I think Span really goes way beyond what ArraySegment was intended to do. ArraySegment was just a way of wrapping the very common 3 parameters (Array, offset, l

I think Span really goes way beyond what ArraySegment was intended to do. ArraySegment was just a way of wrapping the very common 3 parameters (Array, offset, length) used in almost any buffer copy operation into a single object. Span/slice was a much more ambitious type that not only provided fast array segment like access, but also introduced a way to provide typed views into byte[] without the cost of casting or copying memory. Span<T> is low level enough that they considered calling it Array<T> but decided against it to avoid even more confusion. If you want to see an example of a API failure it is with System.Tuple<>. That type is effectively being deprecated when ValueTuple comes into the BCL with proper compiler support.