Http4s EntityEncoder for returning Streams as JSONArrays using Circe.

StreamAsJsonArrayEncoder.scala

import cats.Applicative
import cats.effect.IO
import fs2.Stream
import io.circe.Encoder
import io.circe.generic.semiauto.deriveEncoder
import io.circe.syntax.EncoderOps
import org.http4s.{EntityEncoder, MediaType}
import org.http4s.dsl.io._
import org.http4s.headers.`Content-Type`

import scala.language.higherKinds

/** EntityEncoder for Streams of T values, which will encode them as a JSONArrays */
implicit def streamAsJsonArrayEncoder[F[_], T](implicit F: Applicative[F], tEncoder: Encoder[T]): EntityEncoder[F, Stream[F, T]] =
  EntityEncoder
    .streamEncoder[F, String]
    .contramap[Stream[F, T]](stream => Stream.emit("[") ++ stream.map(t => t.asJson.noSpaces).intersperse(",") ++ Stream.emit("]"))
    .withContentType(`Content-Type`(MediaType.`application/json`))

/** Simple case class */
final case class Data(
    id: Int,
    name: String
)

/** Circe JSON encoder for our simple case class */
implicit val dataCirceEncoder: Encoder[Data] = deriveEncoder

/** Test the Encoder */
Ok(Stream(Data(id = 3, name = "BalmungSan"), Data(id = 5, name = "Luis Miguel Mejía Suárez")).covary[IO]).unsafeRunSync
// Response(status=200, headers=Headers(Transfer-Encoding: chunked, Content-Type: application/json))
// Body: "[{"id":3,"name":"BalmungSan"},{"id":5,"name":"Luis Miguel Mejía Suárez"}]"