public static Optional <TResult> ChangesTo <TArgs, TResult>(
this OptionalPreviousCurrentTuple <TArgs> self,
Func <TArgs, TResult> select)
{
var prev = self.Previous.Select(select);
var cur = select(self.Current);
if (prev.Equals(cur))
{
return(Optional.None());
}
return(cur);
}
public static IObservable <OptionalPreviousCurrentTuple <T> > BufferPrevious <T>(this IObservable <T> self)
{
return(Observable.Create <OptionalPreviousCurrentTuple <T> >(
observer =>
{
var previous = Optional.None <T>();
return self
.Select(current =>
{
var ret = new OptionalPreviousCurrentTuple <T>(previous, current);
previous = current;
return ret;
})
.Subscribe(observer);
}));
}