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Pure Functional HTTP APIs in Scala

Streaming

Explore streaming techniques in pure functional HTTP APIs with Scala. Learn how to merge and group product data streams using fs2 functions like groupAdjacentBy, ensuring efficient, memory-conscious processing. Understand the challenges of transforming streams and how to manage data emitted from databases effectively.

We'll cover the following...

Take 1 - Merging products

Because we believe ourselves to be clever, we pick the simple sledgehammer approach and just run some accumulator on the stream. We need a helper function and some code changes on the stream (e.g., in the route).

Scala
def merge(ps: List[Product])(p: Product): List[Product] =
  ps.headOption.fold(List(p)) { h => 
    if (h.id === p.id)
      h.copy(names = h.names ::: p.names) :: ps.drop(1)
    else
      p :: ps
  }

So this function will take a list (that may be empty) and a Product, and will merge the topmost element (the head) of the list with the given Product. It will return an updated list that either contains an ...