Reactive approach to simple imperative task

Question

Application requirements:

• subscribe to two event streams A and B
• for each A event there should be corresponding B event some time later
• the a

Answer 1

Assumptions:

• the B stream is hot,
• You have a return type that can represent a Match or a Mismatch (instead of using OnError/Timeout which will terminate the subscription)

Then this would be fine.

AStream.SelectMany(a =>
    BStream.Where(b => b == a)
        .Select(b => new MatchMade(a, b))
        .Take(1)
        .Timeout(matchTimeout)
        .Catch(ex=>Observable.Return(new NoMatchMade(a)))
)