On 30/03/2015 at 22:23:17 +0200, martin wrote:
Hello all,
I wrote a Temporal datatype
data Temporal a = Temporal { td :: a, -- "temporal default" tc :: [Change a] -- "temporal changes" } deriving (Eq, Show)
data Change a = Chg { ct :: Time, -- "change time" cv :: a -- "change value" } deriving (Eq,Show)
I got into semantic trouble when trying to write "join" for Temporal (Temporal a).
It appears to me that the defaults of the inner Temporal lose most of their meaning. The effective default is the change value of the last accepted change from the previous (t0) iteration.
Does this make some sense? Please feel free to comment.
Yes, as the default value is essentially a change at the lower bound of time, 0 or -∞ or whenever it is, so if we join Temporal x [Change t1 (Temporal y _)] the change to y in the inner Temporal would happen at earliest possible time, so assuming t1 is later than this y ought to be ignored, I think.