What is the recommended way to convert DeltaQuantity to Quantity?

[benhutchison]

I have a bunch of millisecond timestamps modeled as DeltaQuantitys.

I need to bin them into groups n seconds wide. That is, all timestamps within a time period of n seconds should be mapped to the same group (ie index).

To do this requires dividing the timestamp quantities by the window width. But I can't divide a DeltaQuantity by a Quantity directly. Rather, I ought to convert the DeltaQuantity into a Quantity.

I found myself wanting a toQuantity operation for DeltaQuantity that yields a quantity using whatever origin/zero is defined naturally by that DeltaQuantity. Making a separate zero value and subtracting it from each timestamp feels like quite a lot of bother..

[benhutchison]

extension [VL, UL, B] (d: DeltaQuantity[VL, UL, B])
  def toQuantity: Quantity[VL, UL] = d.value.withUnit[UL]

[erikerlandson]

Your expression d.value.withUnit[UL] is the way to do it now. In the scala2 version, I actually supported a .toQuantity method, and I made the decision to not support it in scala3, because I felt like it violated the subtle but important semantic differences between DeltaQuantity and Quantity. If you want to convert it, the "algebraically correct" way would probably be something like d - zero, where zero would be the DeltaQuantity for posix epoch for time, and zero Kelvin for Temperature.

I'm currently reluctant to provide it but I can think about it some.