On 2026-07-02 05:22, Tim Düsterhus wrote:
To close this out ourselves: While having a static `sum()` method works
for `Duration`s, since the Duration with addition forms an abelian
group, this doesn't work for the other future-scope classes where
addition doesn't form an (abelian) group. More specifically: Adding two
Instants together is not a meaningful operation. Adding a Duration to an
Instant however is.
If you want the appropriate mathematical structure, the timeline models
a one-dimensional real affine space, in which Durations are vectors and
Instants are points; it's a vector space that has forgotten its origin
(the choice of epoch is arbitrary and not a distinguished point of the
space - as evidenced by how many of them there are).
