Is `abstract_array.length` needed when we have `count` already?

[michaellilltokiwa]

My hunch currently is that we should just drop length

[fridis]

Nope. Semantically, they both return the length. The difference is that length guarantees to be in O(1) while count might be in O(result). So, whenever you see count, alarm bells should ring!

What is missing is better documentation of these complexities.

[michaellilltokiwa]

@fridis Okay, but one could argue that if finite = finite.yes then count is also guaranteed to be O(1)

[fridis]

@fridis Okay, but one could argue that if finite = finite.yes then count is also guaranteed to be O(1)

For a Sequence, this is not the case, we can very well imagine a Sequence that is finite but that does not store the count explicitly but performs O(count) counting on every call to count.