list arithmetic output dtype solely dependent on the first operand

[jackaixin]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

df1 = pl.DataFrame({
    'i': [1, 2, 3],
    'b': [True, True, False],
    'f': [1., 2., 3.]
})

df1.with_columns(
    (pl.col('i') + pl.col('b')).alias('i+b'),
    (pl.col('i') + pl.col('f')).alias('i+f'),
    (pl.col('b') + pl.col('i')).alias('b+i'),
    (pl.col('b') + pl.col('f')).alias('b+f'),
    (pl.col('f') + pl.col('i')).alias('f+i'),
    (pl.col('f') + pl.col('b')).alias('f+b'),
)

df2 = pl.DataFrame({
    'i': [[1, 2, 3]],
    'b': [[True, True, False]],
    'f': [[1., 2., 3.]],
})

df2.with_columns(
    (pl.col('i') + pl.col('b')).alias('i+b'),
    (pl.col('i') + pl.col('f')).alias('i+f'),
    (pl.col('f') + pl.col('b')).alias('f+b'),
    (pl.col('f') + pl.col('i')).alias('f+i'),
)

try:
    df2.with_columns(
        (pl.col('b') + pl.col('i')).alias('b+i'),
    )
except pl.exceptions.PanicException as e:
    print(e)

try:
    df2.with_columns(
        (pl.col('b') + pl.col('f')).alias('b+f'),
    )
except pl.exceptions.PanicException as e:
    print(e)

Log output

No response

Issue description

In df1 where we do regular arithmetic, we see that the output dtypes are supertypes of both operands.

• bool + int -> int
• bool + float -> float
• int + bool -> int
• int + float -> float
• float + bool -> float
• float + int -> float

However, in the list arithmetic operations for df2, we see that

• list[int] + list[bool] -> list[int] (expected)
• list[int] + list[float] -> list[int] (unexpected)
• list[float] + list[bool] -> list[float] (expected)
• list[float] + list[int] -> list[float] (expected)
• list[bool] + list[int] -> PanicException
• list[bool] + list[float] -> PanicException

Expected behavior

• list[int] + list[bool] -> list[int]
• list[int] + list[float] -> list[float]
• list[float] + list[bool] -> list[float]
• list[float] + list[int] -> list[float]
• list[bool] + list[int] -> list[int]
• list[bool] + list[float] -> list[float]

Installed versions

--------Version info---------
Polars:              1.8.2
Index type:          UInt32
Platform:            macOS-15.0-arm64-arm-64bit
Python:              3.11.9 (main, Apr  2 2024, 08:25:04) [Clang 15.0.0 (clang-1500.3.9.4)]

----Optional dependencies----
adbc_driver_manager  1.2.0
altair               5.4.1
cloudpickle          3.0.0
connectorx           0.3.3
deltalake            0.20.1
fastexcel            0.11.6
fsspec               2024.9.0
gevent               24.2.1
great_tables         0.12.0
matplotlib           3.8.2
nest_asyncio         1.6.0
numpy                1.26.2
openpyxl             3.1.5
pandas               2.1.4
pyarrow              17.0.0
pydantic             2.9.2
pyiceberg            0.7.1
sqlalchemy           2.0.35
torch                <not installed>
xlsx2csv             0.8.3
xlsxwriter           3.2.0