From d708aebac07af161dae527388267edcae1457369 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 10 Jun 2025 18:35:19 +0100
Subject: [PATCH 01/14] refactor if-when-else

---
 narwhals/_arrow/namespace.py       | 25 +++++++++++++++++--------
 narwhals/_compliant/when_then.py   |  7 ++++---
 narwhals/_pandas_like/namespace.py | 14 ++++++++++----
 3 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/narwhals/_arrow/namespace.py b/narwhals/_arrow/namespace.py
index 2730ebaae9..b036f79ba9 100644
--- a/narwhals/_arrow/namespace.py
+++ b/narwhals/_arrow/namespace.py
@@ -24,7 +24,7 @@
 from narwhals._utils import Implementation
 
 if TYPE_CHECKING:
-    from narwhals._arrow.typing import ArrayOrScalar, ChunkedArrayAny, Incomplete
+    from narwhals._arrow.typing import ChunkedArrayAny, Incomplete
     from narwhals._utils import Version
     from narwhals.dtypes import DType
     from narwhals.typing import NonNestedLiteral
@@ -272,14 +272,23 @@ def _then(self) -> type[ArrowThen]:
         return ArrowThen
 
     def _if_then_else(
-        self,
-        when: ChunkedArrayAny,
-        then: ChunkedArrayAny,
-        otherwise: ArrayOrScalar | NonNestedLiteral,
-        /,
+        self, when: ArrowSeries, then: ArrowSeries, otherwise: ArrowSeries | None, /
     ) -> ChunkedArrayAny:
-        otherwise = pa.nulls(len(when), then.type) if otherwise is None else otherwise
-        return pc.if_else(when, then, otherwise)
+        from narwhals._arrow.utils import align_series_full_broadcast
+
+        if otherwise is not None:
+            _when, _then, _otherwise = align_series_full_broadcast(when, then, otherwise)
+            _when = _when.native
+            _then = _then.native
+            _otherwise = _otherwise.native
+        else:
+            _when, _then = align_series_full_broadcast(when, then)
+            _when = _when.native
+            _then = _then.native
+            otherwise = (
+                pa.nulls(len(when), _then.native.type) if otherwise is None else otherwise
+            )
+        return pc.if_else(_when, _then, _otherwise)
 
 
 class ArrowThen(CompliantThen[ArrowDataFrame, ArrowSeries, ArrowExpr], ArrowExpr): ...
diff --git a/narwhals/_compliant/when_then.py b/narwhals/_compliant/when_then.py
index 37e70dcb55..99e350d122 100644
--- a/narwhals/_compliant/when_then.py
+++ b/narwhals/_compliant/when_then.py
@@ -165,10 +165,11 @@ def __call__(self, df: EagerDataFrameT, /) -> Sequence[EagerSeriesT]:
             then = when.alias("literal")._from_scalar(self._then_value)
             then._broadcast = True
         if is_expr(self._otherwise_value):
-            otherwise = df._extract_comparand(self._otherwise_value(df)[0])
+            otherwise = self._otherwise_value(df)[0]
         else:
-            otherwise = self._otherwise_value
-        result = self._if_then_else(when.native, df._extract_comparand(then), otherwise)
+            otherwise = when._from_scalar(self._otherwise_value)
+            otherwise._broadcast = True
+        result = self._if_then_else(when, then, otherwise)
         return [then._with_native(result)]
 
 
diff --git a/narwhals/_pandas_like/namespace.py b/narwhals/_pandas_like/namespace.py
index bbff8bbc7e..ee4bfc0379 100644
--- a/narwhals/_pandas_like/namespace.py
+++ b/narwhals/_pandas_like/namespace.py
@@ -324,12 +324,18 @@ def _then(self) -> type[PandasThen]:
 
     def _if_then_else(
         self,
-        when: pd.Series[Any],
-        then: pd.Series[Any],
-        otherwise: pd.Series[Any] | NonNestedLiteral,
+        when: PandasLikeSeries,
+        then: PandasLikeSeries,
+        otherwise: PandasLikeSeries | None,
         /,
     ) -> pd.Series[Any]:
-        return then.where(when) if otherwise is None else then.where(when, otherwise)
+        from narwhals._pandas_like.utils import align_series_full_broadcast
+
+        if otherwise is None:
+            when, then = align_series_full_broadcast(when, then)
+            return then.native.where(when.native)
+        when, then, otherwise = align_series_full_broadcast(when, then, otherwise)
+        return then.native.where(when.native, otherwise.native)
 
 
 class PandasThen(

From 8dfc79aeab495953bd6d0918d3ced0e3b42a7aa7 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 10 Jun 2025 18:36:17 +0100
Subject: [PATCH 02/14] refactor if-when-else

---
 narwhals/_arrow/namespace.py       | 2 --
 narwhals/_pandas_like/namespace.py | 2 --
 2 files changed, 4 deletions(-)

diff --git a/narwhals/_arrow/namespace.py b/narwhals/_arrow/namespace.py
index b036f79ba9..8375ba3863 100644
--- a/narwhals/_arrow/namespace.py
+++ b/narwhals/_arrow/namespace.py
@@ -274,8 +274,6 @@ def _then(self) -> type[ArrowThen]:
     def _if_then_else(
         self, when: ArrowSeries, then: ArrowSeries, otherwise: ArrowSeries | None, /
     ) -> ChunkedArrayAny:
-        from narwhals._arrow.utils import align_series_full_broadcast
-
         if otherwise is not None:
             _when, _then, _otherwise = align_series_full_broadcast(when, then, otherwise)
             _when = _when.native
diff --git a/narwhals/_pandas_like/namespace.py b/narwhals/_pandas_like/namespace.py
index ee4bfc0379..c9fe1a58c2 100644
--- a/narwhals/_pandas_like/namespace.py
+++ b/narwhals/_pandas_like/namespace.py
@@ -329,8 +329,6 @@ def _if_then_else(
         otherwise: PandasLikeSeries | None,
         /,
     ) -> pd.Series[Any]:
-        from narwhals._pandas_like.utils import align_series_full_broadcast
-
         if otherwise is None:
             when, then = align_series_full_broadcast(when, then)
             return then.native.where(when.native)

From bad8fed45766b350eb20389df51cd96f2ea0ff13 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 10 Jun 2025 18:38:11 +0100
Subject: [PATCH 03/14] refactor if-when-else

---
 narwhals/_arrow/namespace.py | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/narwhals/_arrow/namespace.py b/narwhals/_arrow/namespace.py
index 8375ba3863..bf5920f7be 100644
--- a/narwhals/_arrow/namespace.py
+++ b/narwhals/_arrow/namespace.py
@@ -274,19 +274,13 @@ def _then(self) -> type[ArrowThen]:
     def _if_then_else(
         self, when: ArrowSeries, then: ArrowSeries, otherwise: ArrowSeries | None, /
     ) -> ChunkedArrayAny:
-        if otherwise is not None:
-            _when, _then, _otherwise = align_series_full_broadcast(when, then, otherwise)
-            _when = _when.native
-            _then = _then.native
-            _otherwise = _otherwise.native
-        else:
-            _when, _then = align_series_full_broadcast(when, then)
-            _when = _when.native
-            _then = _then.native
-            otherwise = (
-                pa.nulls(len(when), _then.native.type) if otherwise is None else otherwise
+        if otherwise is None:
+            when, then = align_series_full_broadcast(when, then)
+            return pc.if_else(
+                when.native, then.native, pa.nulls(len(when.native), then.native.type)
             )
-        return pc.if_else(_when, _then, _otherwise)
+        when, then, otherwise = align_series_full_broadcast(when, then, otherwise)
+        return pc.if_else(when.native, then.native, otherwise.native)
 
 
 class ArrowThen(CompliantThen[ArrowDataFrame, ArrowSeries, ArrowExpr], ArrowExpr): ...

From 29d625860570a16ee792cc21e727317446084ae8 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 10 Jun 2025 18:53:05 +0100
Subject: [PATCH 04/14] try fixup

---
 narwhals/_compliant/when_then.py | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/narwhals/_compliant/when_then.py b/narwhals/_compliant/when_then.py
index 99e350d122..7fcc3d9c2a 100644
--- a/narwhals/_compliant/when_then.py
+++ b/narwhals/_compliant/when_then.py
@@ -43,7 +43,7 @@
 class CompliantWhen(Protocol38[FrameT, SeriesT, ExprT]):
     _condition: ExprT
     _then_value: IntoExpr[SeriesT, ExprT]
-    _otherwise_value: IntoExpr[SeriesT, ExprT]
+    _otherwise_value: IntoExpr[SeriesT, ExprT] | None
     _implementation: Implementation
     _backend_version: tuple[int, ...]
     _version: Version
@@ -148,11 +148,7 @@ class EagerWhen(
     Protocol38[EagerDataFrameT, EagerSeriesT, EagerExprT, NativeSeriesT],
 ):
     def _if_then_else(
-        self,
-        when: NativeSeriesT,
-        then: NativeSeriesT,
-        otherwise: NativeSeriesT | NonNestedLiteral | Scalar,
-        /,
+        self, when: EagerSeriesT, then: EagerSeriesT, otherwise: EagerSeriesT | None, /
     ) -> NativeSeriesT: ...
 
     def __call__(self, df: EagerDataFrameT, /) -> Sequence[EagerSeriesT]:
@@ -166,9 +162,11 @@ def __call__(self, df: EagerDataFrameT, /) -> Sequence[EagerSeriesT]:
             then._broadcast = True
         if is_expr(self._otherwise_value):
             otherwise = self._otherwise_value(df)[0]
-        else:
+        elif self._otherwise_value is not None:
             otherwise = when._from_scalar(self._otherwise_value)
             otherwise._broadcast = True
+        else:
+            otherwise = self._otherwise_value
         result = self._if_then_else(when, then, otherwise)
         return [then._with_native(result)]
 

From aab3a7026a700e7f01ae1bb4e4049d1c219cb37f Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 10 Jun 2025 19:07:50 +0100
Subject: [PATCH 05/14] try fixup

---
 narwhals/_arrow/namespace.py       | 14 ++++++++------
 narwhals/_compliant/namespace.py   |  2 +-
 narwhals/_compliant/when_then.py   |  8 +++-----
 narwhals/_pandas_like/namespace.py | 16 ++++++++--------
 4 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/narwhals/_arrow/namespace.py b/narwhals/_arrow/namespace.py
index bf5920f7be..c0138d2775 100644
--- a/narwhals/_arrow/namespace.py
+++ b/narwhals/_arrow/namespace.py
@@ -24,7 +24,7 @@
 from narwhals._utils import Implementation
 
 if TYPE_CHECKING:
-    from narwhals._arrow.typing import ChunkedArrayAny, Incomplete
+    from narwhals._arrow.typing import Incomplete
     from narwhals._utils import Version
     from narwhals.dtypes import DType
     from narwhals.typing import NonNestedLiteral
@@ -266,21 +266,23 @@ def func(df: ArrowDataFrame) -> list[ArrowSeries]:
         )
 
 
-class ArrowWhen(EagerWhen[ArrowDataFrame, ArrowSeries, ArrowExpr, "ChunkedArrayAny"]):
+class ArrowWhen(EagerWhen[ArrowDataFrame, ArrowSeries, ArrowExpr]):
     @property
     def _then(self) -> type[ArrowThen]:
         return ArrowThen
 
     def _if_then_else(
         self, when: ArrowSeries, then: ArrowSeries, otherwise: ArrowSeries | None, /
-    ) -> ChunkedArrayAny:
+    ) -> ArrowSeries:
         if otherwise is None:
             when, then = align_series_full_broadcast(when, then)
-            return pc.if_else(
+            res_native = pc.if_else(
                 when.native, then.native, pa.nulls(len(when.native), then.native.type)
             )
-        when, then, otherwise = align_series_full_broadcast(when, then, otherwise)
-        return pc.if_else(when.native, then.native, otherwise.native)
+        else:
+            when, then, otherwise = align_series_full_broadcast(when, then, otherwise)
+            res_native = pc.if_else(when.native, then.native, otherwise.native)
+        return then._with_native(res_native)
 
 
 class ArrowThen(CompliantThen[ArrowDataFrame, ArrowSeries, ArrowExpr], ArrowExpr): ...
diff --git a/narwhals/_compliant/namespace.py b/narwhals/_compliant/namespace.py
index d0440152a8..2a7188f741 100644
--- a/narwhals/_compliant/namespace.py
+++ b/narwhals/_compliant/namespace.py
@@ -140,7 +140,7 @@ def _dataframe(self) -> type[EagerDataFrameT]: ...
     def _series(self) -> type[EagerSeriesT]: ...
     def when(
         self, predicate: EagerExprT
-    ) -> EagerWhen[EagerDataFrameT, EagerSeriesT, EagerExprT, NativeSeriesT]: ...
+    ) -> EagerWhen[EagerDataFrameT, EagerSeriesT, EagerExprT]: ...
 
     @overload
     def from_native(self, data: NativeFrameT, /) -> EagerDataFrameT: ...
diff --git a/narwhals/_compliant/when_then.py b/narwhals/_compliant/when_then.py
index 7fcc3d9c2a..a2a2b4fe78 100644
--- a/narwhals/_compliant/when_then.py
+++ b/narwhals/_compliant/when_then.py
@@ -13,7 +13,6 @@
     EagerSeriesT,
     LazyExprAny,
     NativeExprT,
-    NativeSeriesT,
     WindowFunction,
 )
 from narwhals._typing_compat import Protocol38
@@ -145,11 +144,11 @@ def from_when(
 
 class EagerWhen(
     CompliantWhen[EagerDataFrameT, EagerSeriesT, EagerExprT],
-    Protocol38[EagerDataFrameT, EagerSeriesT, EagerExprT, NativeSeriesT],
+    Protocol38[EagerDataFrameT, EagerSeriesT, EagerExprT],
 ):
     def _if_then_else(
         self, when: EagerSeriesT, then: EagerSeriesT, otherwise: EagerSeriesT | None, /
-    ) -> NativeSeriesT: ...
+    ) -> EagerSeriesT: ...
 
     def __call__(self, df: EagerDataFrameT, /) -> Sequence[EagerSeriesT]:
         is_expr = self._condition._is_expr
@@ -167,8 +166,7 @@ def __call__(self, df: EagerDataFrameT, /) -> Sequence[EagerSeriesT]:
             otherwise._broadcast = True
         else:
             otherwise = self._otherwise_value
-        result = self._if_then_else(when, then, otherwise)
-        return [then._with_native(result)]
+        return [self._if_then_else(when, then, otherwise)]
 
 
 class LazyWhen(
diff --git a/narwhals/_pandas_like/namespace.py b/narwhals/_pandas_like/namespace.py
index c9fe1a58c2..bfcf14acb9 100644
--- a/narwhals/_pandas_like/namespace.py
+++ b/narwhals/_pandas_like/namespace.py
@@ -3,7 +3,7 @@
 import operator
 import warnings
 from functools import reduce
-from typing import TYPE_CHECKING, Any, Literal, Sequence
+from typing import TYPE_CHECKING, Literal, Sequence
 
 from narwhals._compliant import CompliantThen, EagerNamespace, EagerWhen
 from narwhals._expression_parsing import (
@@ -315,9 +315,7 @@ def func(df: PandasLikeDataFrame) -> list[PandasLikeSeries]:
         )
 
 
-class PandasWhen(
-    EagerWhen[PandasLikeDataFrame, PandasLikeSeries, PandasLikeExpr, "pd.Series[Any]"]
-):
+class PandasWhen(EagerWhen[PandasLikeDataFrame, PandasLikeSeries, PandasLikeExpr]):
     @property
     def _then(self) -> type[PandasThen]:
         return PandasThen
@@ -328,12 +326,14 @@ def _if_then_else(
         then: PandasLikeSeries,
         otherwise: PandasLikeSeries | None,
         /,
-    ) -> pd.Series[Any]:
+    ) -> PandasLikeSeries:
         if otherwise is None:
             when, then = align_series_full_broadcast(when, then)
-            return then.native.where(when.native)
-        when, then, otherwise = align_series_full_broadcast(when, then, otherwise)
-        return then.native.where(when.native, otherwise.native)
+            res_native = then.native.where(when.native)
+        else:
+            when, then, otherwise = align_series_full_broadcast(when, then, otherwise)
+            res_native = then.native.where(when.native, otherwise.native)
+        return then._with_native(res_native)
 
 
 class PandasThen(

From cdf57d9c2fc21e876309ef2b260645415a1feded Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 10 Jun 2025 19:15:05 +0100
Subject: [PATCH 06/14] chunkedarrayany import

---
 narwhals/_arrow/namespace.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/narwhals/_arrow/namespace.py b/narwhals/_arrow/namespace.py
index c0138d2775..2496a3d4c7 100644
--- a/narwhals/_arrow/namespace.py
+++ b/narwhals/_arrow/namespace.py
@@ -12,6 +12,7 @@
 from narwhals._arrow.expr import ArrowExpr
 from narwhals._arrow.selectors import ArrowSelectorNamespace
 from narwhals._arrow.series import ArrowSeries
+from narwhals._arrow.typing import ChunkedArrayAny
 from narwhals._arrow.utils import (
     align_series_full_broadcast,
     cast_to_comparable_string_types,
@@ -31,7 +32,7 @@
 
 
 class ArrowNamespace(
-    EagerNamespace[ArrowDataFrame, ArrowSeries, ArrowExpr, "pa.Table", "ChunkedArrayAny"]
+    EagerNamespace[ArrowDataFrame, ArrowSeries, ArrowExpr, pa.Table, ChunkedArrayAny]
 ):
     @property
     def _dataframe(self) -> type[ArrowDataFrame]:

From 3c7eb58ec846bd092cc1157b04d57a90941aa7df Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 10 Jun 2025 19:16:37 +0100
Subject: [PATCH 07/14] any import

---
 narwhals/_pandas_like/namespace.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/narwhals/_pandas_like/namespace.py b/narwhals/_pandas_like/namespace.py
index bfcf14acb9..d99fd99bfb 100644
--- a/narwhals/_pandas_like/namespace.py
+++ b/narwhals/_pandas_like/namespace.py
@@ -3,7 +3,9 @@
 import operator
 import warnings
 from functools import reduce
-from typing import TYPE_CHECKING, Literal, Sequence
+from typing import TYPE_CHECKING, Any, Literal, Sequence
+
+import pandas as pd
 
 from narwhals._compliant import CompliantThen, EagerNamespace, EagerWhen
 from narwhals._expression_parsing import (
@@ -17,8 +19,6 @@
 from narwhals._pandas_like.utils import align_series_full_broadcast
 
 if TYPE_CHECKING:
-    import pandas as pd
-
     from narwhals._pandas_like.typing import NDFrameT
     from narwhals._utils import Implementation, Version
     from narwhals.dtypes import DType
@@ -33,8 +33,8 @@ class PandasLikeNamespace(
         PandasLikeDataFrame,
         PandasLikeSeries,
         PandasLikeExpr,
-        "pd.DataFrame",
-        "pd.Series[Any]",
+        pd.DataFrame,
+        pd.Series[Any],
     ]
 ):
     @property

From c8b4f0a3ebb08a92fd312ac27813f48e651e88ba Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 10 Jun 2025 19:18:58 +0100
Subject: [PATCH 08/14] any import

---
 narwhals/_pandas_like/namespace.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/narwhals/_pandas_like/namespace.py b/narwhals/_pandas_like/namespace.py
index d99fd99bfb..cffa0b916b 100644
--- a/narwhals/_pandas_like/namespace.py
+++ b/narwhals/_pandas_like/namespace.py
@@ -3,7 +3,7 @@
 import operator
 import warnings
 from functools import reduce
-from typing import TYPE_CHECKING, Any, Literal, Sequence
+from typing import TYPE_CHECKING, Literal, Sequence
 
 import pandas as pd
 
@@ -34,7 +34,7 @@ class PandasLikeNamespace(
         PandasLikeSeries,
         PandasLikeExpr,
         pd.DataFrame,
-        pd.Series[Any],
+        "pd.Series[Any]",
     ]
 ):
     @property

From c4974f7ecb3aa08ae8873f02770d8bd299574471 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 10 Jun 2025 19:19:18 +0100
Subject: [PATCH 09/14] any import

---
 narwhals/_pandas_like/namespace.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/narwhals/_pandas_like/namespace.py b/narwhals/_pandas_like/namespace.py
index cffa0b916b..7d9df1e1ac 100644
--- a/narwhals/_pandas_like/namespace.py
+++ b/narwhals/_pandas_like/namespace.py
@@ -19,6 +19,8 @@
 from narwhals._pandas_like.utils import align_series_full_broadcast
 
 if TYPE_CHECKING:
+    from typing import Any  # noqa: F401
+
     from narwhals._pandas_like.typing import NDFrameT
     from narwhals._utils import Implementation, Version
     from narwhals.dtypes import DType

From 5a5f7a7915e217e6169ac33e62a7a648a4b9442f Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 10 Jun 2025 19:28:10 +0100
Subject: [PATCH 10/14] imports

---
 narwhals/_arrow/namespace.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/narwhals/_arrow/namespace.py b/narwhals/_arrow/namespace.py
index 2496a3d4c7..fe50764997 100644
--- a/narwhals/_arrow/namespace.py
+++ b/narwhals/_arrow/namespace.py
@@ -12,7 +12,6 @@
 from narwhals._arrow.expr import ArrowExpr
 from narwhals._arrow.selectors import ArrowSelectorNamespace
 from narwhals._arrow.series import ArrowSeries
-from narwhals._arrow.typing import ChunkedArrayAny
 from narwhals._arrow.utils import (
     align_series_full_broadcast,
     cast_to_comparable_string_types,
@@ -25,14 +24,17 @@
 from narwhals._utils import Implementation
 
 if TYPE_CHECKING:
-    from narwhals._arrow.typing import Incomplete
+    from narwhals._arrow.typing import (
+        ChunkedArrayAny,  # noqa: F401
+        Incomplete,
+    )
     from narwhals._utils import Version
     from narwhals.dtypes import DType
     from narwhals.typing import NonNestedLiteral
 
 
 class ArrowNamespace(
-    EagerNamespace[ArrowDataFrame, ArrowSeries, ArrowExpr, pa.Table, ChunkedArrayAny]
+    EagerNamespace[ArrowDataFrame, ArrowSeries, ArrowExpr, pa.Table, "ChunkedArrayAny"]
 ):
     @property
     def _dataframe(self) -> type[ArrowDataFrame]:

From 20793f57a5004cb2c022f478c1436647eb9b32fa Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 10 Jun 2025 23:22:41 +0100
Subject: [PATCH 11/14] just silence type checkers

---
 narwhals/_compliant/namespace.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/narwhals/_compliant/namespace.py b/narwhals/_compliant/namespace.py
index 2a7188f741..2d47baac31 100644
--- a/narwhals/_compliant/namespace.py
+++ b/narwhals/_compliant/namespace.py
@@ -130,7 +130,8 @@ def from_native(self, data: NativeFrameT_co | Any, /) -> CompliantLazyFrameT:
             raise TypeError(msg)
 
 
-class EagerNamespace(
+# Invariant type variable "NativeSeriesT" used in protocol where covariant one is expected
+class EagerNamespace(  # type: ignore[misc]
     DepthTrackingNamespace[EagerDataFrameT, EagerExprT],
     Protocol[EagerDataFrameT, EagerSeriesT, EagerExprT, NativeFrameT, NativeSeriesT],
 ):

From e19d5e17ce089ecea4944eae6e2753832bb8c730 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Wed, 11 Jun 2025 10:49:59 +0100
Subject: [PATCH 12/14] remove NativeSeriesT from EagerDataFrame /
 EagerNamespace

---
 narwhals/_arrow/dataframe.py       |  4 +---
 narwhals/_arrow/namespace.py       |  4 +---
 narwhals/_compliant/dataframe.py   | 15 +++++----------
 narwhals/_compliant/expr.py        |  2 +-
 narwhals/_compliant/namespace.py   | 22 +++-------------------
 narwhals/_compliant/series.py      |  4 +---
 narwhals/_compliant/typing.py      |  8 +++++---
 narwhals/_pandas_like/dataframe.py |  4 +---
 narwhals/_pandas_like/namespace.py |  8 +-------
 9 files changed, 19 insertions(+), 52 deletions(-)

diff --git a/narwhals/_arrow/dataframe.py b/narwhals/_arrow/dataframe.py
index aef16939ca..e2168baa28 100644
--- a/narwhals/_arrow/dataframe.py
+++ b/narwhals/_arrow/dataframe.py
@@ -83,9 +83,7 @@
     PromoteOptions: TypeAlias = Literal["none", "default", "permissive"]
 
 
-class ArrowDataFrame(
-    EagerDataFrame["ArrowSeries", "ArrowExpr", "pa.Table", "ChunkedArrayAny"]
-):
+class ArrowDataFrame(EagerDataFrame["ArrowSeries", "ArrowExpr", "pa.Table"]):
     def __init__(
         self,
         native_dataframe: pa.Table,
diff --git a/narwhals/_arrow/namespace.py b/narwhals/_arrow/namespace.py
index fe50764997..a032c11d7a 100644
--- a/narwhals/_arrow/namespace.py
+++ b/narwhals/_arrow/namespace.py
@@ -33,9 +33,7 @@
     from narwhals.typing import NonNestedLiteral
 
 
-class ArrowNamespace(
-    EagerNamespace[ArrowDataFrame, ArrowSeries, ArrowExpr, pa.Table, "ChunkedArrayAny"]
-):
+class ArrowNamespace(EagerNamespace[ArrowDataFrame, ArrowSeries, ArrowExpr, pa.Table]):
     @property
     def _dataframe(self) -> type[ArrowDataFrame]:
         return ArrowDataFrame
diff --git a/narwhals/_compliant/dataframe.py b/narwhals/_compliant/dataframe.py
index 57226ff5b4..5f210550e6 100644
--- a/narwhals/_compliant/dataframe.py
+++ b/narwhals/_compliant/dataframe.py
@@ -23,7 +23,6 @@
     EagerSeriesT,
     NativeExprT,
     NativeFrameT,
-    NativeSeriesT,
 )
 from narwhals._translate import (
     ArrowConvertible,
@@ -402,11 +401,11 @@ def _check_columns_exist(self, subset: Sequence[str]) -> ColumnNotFoundError | N
 class EagerDataFrame(
     CompliantDataFrame[EagerSeriesT, EagerExprT, NativeFrameT, "DataFrame[NativeFrameT]"],
     CompliantLazyFrame[EagerExprT, NativeFrameT, "DataFrame[NativeFrameT]"],
-    Protocol[EagerSeriesT, EagerExprT, NativeFrameT, NativeSeriesT],
+    Protocol[EagerSeriesT, EagerExprT, NativeFrameT],
 ):
     def __narwhals_namespace__(
         self,
-    ) -> EagerNamespace[Self, EagerSeriesT, EagerExprT, NativeFrameT, NativeSeriesT]: ...
+    ) -> EagerNamespace[Self, EagerSeriesT, EagerExprT, NativeFrameT]: ...
 
     def to_narwhals(self) -> DataFrame[NativeFrameT]:
         return self._version.dataframe(self, level="full")
@@ -450,14 +449,10 @@ def _numpy_column_names(
     ) -> list[str]:
         return list(columns or (f"column_{x}" for x in range(data.shape[1])))
 
-    def _gather(self, rows: SizedMultiIndexSelector[NativeSeriesT]) -> Self: ...
+    def _gather(self, rows: SizedMultiIndexSelector[Any]) -> Self: ...
     def _gather_slice(self, rows: _SliceIndex | range) -> Self: ...
-    def _select_multi_index(
-        self, columns: SizedMultiIndexSelector[NativeSeriesT]
-    ) -> Self: ...
-    def _select_multi_name(
-        self, columns: SizedMultiNameSelector[NativeSeriesT]
-    ) -> Self: ...
+    def _select_multi_index(self, columns: SizedMultiIndexSelector[Any]) -> Self: ...
+    def _select_multi_name(self, columns: SizedMultiNameSelector[Any]) -> Self: ...
     def _select_slice_index(self, columns: _SliceIndex | range) -> Self: ...
     def _select_slice_name(self, columns: _SliceName) -> Self: ...
     def __getitem__(  # noqa: C901, PLR0912
diff --git a/narwhals/_compliant/expr.py b/narwhals/_compliant/expr.py
index bb783398bf..9490bc8b89 100644
--- a/narwhals/_compliant/expr.py
+++ b/narwhals/_compliant/expr.py
@@ -337,7 +337,7 @@ def __call__(self, df: EagerDataFrameT) -> Sequence[EagerSeriesT]:
 
     def __narwhals_namespace__(
         self,
-    ) -> EagerNamespace[EagerDataFrameT, EagerSeriesT, Self, Any, Any]: ...
+    ) -> EagerNamespace[EagerDataFrameT, EagerSeriesT, Self, Any]: ...
     def __narwhals_expr__(self) -> None: ...
 
     @classmethod
diff --git a/narwhals/_compliant/namespace.py b/narwhals/_compliant/namespace.py
index 2d47baac31..7371232336 100644
--- a/narwhals/_compliant/namespace.py
+++ b/narwhals/_compliant/namespace.py
@@ -23,7 +23,6 @@
     LazyExprT,
     NativeFrameT,
     NativeFrameT_co,
-    NativeSeriesT,
 )
 from narwhals._utils import (
     exclude_column_names,
@@ -130,10 +129,9 @@ def from_native(self, data: NativeFrameT_co | Any, /) -> CompliantLazyFrameT:
             raise TypeError(msg)
 
 
-# Invariant type variable "NativeSeriesT" used in protocol where covariant one is expected
-class EagerNamespace(  # type: ignore[misc]
+class EagerNamespace(
     DepthTrackingNamespace[EagerDataFrameT, EagerExprT],
-    Protocol[EagerDataFrameT, EagerSeriesT, EagerExprT, NativeFrameT, NativeSeriesT],
+    Protocol[EagerDataFrameT, EagerSeriesT, EagerExprT, NativeFrameT],
 ):
     @property
     def _dataframe(self) -> type[EagerDataFrameT]: ...
@@ -143,21 +141,7 @@ def when(
         self, predicate: EagerExprT
     ) -> EagerWhen[EagerDataFrameT, EagerSeriesT, EagerExprT]: ...
 
-    @overload
-    def from_native(self, data: NativeFrameT, /) -> EagerDataFrameT: ...
-    @overload
-    def from_native(self, data: NativeSeriesT, /) -> EagerSeriesT: ...
-    # TODO @dangotbanned: Align `PandasLike` typing with `_namespace`, then drop this `@overload`
-    # - Using the guards there introduces `_NativeModin`, `_NativeCuDF`
-    # - These types haven't been integrated into the backend
-    # - Most of the `pandas` stuff is still untyped
-    @overload
-    def from_native(
-        self, data: NativeFrameT | NativeSeriesT | Any, /
-    ) -> EagerDataFrameT | EagerSeriesT: ...
-    def from_native(
-        self, data: NativeFrameT | NativeSeriesT | Any, /
-    ) -> EagerDataFrameT | EagerSeriesT:
+    def from_native(self, data: Any, /) -> EagerDataFrameT | EagerSeriesT:
         if self._dataframe._is_native(data):
             return self._dataframe.from_native(data, context=self)
         elif self._series._is_native(data):
diff --git a/narwhals/_compliant/series.py b/narwhals/_compliant/series.py
index cc194af4ca..fb0cb98ca7 100644
--- a/narwhals/_compliant/series.py
+++ b/narwhals/_compliant/series.py
@@ -300,9 +300,7 @@ def _with_native(
         """
         ...
 
-    def __narwhals_namespace__(
-        self,
-    ) -> EagerNamespace[Any, Self, Any, Any, NativeSeriesT]: ...
+    def __narwhals_namespace__(self) -> EagerNamespace[Any, Self, Any, Any]: ...
 
     def _to_expr(self) -> EagerExpr[Any, Any]:
         return self.__narwhals_namespace__()._expr._from_series(self)  # type: ignore[no-any-return]
diff --git a/narwhals/_compliant/typing.py b/narwhals/_compliant/typing.py
index 457d71d6b5..4c3685b728 100644
--- a/narwhals/_compliant/typing.py
+++ b/narwhals/_compliant/typing.py
@@ -60,10 +60,12 @@ class ScalarKwargs(TypedDict, total=False):
 
 DepthTrackingExprAny: TypeAlias = "DepthTrackingExpr[Any, Any]"
 
-EagerDataFrameAny: TypeAlias = "EagerDataFrame[Any, Any, Any, Any]"
+EagerDataFrameAny: TypeAlias = "EagerDataFrame[Any, Any, Any]"
 EagerSeriesAny: TypeAlias = "EagerSeries[Any]"
 EagerExprAny: TypeAlias = "EagerExpr[Any, Any]"
-EagerNamespaceAny: TypeAlias = "EagerNamespace[EagerDataFrameAny, EagerSeriesAny, EagerExprAny, NativeFrame, NativeSeries]"
+EagerNamespaceAny: TypeAlias = (
+    "EagerNamespace[EagerDataFrameAny, EagerSeriesAny, EagerExprAny, NativeFrame]"
+)
 
 LazyExprAny: TypeAlias = "LazyExpr[Any, Any]"
 
@@ -124,7 +126,7 @@ class ScalarKwargs(TypedDict, total=False):
 EagerSeriesT_co = TypeVar("EagerSeriesT_co", bound=EagerSeriesAny, covariant=True)
 
 # NOTE: `pyright` gives false (8) positives if this uses `EagerDataFrameAny`?
-EagerDataFrameT = TypeVar("EagerDataFrameT", bound="EagerDataFrame[Any, Any, Any, Any]")
+EagerDataFrameT = TypeVar("EagerDataFrameT", bound="EagerDataFrame[Any, Any, Any]")
 
 LazyExprT = TypeVar("LazyExprT", bound=LazyExprAny)
 LazyExprT_contra = TypeVar("LazyExprT_contra", bound=LazyExprAny, contravariant=True)
diff --git a/narwhals/_pandas_like/dataframe.py b/narwhals/_pandas_like/dataframe.py
index c23748d016..bf5287fbad 100644
--- a/narwhals/_pandas_like/dataframe.py
+++ b/narwhals/_pandas_like/dataframe.py
@@ -103,9 +103,7 @@
 )
 
 
-class PandasLikeDataFrame(
-    EagerDataFrame["PandasLikeSeries", "PandasLikeExpr", "Any", "pd.Series[Any]"]
-):
+class PandasLikeDataFrame(EagerDataFrame["PandasLikeSeries", "PandasLikeExpr", "Any"]):
     def __init__(
         self,
         native_dataframe: Any,
diff --git a/narwhals/_pandas_like/namespace.py b/narwhals/_pandas_like/namespace.py
index 7d9df1e1ac..f1c89c0bec 100644
--- a/narwhals/_pandas_like/namespace.py
+++ b/narwhals/_pandas_like/namespace.py
@@ -31,13 +31,7 @@
 
 
 class PandasLikeNamespace(
-    EagerNamespace[
-        PandasLikeDataFrame,
-        PandasLikeSeries,
-        PandasLikeExpr,
-        pd.DataFrame,
-        "pd.Series[Any]",
-    ]
+    EagerNamespace[PandasLikeDataFrame, PandasLikeSeries, PandasLikeExpr, pd.DataFrame]
 ):
     @property
     def _dataframe(self) -> type[PandasLikeDataFrame]:

From e7787bd6bc28f8c245ad26c69fb8b68b72be7351 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Wed, 11 Jun 2025 10:53:00 +0100
Subject: [PATCH 13/14] :art:

---
 narwhals/_arrow/namespace.py | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/narwhals/_arrow/namespace.py b/narwhals/_arrow/namespace.py
index a032c11d7a..42a01924fb 100644
--- a/narwhals/_arrow/namespace.py
+++ b/narwhals/_arrow/namespace.py
@@ -24,10 +24,7 @@
 from narwhals._utils import Implementation
 
 if TYPE_CHECKING:
-    from narwhals._arrow.typing import (
-        ChunkedArrayAny,  # noqa: F401
-        Incomplete,
-    )
+    from narwhals._arrow.typing import Incomplete
     from narwhals._utils import Version
     from narwhals.dtypes import DType
     from narwhals.typing import NonNestedLiteral

From 1d36fbc1d71c2502aa635659a378ccb07d6ac7e3 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Wed, 11 Jun 2025 10:53:30 +0100
Subject: [PATCH 14/14] :art:

---
 narwhals/_pandas_like/namespace.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/narwhals/_pandas_like/namespace.py b/narwhals/_pandas_like/namespace.py
index f1c89c0bec..7d149e4c60 100644
--- a/narwhals/_pandas_like/namespace.py
+++ b/narwhals/_pandas_like/namespace.py
@@ -19,8 +19,6 @@
 from narwhals._pandas_like.utils import align_series_full_broadcast
 
 if TYPE_CHECKING:
-    from typing import Any  # noqa: F401
-
     from narwhals._pandas_like.typing import NDFrameT
     from narwhals._utils import Implementation, Version
     from narwhals.dtypes import DType