Spans are certainly a bit unfortunate, and are something I wish were backed by `nint` instead of `int`. But those came to the language later and it wasn't covered as part of the initial design.

That being said, it is largely in the same boat where if you're working with more than 2GB of memory in a single allocation, you're not necessarily going to have a good time. Even if your phone has 12GB of memory, you in practice get a much smaller portion of that available for actual usage and you don't want to cap out the available RAM either since that will cause thrashing and other issues.

75-80% of available physical RAM is about what you want to cap out at, and that's if you're the only app really using any resources.

MemoryMapped files notably support 64-bit values today and have since they were introduced. As have streams in general.

Streaming tensors can make sense and is necessary with extremely large models. The CPU cannot handle all data at once and the cost of loading everything from disk is often expensive, so you'll want to balance loading in data you need in the short term with data that isn't needed anymore or will only be needed in the long term.

Streaming or otherwise chunking your data can likewise help with parallelization and while there are some domains where chunking isn't possible, streaming always is. It just comes down to data size to determine if its beneficial or not.