Add proper eq and ord instances for ZonedTime

[pharpend]

No description provided.

[AshleyYakeley]

Rejected, because this finds "midnight +00:00" == "1am +01:00" to be True, when they are clearly different values of ZonedTime.

Additionally, ZonedTime just isn't morally an instance of Ord. There should not be an "instance Ord ZonedTime".

[pharpend]

Rejected, because this finds "midnight +00:00" == "1am +01:00" to be True, when they are clearly different values of ZonedTime.

They are quite obviously the same time.

[AshleyYakeley]

They're not the same ZonedTime. A ZonedTime isn't precisely a time. It's a time (or a LocalTime) together with a TimeZone. From a ZonedTime you can derive a LocalTime, a TimeZone, and a UTCTime, but a ZonedTime isn't any one of these things.

[hvr]

They are quite obviously the same time.

This depends on what you consider the exact definition of Eq/Ord (or rather "same time").

And I agree with @AshleyYakeley here that algebraically, ZonedTime is not a totally ordered set, and thus can't have a (total) Ord instance.

If you need to compare two ZonedTimes you can always normalise them and use something like comparing zonedTimeToUTC which makes your semantics much more explicit.