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Python Performance: Why 'if not list' is 2x Faster Than Using len() (blog.codingconfessions.com)
submitted 1 year ago by to c/technology@lemmy.world
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[–] 1 point 1 year ago (2 children)

Doesn't Python treat all empty iterables as false tho? This isn't unique to python, is it? (though I'm not a programmer...just a dude who writes scripts every now and then)

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  • [–] 3 points 1 year ago (1 child)

    My point is that the second statement you presented can have the effect of evaluating emptiness of a Sequence (note: distinct from an Iterable), but that only holds true if the target of the conditional IS a sequence. I’m underlining the semantic difference that was elided as a result of falsey evaluation.

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  • [–] 1 point 1 year ago (2 children)

    Ok, help a noob out. What is the difference between a sequence and an iterable? Is a sequence immutable, like a tuple?

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  • [–] 1 point 1 year ago*

    thing: Sequence[Any] iirc is iterable, indexable, and reversible.

    thing: Iterable[Any] only guarantees that its iterable - and note that iterating can sometimes have the effect of consuming the iterable (e.g. when working with streaming interfaces)

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  • [–] 1 point 1 year ago (1 child)

    An iterable is just something that can be iterated over, like range(10), or [1, 2, 3].

    A sequence on the other hand is a Collection that is reversible.

    https://docs.python.org/3/library/collections.abc.html#collections-abstract-base-classes

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