(self, *, ddof: int) -> Self:
         F = self._F
         if ddof == 0:
             return self._with_callable(F.stddev_pop)
@@ -277,7 +277,7 @@ def func(expr: Column) -> Column:
 
         return self._with_callable(func)
 
-    def var(self, ddof: int) -> Self:
+    def var(self, *, ddof: int) -> Self:
         F = self._F
         if ddof == 0:
             return self._with_callable(F.var_pop)
@@ -305,9 +305,9 @@ def _is_finite(expr: Column) -> Column:
 
         return self._with_elementwise(_is_finite)
 
-    def is_in(self, values: Sequence[Any]) -> Self:
+    def is_in(self, other: Sequence[Any]) -> Self:
         def _is_in(expr: Column) -> Column:
-            return expr.isin(values) if values else self._F.lit(False)
+            return expr.isin(other) if other else self._F.lit(False)
 
         return self._with_elementwise(_is_in)
 
diff --git a/narwhals/_sql/expr.py b/narwhals/_sql/expr.py
index db6c5dff9d..da062bfb2d 100644
--- a/narwhals/_sql/expr.py
+++ b/narwhals/_sql/expr.py
@@ -784,18 +784,9 @@ def str(self) -> SQLExprStringNamespace[Self]: ...
     def dt(self) -> SQLExprDateTimeNamesSpace[Self]: ...
 
     # Not implemented
-
-    arg_max: not_implemented = not_implemented()
-    arg_min: not_implemented = not_implemented()
-    arg_true: not_implemented = not_implemented()
-    cat: not_implemented = not_implemented()  # type: ignore[assignment]
-    drop_nulls: not_implemented = not_implemented()
-    ewm_mean: not_implemented = not_implemented()
-    gather_every: not_implemented = not_implemented()
-    head: not_implemented = not_implemented()
-    map_batches: not_implemented = not_implemented()
-    replace_strict: not_implemented = not_implemented()
-    sort: not_implemented = not_implemented()
-    tail: not_implemented = not_implemented()
-    sample: not_implemented = not_implemented()
-    unique: not_implemented = not_implemented()
+    cat: Any = not_implemented()
+    drop_nulls: Any = not_implemented()
+    ewm_mean: Any = not_implemented()
+    map_batches: Any = not_implemented()
+    replace_strict: Any = not_implemented()
+    unique: Any = not_implemented()
diff --git a/narwhals/dataframe.py b/narwhals/dataframe.py
index d5015d5a69..9cc5382c78 100644
--- a/narwhals/dataframe.py
+++ b/narwhals/dataframe.py
@@ -284,7 +284,7 @@ def top_k(
 
     def join(
         self,
-        other: Self,
+        other: BaseFrame[_FrameT],
         on: str | list[str] | None,
         how: JoinStrategy,
         *,
@@ -335,7 +335,7 @@ def gather_every(self, n: int, offset: int = 0) -> Self:
 
     def join_asof(
         self,
-        other: Self,
+        other: BaseFrame[_FrameT],
         *,
         left_on: str | None,
         right_on: str | None,
@@ -1111,7 +1111,7 @@ def to_dict(self, *, as_series: Literal[True] = ...) -> dict[str, Series[Any]]:
     def to_dict(self, *, as_series: Literal[False]) -> dict[str, list[Any]]: ...
     @overload
     def to_dict(
-        self, *, as_series: bool
+        self, *, as_series: bool = True
     ) -> dict[str, Series[Any]] | dict[str, list[Any]]: ...
     def to_dict(
         self, *, as_series: bool = True
@@ -1800,7 +1800,7 @@ def top_k(
 
     def join(
         self,
-        other: Self,
+        other: BaseFrame[DataFrameT],
         on: str | list[str] | None = None,
         how: JoinStrategy = "inner",
         *,
@@ -1846,7 +1846,7 @@ def join(
 
     def join_asof(
         self,
-        other: Self,
+        other: BaseFrame[DataFrameT],
         *,
         left_on: str | None = None,
         right_on: str | None = None,
@@ -3052,7 +3052,7 @@ def top_k(
 
     def join(
         self,
-        other: Self,
+        other: BaseFrame[LazyFrameT],
         on: str | list[str] | None = None,
         how: JoinStrategy = "inner",
         *,
@@ -3107,7 +3107,7 @@ def join(
 
     def join_asof(
         self,
-        other: Self,
+        other: BaseFrame[LazyFrameT],
         *,
         left_on: str | None = None,
         right_on: str | None = None,
diff --git a/narwhals/stable/v1/__init__.py b/narwhals/stable/v1/__init__.py
index 923a387288..f9780fa4a9 100644
--- a/narwhals/stable/v1/__init__.py
+++ b/narwhals/stable/v1/__init__.py
@@ -203,9 +203,9 @@ def to_dict(self, *, as_series: Literal[True] = ...) -> dict[str, Series[Any]]:
     def to_dict(self, *, as_series: Literal[False]) -> dict[str, list[Any]]: ...
     @overload
     def to_dict(
-        self, *, as_series: bool
+        self, *, as_series: bool = True
     ) -> dict[str, Series[Any]] | dict[str, list[Any]]: ...
-    def to_dict(
+    def to_dict(  # pyright: ignore[reportIncompatibleMethodOverride]
         self, *, as_series: bool = True
     ) -> dict[str, Series[Any]] | dict[str, list[Any]]:
         # Type checkers complain that `nw.Series` is not assignable to `nw.v1.stable.Series`.
diff --git a/narwhals/stable/v2/__init__.py b/narwhals/stable/v2/__init__.py
index e1963a4480..ada1ff20e8 100644
--- a/narwhals/stable/v2/__init__.py
+++ b/narwhals/stable/v2/__init__.py
@@ -198,9 +198,9 @@ def to_dict(self, *, as_series: Literal[True] = ...) -> dict[str, Series[Any]]:
     def to_dict(self, *, as_series: Literal[False]) -> dict[str, list[Any]]: ...
     @overload
     def to_dict(
-        self, *, as_series: bool
+        self, *, as_series: bool = True
     ) -> dict[str, Series[Any]] | dict[str, list[Any]]: ...
-    def to_dict(
+    def to_dict(  # pyright: ignore[reportIncompatibleMethodOverride]
         self, *, as_series: bool = True
     ) -> dict[str, Series[Any]] | dict[str, list[Any]]:
         # Type checkers complain that `nw.Series` is not assignable to `nw.v2.stable.Series`.
diff --git a/pyproject.toml b/pyproject.toml
index 303e0a0bf4..3f72013ddf 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -350,6 +350,7 @@ pythonPlatform = "All"
 # NOTE (`pyarrow-stubs` do unsafe `TypeAlias` and `TypeVar` imports)
 # pythonVersion = "3.9"
 reportMissingTypeArgument = "error"
+reportIncompatibleMethodOverride = "error"
 reportMissingImports = "none"
 reportMissingModuleSource = "none"
 reportPrivateImportUsage = "none"

From 1a8e7d66c8bf29ad4eca084ab8ba3adf76cfa255 Mon Sep 17 00:00:00 2001
From: dangotbanned <125183946+dangotbanned@users.noreply.github.com>
Date: Sun, 7 Sep 2025 13:40:24 +0000
Subject: [PATCH 2/6] chore(suggestion): Try turning ibis issue into a
 positive?

Part 1 of (https://github.com/narwhals-dev/narwhals/pull/3096#issuecomment-3263684697)

Isolates the problematic typing and then reuses it in other places it causes issues
---
 narwhals/_ibis/dataframe.py | 26 +++++--------------
 narwhals/_ibis/expr.py      | 52 +++++++++++++++++++++----------------
 narwhals/_ibis/utils.py     | 23 ++++++++++++++--
 3 files changed, 57 insertions(+), 44 deletions(-)

diff --git a/narwhals/_ibis/dataframe.py b/narwhals/_ibis/dataframe.py
index e976d54729..455c3ab4ba 100644
--- a/narwhals/_ibis/dataframe.py
+++ b/narwhals/_ibis/dataframe.py
@@ -336,29 +336,17 @@ def unique(
         return self._with_native(self.native.distinct(on=subset))
 
     def sort(self, *by: str, descending: bool | Sequence[bool], nulls_last: bool) -> Self:
-        if isinstance(descending, bool):
-            descending = [descending for _ in range(len(by))]
+        from narwhals._ibis.expr import IbisExpr
 
-        sort_cols: list[Any] = []
-
-        for i in range(len(by)):
-            direction_fn = ibis.desc if descending[i] else ibis.asc
-            col = direction_fn(by[i], nulls_first=not nulls_last)
-            sort_cols.append(col)
-
-        return self._with_native(self.native.order_by(*sort_cols))
+        cols = IbisExpr._sort(*by, descending=descending, nulls_last=nulls_last)
+        return self._with_native(self.native.order_by(*cols))
 
     def top_k(self, k: int, *, by: Iterable[str], reverse: bool | Sequence[bool]) -> Self:
-        if isinstance(reverse, bool):
-            reverse = [reverse] * len(list(by))
-        sort_cols = []
-
-        for is_reverse, by_col in zip_strict(reverse, by):
-            direction_fn = ibis.asc if is_reverse else ibis.desc
-            col = direction_fn(by_col, nulls_first=False)
-            sort_cols.append(cast("ir.Column", col))
+        from narwhals._ibis.expr import IbisExpr
 
-        return self._with_native(self.native.order_by(*sort_cols).head(k))
+        desc = not reverse if isinstance(reverse, bool) else [not el for el in reverse]
+        cols = IbisExpr._sort(*by, descending=desc, nulls_last=True)
+        return self._with_native(self.native.order_by(*cols).head(k))
 
     def drop_nulls(self, subset: Sequence[str] | None) -> Self:
         subset_ = subset if subset is not None else self.columns
diff --git a/narwhals/_ibis/expr.py b/narwhals/_ibis/expr.py
index 90d8f42482..3471d3c831 100644
--- a/narwhals/_ibis/expr.py
+++ b/narwhals/_ibis/expr.py
@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import operator
-from functools import partial
 from typing import TYPE_CHECKING, Any, Callable, Literal, TypeVar, cast
 
 import ibis
@@ -10,7 +9,17 @@
 from narwhals._ibis.expr_list import IbisExprListNamespace
 from narwhals._ibis.expr_str import IbisExprStringNamespace
 from narwhals._ibis.expr_struct import IbisExprStructNamespace
-from narwhals._ibis.utils import is_floating, lit, narwhals_to_native_dtype
+from narwhals._ibis.utils import (
+    IntoColumn,
+    asc_nulls_first,
+    asc_nulls_last,
+    desc_nulls_first,
+    desc_nulls_last,
+    extend_bool,
+    is_floating,
+    lit,
+    narwhals_to_native_dtype,
+)
 from narwhals._sql.expr import SQLExpr
 from narwhals._utils import Implementation, Version, not_implemented, zip_strict
 
@@ -79,7 +88,7 @@ def _window_expression(
         self,
         expr: ir.Value,
         partition_by: Sequence[str | ir.Value] = (),
-        order_by: Sequence[str | ir.Value] = (),
+        order_by: Sequence[IntoColumn] = (),
         rows_start: int | None = None,
         rows_end: int | None = None,
         *,
@@ -94,13 +103,11 @@ def _window_expression(
             rows_between = {"preceding": -rows_start}
         else:
             rows_between = {}
+        desc = descending or False
+        last = nulls_last or False
         window = ibis.window(
             group_by=partition_by,
-            order_by=self._sort(
-                *cast("Sequence[ir.Column]", order_by),
-                descending=descending,
-                nulls_last=nulls_last,
-            ),
+            order_by=self._sort(*order_by, descending=desc, nulls_last=last),
             **rows_between,
         )
         return expr.over(window)
@@ -114,24 +121,23 @@ def broadcast(self, kind: Literal[ExprKind.AGGREGATION, ExprKind.LITERAL]) -> Se
         # Ibis does its own broadcasting.
         return self
 
+    @staticmethod
     def _sort(
-        self,
-        *cols: ir.Column | str,
-        descending: Sequence[bool] | None = None,
-        nulls_last: Sequence[bool] | None = None,
+        *cols: IntoColumn,
+        descending: Sequence[bool] | bool = False,
+        nulls_last: Sequence[bool] | bool = False,
     ) -> Iterator[ir.Column]:
-        descending = descending or [False] * len(cols)
-        nulls_last = nulls_last or [False] * len(cols)
+        n = len(cols)
+        descending = extend_bool(descending, n)
+        nulls_last = extend_bool(nulls_last, n)
         mapping = {
-            (False, False): partial(ibis.asc, nulls_first=True),
-            (False, True): partial(ibis.asc, nulls_first=False),
-            (True, False): partial(ibis.desc, nulls_first=True),
-            (True, True): partial(ibis.desc, nulls_first=False),
+            (False, False): asc_nulls_first,
+            (False, True): asc_nulls_last,
+            (True, False): desc_nulls_first,
+            (True, True): desc_nulls_last,
         }
-        yield from (
-            cast("ir.Column", mapping[(_desc, _nulls_last)](col))
-            for col, _desc, _nulls_last in zip_strict(cols, descending, nulls_last)
-        )
+        for col, _desc, _nulls_last in zip_strict(cols, descending, nulls_last):
+            yield mapping[(_desc, _nulls_last)](col)
 
     @classmethod
     def from_column_names(
@@ -293,7 +299,7 @@ def is_unique(self) -> Self:
 
     def rank(self, method: RankMethod, *, descending: bool) -> Self:
         def _rank(expr: ir.Column) -> ir.Value:
-            order_by = next(self._sort(expr, descending=[descending], nulls_last=[True]))
+            order_by = next(self._sort(expr, descending=descending, nulls_last=True))
             window = ibis.window(order_by=order_by)
 
             if method == "dense":
diff --git a/narwhals/_ibis/utils.py b/narwhals/_ibis/utils.py
index a8b5bfa833..3aa84c776c 100644
--- a/narwhals/_ibis/utils.py
+++ b/narwhals/_ibis/utils.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from functools import lru_cache
+from functools import lru_cache, partial
 from typing import TYPE_CHECKING, Any, Literal, cast, overload
 
 import ibis
@@ -9,7 +9,7 @@
 from narwhals._utils import Version, isinstance_or_issubclass
 
 if TYPE_CHECKING:
-    from collections.abc import Mapping
+    from collections.abc import Callable, Iterable, Mapping, Sequence
     from datetime import timedelta
 
     import ibis.expr.types as ir
@@ -23,6 +23,8 @@
     from narwhals.dtypes import DType
     from narwhals.typing import IntoDType, PythonLiteral
 
+IntoColumn: TypeAlias = "str | ir.Value | ir.Column"
+SortFn: TypeAlias = "Callable[[IntoColumn], ir.Column]"
 Incomplete: TypeAlias = Any
 """Marker for upstream issues."""
 
@@ -45,6 +47,23 @@ def lit(value: Any, dtype: Any | None = None) -> Incomplete:
     return literal(value, dtype)
 
 
+asc_nulls_first = cast("SortFn", partial(ibis.asc, nulls_first=True))
+asc_nulls_last = cast("SortFn", partial(ibis.asc, nulls_first=False))
+desc_nulls_first = cast("SortFn", partial(ibis.desc, nulls_first=True))
+desc_nulls_last = cast("SortFn", partial(ibis.desc, nulls_first=False))
+
+
+def extend_bool(
+    value: bool | Iterable[bool],  # noqa: FBT001
+    n_match: int,
+) -> Sequence[bool]:
+    """Ensure the given bool or sequence of bools is the correct length.
+
+    Stolen from https://github.com/pola-rs/polars/blob/b8bfb07a4a37a8d449d6d1841e345817431142df/py-polars/polars/_utils/various.py#L580-L594
+    """
+    return [value] * n_match if isinstance(value, bool) else list(value)
+
+
 BucketUnit: TypeAlias = Literal[
     "years",
     "quarters",

From 9cda7ba6c5eec6e947a5e73fd42beadb588e6861 Mon Sep 17 00:00:00 2001
From: dangotbanned <125183946+dangotbanned@users.noreply.github.com>
Date: Sun, 7 Sep 2025 14:29:43 +0000
Subject: [PATCH 3/6] chore(typing): Ignore with context

Seems to appear at random and vanish

Error message is nonsense
---
 narwhals/_compliant/expr.py | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/narwhals/_compliant/expr.py b/narwhals/_compliant/expr.py
index f224ef82e9..159892117d 100644
--- a/narwhals/_compliant/expr.py
+++ b/narwhals/_compliant/expr.py
@@ -168,8 +168,14 @@ class DepthTrackingExpr(
     _depth: int
     _function_name: str
 
+    # NOTE: pyright bug?
+    # Method "from_column_names" overrides class "CompliantExpr" in an incompatible manner
+    # Parameter 2 type mismatch: base parameter is type "EvalNames[CompliantFrameT@DepthTrackingExpr]", override parameter is type "EvalNames[CompliantFrameT@DepthTrackingExpr]"
+    #   Type "EvalNames[CompliantFrameT@DepthTrackingExpr]" is not assignable to type "EvalNames[CompliantFrameT@DepthTrackingExpr]"
+    #     Parameter 1: type "CompliantFrameT@DepthTrackingExpr" is incompatible with type "CompliantFrameT@DepthTrackingExpr"
+    #       Type "CompliantFrameT@DepthTrackingExpr" is not assignable to type "CompliantFrameT@DepthTrackingExpr"
     @classmethod
-    def from_column_names(
+    def from_column_names(  # pyright: ignore[reportIncompatibleMethodOverride]
         cls: type[Self],
         evaluate_column_names: EvalNames[CompliantFrameT],
         /,

From 2174359c10c045b2deee8d69b38777c8c47db25b Mon Sep 17 00:00:00 2001
From: dangotbanned <125183946+dangotbanned@users.noreply.github.com>
Date: Sun, 7 Sep 2025 14:40:45 +0000
Subject: [PATCH 4/6] refactor: Move common `not_implemented` up

---
 narwhals/_compliant/expr.py | 13 ++++++++++++-
 narwhals/_dask/expr.py      |  4 ----
 narwhals/_sql/expr.py       |  4 ----
 3 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/narwhals/_compliant/expr.py b/narwhals/_compliant/expr.py
index 159892117d..310209cd21 100644
--- a/narwhals/_compliant/expr.py
+++ b/narwhals/_compliant/expr.py
@@ -28,7 +28,12 @@
     LazyExprT,
     NativeExprT,
 )
-from narwhals._utils import _StoresCompliant, qualified_type_name, zip_strict
+from narwhals._utils import (
+    _StoresCompliant,
+    not_implemented,
+    qualified_type_name,
+    zip_strict,
+)
 from narwhals.dependencies import is_numpy_array, is_numpy_scalar
 
 if TYPE_CHECKING:
@@ -905,6 +910,12 @@ def fn(names: Sequence[str]) -> Sequence[str]:
     def name(self) -> LazyExprNameNamespace[Self]:
         return LazyExprNameNamespace(self)
 
+    ewm_mean: not_implemented = not_implemented()  # pyright: ignore[reportIncompatibleMethodOverride]
+    map_batches: not_implemented = not_implemented()  # pyright: ignore[reportIncompatibleMethodOverride]
+    replace_strict: not_implemented = not_implemented()  # pyright: ignore[reportIncompatibleMethodOverride]
+
+    cat: not_implemented = not_implemented()  # type: ignore[assignment]
+
 
 class _ExprNamespace(  # type: ignore[misc]
     _StoresCompliant[CompliantExprT_co], Protocol[CompliantExprT_co]
diff --git a/narwhals/_dask/expr.py b/narwhals/_dask/expr.py
index daf097ae1a..db636bb504 100644
--- a/narwhals/_dask/expr.py
+++ b/narwhals/_dask/expr.py
@@ -682,12 +682,8 @@ def str(self) -> DaskExprStringNamespace:
     def dt(self) -> DaskExprDateTimeNamespace:
         return DaskExprDateTimeNamespace(self)
 
-    ewm_mean = not_implemented()
-    map_batches = not_implemented()
     rank = not_implemented()
-    replace_strict = not_implemented()
 
     # namespaces
     list: not_implemented = not_implemented()  # type: ignore[assignment]
-    cat: not_implemented = not_implemented()  # type: ignore[assignment]
     struct: not_implemented = not_implemented()  # type: ignore[assignment]
diff --git a/narwhals/_sql/expr.py b/narwhals/_sql/expr.py
index da062bfb2d..0e8115f1a4 100644
--- a/narwhals/_sql/expr.py
+++ b/narwhals/_sql/expr.py
@@ -784,9 +784,5 @@ def str(self) -> SQLExprStringNamespace[Self]: ...
     def dt(self) -> SQLExprDateTimeNamesSpace[Self]: ...
 
     # Not implemented
-    cat: Any = not_implemented()
     drop_nulls: Any = not_implemented()
-    ewm_mean: Any = not_implemented()
-    map_batches: Any = not_implemented()
-    replace_strict: Any = not_implemented()
     unique: Any = not_implemented()

From dc4a596f8fbfb685b8a55b3c0b96db2fc375e49d Mon Sep 17 00:00:00 2001
From: dangotbanned <125183946+dangotbanned@users.noreply.github.com>
Date: Sun, 7 Sep 2025 14:47:33 +0000
Subject: [PATCH 5/6] refactor(typing): Do this ignore instead actually

---
 narwhals/_compliant/expr.py | 6 +++---
 narwhals/_sql/expr.py       | 5 ++---
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/narwhals/_compliant/expr.py b/narwhals/_compliant/expr.py
index 310209cd21..55ed2d3e47 100644
--- a/narwhals/_compliant/expr.py
+++ b/narwhals/_compliant/expr.py
@@ -910,9 +910,9 @@ def fn(names: Sequence[str]) -> Sequence[str]:
     def name(self) -> LazyExprNameNamespace[Self]:
         return LazyExprNameNamespace(self)
 
-    ewm_mean: not_implemented = not_implemented()  # pyright: ignore[reportIncompatibleMethodOverride]
-    map_batches: not_implemented = not_implemented()  # pyright: ignore[reportIncompatibleMethodOverride]
-    replace_strict: not_implemented = not_implemented()  # pyright: ignore[reportIncompatibleMethodOverride]
+    ewm_mean = not_implemented()  # type: ignore[misc]
+    map_batches = not_implemented()  # type: ignore[misc]
+    replace_strict = not_implemented()  # type: ignore[misc]
 
     cat: not_implemented = not_implemented()  # type: ignore[assignment]
 
diff --git a/narwhals/_sql/expr.py b/narwhals/_sql/expr.py
index 0e8115f1a4..f427b73f40 100644
--- a/narwhals/_sql/expr.py
+++ b/narwhals/_sql/expr.py
@@ -783,6 +783,5 @@ def str(self) -> SQLExprStringNamespace[Self]: ...
     @property
     def dt(self) -> SQLExprDateTimeNamesSpace[Self]: ...
 
-    # Not implemented
-    drop_nulls: Any = not_implemented()
-    unique: Any = not_implemented()
+    drop_nulls = not_implemented()  # type: ignore[misc]
+    unique = not_implemented()  # type: ignore[misc]

From bc5934027d3e250e76bdbfd5d02c99433dbc6f6b Mon Sep 17 00:00:00 2001
From: dangotbanned <125183946+dangotbanned@users.noreply.github.com>
Date: Sun, 7 Sep 2025 14:57:40 +0000
Subject: [PATCH 6/6] be reasonable

https://github.com/narwhals-dev/narwhals/pull/3096#discussion_r2328699978
---
 narwhals/dataframe.py | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/narwhals/dataframe.py b/narwhals/dataframe.py
index 9cc5382c78..5b2752e029 100644
--- a/narwhals/dataframe.py
+++ b/narwhals/dataframe.py
@@ -91,6 +91,7 @@
     )
 
     PS = ParamSpec("PS")
+    Incomplete: TypeAlias = Any
 
 _FrameT = TypeVar("_FrameT", bound="IntoFrame")
 LazyFrameT = TypeVar("LazyFrameT", bound="IntoLazyFrame")
@@ -284,7 +285,7 @@ def top_k(
 
     def join(
         self,
-        other: BaseFrame[_FrameT],
+        other: Incomplete,
         on: str | list[str] | None,
         how: JoinStrategy,
         *,
@@ -335,7 +336,7 @@ def gather_every(self, n: int, offset: int = 0) -> Self:
 
     def join_asof(
         self,
-        other: BaseFrame[_FrameT],
+        other: Incomplete,
         *,
         left_on: str | None,
         right_on: str | None,
@@ -1800,7 +1801,7 @@ def top_k(
 
     def join(
         self,
-        other: BaseFrame[DataFrameT],
+        other: Self,
         on: str | list[str] | None = None,
         how: JoinStrategy = "inner",
         *,
@@ -1846,7 +1847,7 @@ def join(
 
     def join_asof(
         self,
-        other: BaseFrame[DataFrameT],
+        other: Self,
         *,
         left_on: str | None = None,
         right_on: str | None = None,
@@ -3052,7 +3053,7 @@ def top_k(
 
     def join(
         self,
-        other: BaseFrame[LazyFrameT],
+        other: Self,
         on: str | list[str] | None = None,
         how: JoinStrategy = "inner",
         *,
@@ -3107,7 +3108,7 @@ def join(
 
     def join_asof(
         self,
-        other: BaseFrame[LazyFrameT],
+        other: Self,
         *,
         left_on: str | None = None,
         right_on: str | None = None,