public static IObservable <T> AggregateAssoc <T>(
this IObservableList <T> self,
T seed,
Func <T, T, T> associativeAccumulator)
{
return(self
.Scan(
SumTree <T> .Empty(seed, associativeAccumulator),
(tree, changes) => changes.Apply(tree))
.Select(tree => tree.Sum()));
}
public static IObservable <int> Count <T>(this IObservableList <T> self)
{
return(self.Scan(0,
(count, change) =>
{
change(
insert: (i, item) => ++ count,
replace: (i, item) => { },
remove: i => -- count,
clear: () => count = 0);
return count;
}).DistinctUntilChanged());
}
public static IObservable <ImmutableList <T> > ToObservableImmutableList <T>(this IObservableList <T> self)
{
return(self.Scan(
ImmutableList <T> .Empty,
(list, changes) => changes.Apply(list)));
}
