There's a fun video of [Paul Phillips ragging on Scala][1], and particularly collections. There's a point in it where [he discusses size][2], and basically says it's stupid for all collections to have a size, and for it to be an integer, since it may well be infinite, undefined, or too expensive to compute for it to be meaningful. An example of the latter is a convergent sequence where the size is unknown until the sequence has been fully calculated, which may well be very expensive; a ray tracer comes to mind, where the sequence light calculations in a scene must converge (at least on a limit) before it can be considered "complete" and thus have a defined size. As it were, this size is largely irrelevant anyway, since it's curiosity more than anything, it's not going to help in any meaningful way. In some cases it might, and one I can immediately think of is averaging results of sampling light on a surface (again, in the ray tracing context) but in such a case you'll `take(n)` number of samples where `n` is most likely a predefined maximum, or less in case the size is smaller than `n`.

I have a feeling that size, or `length` as it's called in the code above, is largely just curiosity and an implementation detail for making `count` faster (which could probably be done by other means *anyway*,) but not actually a meaningful or relevant property of a sequence. I'm inclined to remove it.

[1]: https://www.youtube.com/watch?v=uiJycy6dFSQ
[2]: https://www.youtube.com/watch?v=uiJycy6dFSQ&feature=youtu.be&t=35m32s