circe-fs2 example

build.sbt

lazy val fs2Version = "0.9.7"
lazy val circeVersion = "0.8.0"

lazy val root = (project in file("."))
  .settings(
    name := "circe-fs2-example",
    scalaVersion := "2.12.3",
    libraryDependencies ++=
      "co.fs2" %% "fs2-io" % fs2Version +: Seq(
      "io.circe" %% "circe-generic",
      "io.circe" %% "circe-fs2"
    ).map(_ % circeVersion)
  )

main.scala

import _root_.fs2.{io, text, Task, Stream}
import _root_.io.circe.Json
import _root_.io.circe.fs2._
import _root_.io.circe.generic.auto._
import java.nio.file.Paths

object Main {
  case class Popularity(repo: String, stars: Int)

  def main(args: Array[String]): Unit = {

    val stringStream: Stream[Task, String] =
      io.file.readAll[Task](Paths.get("popularity.json"), 4096)
        .through(text.utf8Decode)

    val parsedStream: Stream[Task, Json] =
      stringStream.through(stringParser)

    val popularityStream: Stream[Task, Popularity] =
      parsedStream.through(decoder[Task, Popularity])

    println(popularityStream.runLog.unsafeAttemptRun())
  }
}

popularity.json

[
    {
        "repo": "circe-fs2",
        "stars": 13
    },
    {
        "repo": "circe-yaml",
        "stars": 32
    }
]