CODEWITHSUNDEEP
scalascalaz-streamfs2
clay
clay

Reputation: 20460

Scala fs2 Streams with Chunks and Tasks?

  // Simulated external API that synchronously returns elements one at a time indefinitely.
  def externalApiGet[A](): A = ???

  // This wraps with the proper fs2 stream that will indefinitely return values.
  def wrapGetWithFS2[A](): Stream[Task, A] = Stream.eval(Task.delay(externalApiGet))

  // Simulated external API that synchronously returns "chunks" of elements at a time indefinitely.
  def externalApiGetSeq[A](): Seq[A] = ???

  // How do I wrap this with a stream that hides the internal chunks and just provides a stream of A values.
  // The following doesn't compile. I need help fixing this.
  def wrapGetSeqWithFS2[A](): Stream[Task, A] = Stream.eval(Task.delay(externalApiGetSeq))

Upvotes: 0

Views: 1269

Answers (1)

sortega
sortega

Reputation: 1158

You need to mark the sequence as a Chunk and then use flatMap to flatten the stream.

def wrapGetSeqWithFS2[A](): Stream[Task, A] =
  Stream.eval(Task.delay(externalApiGetSeq()))
    .flatMap(Stream.emits)

(Edited to simplify solution)

Upvotes: 3

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