Allows a faster downstream to progress independently of a slower publisher by extrapolating elements from an older element until new element comes from the upstream. For example an expand step might repeat the last element for the subscriber until it receives an update from upstream. This element will never "drop" upstream elements as all elements go through at least one extrapolation step. This means that if the upstream is actually faster than the upstream it will be backpressured by the downstream subscriber. Expand does not support Restart and Resume. Exceptions from the extrapolate function will complete the stream with failure.

Emits when downstream stops backpressuring

Backpressures when downstream backpressures

Completes when upstream completes

Cancels when downstream cancels

public static Source<TOut2, TMat> Expand<TOut1, TOut2, TMat>(
	this Source<TOut1, TMat> flow,
	Func<TOut1, IEnumerator<TOut2>> extrapolate
)

[<ExtensionAttribute>]
static member Expand : 
        flow : Source<'TOut1, 'TMat> * 
        extrapolate : Func<'TOut1, IEnumerator<'TOut2>> -> Source<'TOut2, 'TMat>