On 24/03/2015 at 20:07:00 +0100, martin wrote:
My temporal type is defined as follows
data Change a = Chg { ct :: Time, -- "change time" cv :: a -- "change value" }
data Temporal a = Temporal { td :: a, -- "temporal default" tc :: [Change a] -- "temporal changes" } deriving (Show)
I started off with "Event" instead of "Change", but found this misleading. Two successive changes with the same value have the same effect as a single change, while for Events in the sense of "left button click" there is a difference between a click and a doubleclick.
As you have it, yes. One could alternately define data Change a = Chg { ct :: Time, c :: a -> a } in which case changes would not in general be idempotent, and idempotent changes would have form Chg { ct = _, c = pure _ }.
I don't know if I'll ever have to intersperse Changes from two lists. In that case two successive changes to the same value *will* make a difference, because the second change my undo the effect of an interspersed change.
Seems a good reason to keep multiplicates in the list ☺
I am still somewhat struggeling with train schedules. I'd love to craft an example with a summer and a winter schedule, but I don't quite know what to use as a value. Intuitively it'd be something like "departure time", but of what? I am not sure if there is a missing piece, or if I just have to turn away from traditional train schedules and us "train on track 1" as the changing value.
Each train could have a Temporal Location. Which definition makes sense is a function of what you want to ask of the schedules.