| > And once you have that, maybe they could all return the
| > same type (TimeDiff) and then the need for the class goes away.
| > diffMinutes :: ClockTime -> ClockTime -> TimeDiff
| I suppose TimeDiff is then a disjunction (Minutes of Int |
| Days of Int | etc.)
| But I don't really see the point. The type is now
| considerably less efficient
| and the compiler has to worry about an entirely bogus
| matching failure in
| cass (diffMinutes t1 t2) of
| Minutes N -> [blah]
| What is so bad about having another class anyway?
It's not terrible. But all the types are isomorphic to Int,
so there'd be a case for making them Ints.
diffDays :: Time -> Time -> Int
addDays :: Time -> Int -> Time
diffMonths :: Time -> Time -> Int
addMonths :: Time -> Int -> Time
Then it's easy to do things like
date `addDays` 3
whereas in your formulation you'd have to say
date `addToClockTime` Days 3
Not a big difference, I grant you, but my own taste
is to keep overloading for where it makes a real difference,
and it just doesn't seem to here.
Simon
