This is related to several comments in #201 and is an extension of the work done as part of #194.

In many cases sample_indicies can be a u32 or even a u16 (u8 is probably not worth it) to save on performance and memory usage. This applies to both the cache and inplace implementations. This ticket is to investigate what it would take to make the function generic.

This should not be (much of) a breaking change, since in most cases type inference would infer the usize requirement. However, it would be a potentially minor one.