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Comment by maxcoder4 | Hacker News Reader

>That's the complaint, that [[]]*4 is not shorthand for list comprehensions and that it's something entirely different.

Well, of course. It's a shorthand for duplicating the list elements four times. In this case, the list contains a single reference to an empty list, do the result contains four references to an empty list.

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And it's literally impossible for [[]]*4 to be a shorthand for a list comprehension, because nothing in Python can be a shorthand for a list comprehension. Instead, it is but a method call.

I mean, there is no reason Python couldn't special case something that looked like an operator call into shorthand for a comprehension instead of shorthand for a method call, other than the fact that it would make the parser more complex and make it harder to understand the language.

It would be bad for this case, though. As confusing as the particular case of:

  [[]] * 4

might be to people who haven't learned how it works, list multiplication doesn't just apply to single element lists, and is useful and usefully distinct from what people are suggesting the behavior should be for the operation based on this one case.

Well, Python is not Raku, so while it could be possible to make "[expr1, expr2, ..., exprN] * exprM" to mean "[*(expr1), *(expr2), ..., *(exprN) for _ in range(exprM)]", it would never happen.

Besides, that still doesn't help with the case of

    x = function_that_returns_a_list()
    x = x * 4

where there is no literal list expression.

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