/// <summary>
/// Aggregate stream values.
/// </summary>
/// <typeparam name="TIn">Type of source stream.</typeparam>
/// <typeparam name="TOut">Type of output stream.</typeparam>
/// <param name="source">Source stream.</param>
/// <param name="initialState">The initial state.</param>
/// <param name="aggregator">The aggregator function.</param>
/// <param name="deliveryPolicy">An optional delivery policy.</param>
/// <param name="name">An optional name for this stream operator.</param>
/// <returns>Output stream.</returns>
public static IProducer <TOut> Aggregate <TIn, TOut>(
this IProducer <TIn> source,
TOut initialState,
Func <TOut, TIn, TOut> aggregator,
DeliveryPolicy <TIn> deliveryPolicy = null,
string name = nameof(Aggregate))
=> source.Aggregate <TOut, TIn, TOut>(
initialState,
(state, input, envelope, emitter) =>
{
var newState = aggregator(state, input);
emitter.Post(newState, envelope.OriginatingTime);
return(newState);
},
deliveryPolicy,
name);
