Make `int_range()` and `int_ranges()` work with no inputs and default to `int_range(0, pl.len())` about polars HOT 7 OPEN

Actually, not a coincidence I saw the bump and it reminded me of asking for this default.

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Chiming in, I think pl.index() is better than pl.row_index(). It's simpler, and all horizontal expressions use horizontal_, so the "row" part is unnecessary.

It also seems to be a super obvious operation and very common to use, why is there any argument about it?

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Coincidentally, the pl.row_index() issue received a bump earlier today.

#12420

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@ritchie46 is this one ok to do or do you have any objections?

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This feels counter-intuitive to me: I would expect a range function called without specified bounds to raise.
Adding pl.row_index() (with the same implementation you propose) to the API would make more sense in my opinion.

EDIT: Furthermore, pl.int_range() could not be used as a join expression since it doesn't return an elementwise expression (see #12420 (comment))

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@mcrumiller I, for one, am not arguing against pl.index or pl.row_index or whatever other name it could have. It's just that those were already ruled out so this is a middle ground.

@Oreilles Lots of things are counterintuitive until you get used to them. That said, I don't really share that sense of it being counterintuitive since it exists in a context that has a length that is a natural default so why not make it the default?

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Intuitiveness certainely is subjective, but using pl.int_range() to generate an index has some drawbacks that would cripple its use case compared to an actual row_index function.

• int_range doesn't reflex the intent in the way row_index or with_row_index does (would with_int_range make sense ? Maybe, but arguably less intuitively).
• int_range defaults to Int64 and index columns generated with with_row_index are UInt32, so they cannot be merged on by default.
• int_range cannot be used as a join expression... which would likely be the primary use case for using it instead of with_row_index (see #12420 (comment))

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