We have introduced the handy fetch.debug.describe function for debugging errors, but it can do more than that. It can also give you a detailed description of a fetch execution given an execution log.

Add the following line to your dependencies for including Fetch’s debugging facilities:

"com.47deg" %% "fetch-debug" % "1.2.1"

Fetch execution

We are going to create an interesting fetch that applies all the optimizations available (caching, batching and concurrent request) for ilustrating how we can visualize fetch executions using the execution log.

def batched[F[_]: Concurrent]: Fetch[F, List[User]] =
  List(1, 2).traverse(getUser[F])

def cached[F[_]: Concurrent]: Fetch[F, User] =

def notCached[F[_]: Concurrent]: Fetch[F, User] =

def concurrent[F[_]: Concurrent]: Fetch[F, (List[User], List[Post])] =
  (List(1, 2, 3).traverse(getUser[F]), List(1, 2, 3).traverse(getPost[F])).tupled

def interestingFetch[F[_]: Concurrent]: Fetch[F, String] =
  batched >> cached >> notCached >> concurrent >> Fetch.pure("done")

Fetch.runLog[IO](interestingFetch).unsafeRunSync()._2 shouldBe res0