Use of `isize` for count changes should be generic about differential-dataflow HOT 2 CLOSED

This would fix #6 somewhat cleanly, I think. In the problem example, data are sourced as pairs of type (K,SaneF32), with the goal of accumulating the float components. Now, unfortunately floats do not form a ring (due to associativity, making different sums of the same numbers not cancel). If SaneF32 is replaced by a fixed precision i32 (or i64 if needed) we could then ingest the data as

let (input, stream) = builder.new_input::<(K, (i32, isize))>();
let collections = Collection::new(stream);

The use of the collection would need to be one that accumulates in place (I'm not certain arrange does this at the moment, but it could with a few lines of code), at which point all instances of a single key would have both i32 and isize components accumulated.

from differential-dataflow.

Fixed by #18.

from differential-dataflow.