Over the last week or so, I’ve been looking at and playing around with the Streams API in Dart, which has been (in part at least) based on the Rx API, and it’s easy to see the parallels between the two sets of APIs and you can find most of the core Rx APIs on Dart’s Stream type already, but there were a few notable absentees which I have often found useful, such as merge, zip, delay and window.
With these absentees in mind I started a small Dart project called stream_ext (for stream extensions) to port them over, and here are some details of the first couple of functions I have done along with some live demo examples.
The merge function merges two streams into a single unified output stream.
The combineLatest function merges two streams into one by using the supplied selector function whenever one of the streams produces an event.
The delay function creates a new stream whose events are directly sourced from the input stream but each delivered after the specified duration.
The throttle function creates a new stream based on events produced by the specified input, upon forwarding an event from the input stream it’ll ignore any subsequent events produced by the input stream until the flow of new events has paused for the specified duration, after which the last event produced by the input stream is then delivered.
The zip function combines two streams into one by combining their elements in a pairwise fashion, combining the latest value on each stream and producing a new event using the supplied zipper function.
It’s still early days and there are quite a few more useful Rx function I think will be useful to people working with Dart, and I hope you find these extension functions useful and please don’t hesitate to get in touch and leave some feedbacks on the project!
I’m an AWS Serverless Hero and the author of Production-Ready Serverless. I have run production workload at scale in AWS for nearly 10 years and I have been an architect or principal engineer with a variety of industries ranging from banking, e-commerce, sports streaming to mobile gaming. I currently work as an independent consultant focused on AWS and serverless.
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