Combine Observables

Question

Let say I have

A: IObservable<int> 
B: IObservable<int> 

how can I combine these two into

C: IObservable<int> 

which emitted value is a product of last observed values of A and B?

E.g.

A = [ 2   3       1 ]
B = [   2   5  6    ]

then

C = [   4 6 15 18 6 ] 

Answer 1

I'm not terribly good at f# (more like a novice), but this seems to work:

let a = new Subject<int>()
let b = new Subject<int>()

let c = Observable.CombineLatest(a, b, Func<_,_,_>(fun x y -> x * y))

c.Subscribe(fun x -> printfn "%i" x) |> ignore

a.OnNext(2)
b.OnNext(2)
a.OnNext(3)
b.OnNext(5)
b.OnNext(6)
a.OnNext(1)

I get:

4
6
15
18
6