a bit less broken

narwhals/dataframe.py

@@ -19,7 +19,6 @@
 
 
 def extract_native(obj: Any, implementation: str) -> Any:
-    from narwhals.expression import PandasExpr
     from narwhals.series import Series
 
     # if isinstance(obj, NarwhalsExpr):

narwhals/expression.py

@@ -1,11 +1,13 @@
 from __future__ import annotations
 
-from typing import Any, TYPE_CHECKING
-from typing import Iterable, Callable
+from typing import TYPE_CHECKING
+from typing import Any
+from typing import Callable
+from typing import Iterable
 
 if TYPE_CHECKING:
-    from narwhals.polars import Expr
     from narwhals.pandas_like.expr import PandasExpr
+    from narwhals.polars import Expr
 
 
 def extract_native(expr: Expr, other: Any) -> Any:

narwhals/pandas_like/utils.py

@@ -97,13 +97,14 @@ def parse_into_exprs(
 
 
 def parse_into_expr(implementation: str, into_expr: IntoExpr) -> PandasExpr:
-    from narwhals.expression import PandasExpr
+    from narwhals.expression import Expr
+    from narwhals.pandas_like.expr import PandasExpr
     from narwhals.pandas_like.namespace import Namespace
     from narwhals.pandas_like.series import PandasSeries
 
     plx = Namespace(implementation=implementation)
 
-    if isinstance(into_expr, PandasExpr):
+    if isinstance(into_expr, Expr):
         return into_expr._call(plx)
     if isinstance(into_expr, str):
         return plx.col(into_expr)

narwhals/polars.py

@@ -26,11 +26,11 @@
 
 
 def extract_native(obj: Any) -> Any:
-    from narwhals.expression import PandasExpr
+    from narwhals.expression import Expr
 
-    if isinstance(obj, PandasExpr):
+    if isinstance(obj, Expr):
         return obj._call(pl)
-    if isinstance(obj, PandasExpr):
+    if isinstance(obj, PolarsExpr):
         return obj._expr
     if isinstance(obj, DType):
         return obj._dtype