JarCastingjawn-fs2 
Asynchronously parse fs2 streams to JSON values with jawn.
Example
sbt test:run to see it in action:
package com.example
import cats.effect.{IO, IOApp, ExitCode}
import fs2.{io, text, Stream}
import fs2.io.file.Files
import java.nio.file.Paths
import jawnfs2._
import scala.concurrent.duration._
object Example extends IOApp {
// Pick your favorite supported AST (e.g., json4s, argonaut, etc.)
implicit val facade = org.typelevel.jawn.ast.JawnFacade
def run(args: List[String]) = {
// From JSON on disk
val jsonStream = Files[IO].readAll(Paths.get("testdata/random.json"), 64)
// Simulate lag between chunks
val lag = Stream.awakeEvery[IO](100.millis)
val laggedStream = jsonStream.chunks.zipWith(lag)((chunk, _) => chunk)
// Print each element of the JSON array as we read it
val json = laggedStream.unwrapJsonArray
.map(_.toString)
.intersperse("\n")
.through(text.utf8Encode)
// run converts the stream into an IO, unsafeRunSync executes the IO for its effects
json.through(io.stdout).compile.drain.as(ExitCode.Success)
}
}
Migration note
In jawn-fs2-2.x, the root package changes from jawn.fs2 to org.typelevel.jawn.fs2.
Add jawn-fs2 to your project
Add to your build.sbt:
// For cats-effect-2
libraryDependencies += "org.http4s" %% "jawn-fs2" % "1.0.0"
// For cats-effect-3
libraryDependencies += "org.typelevel" %% "jawn-fs2" % "2.0.0-M2"
// Pick your AST: https://github.com/non/jawn#supporting-external-asts-with-jawn
libraryDependencies += "org.typelevel" %% "jawn-ast" % "1.0.0"
Compatibility matrix
| Stream Library | You need... | Status |
|---|---|---|
| fs2-3.x | "org.typelevel" %% "jawn-fs2" % "2.0.0-M2" |
milestone |
| fs2-2.x | "org.http4s" %% "jawn-fs2" % "1.0.0" |
stable |
| fs2-1.x | "org.http4s" %% "jawn-fs2" % "0.14.2" |
EOL |
| fs2-0.10.x | "org.http4s" %% "jawn-fs2" % "0.12.2" |
EOL |
| fs2-0.9.x | "org.http4s" %% "jawn-fs2" % "0.10.1" |
EOL |
| scalaz-stream-0.8a | "org.http4s" %% "jawn-streamz" % "0.10.1a" |
EOL |
| scalaz-stream-0.8.x | "org.http4s" %% "jawn-streamz" % "0.10.1" |
EOL |
The legacy scalaz-stream artifacts are on the jawn-streamz branch.
