Usage

import no.scalabin.http4s.directives._
import cats.effect.IO
import org.http4s._
import org.http4s.dsl.io._
import org.http4s.dsl.impl.Root

implicit val Direct: Directives[IO] = Directives[IO]

import Direct._
import ops._

val Mapping = Plan[IO]().Mapping(req => Path(req.uri.path))

val service = HttpService[IO] {
  Mapping {
    case Root / "hello" => 
      for {
        _ <- Method.GET
        r <- Ok("Hello World").successF
      } yield r
  }
}

val bodyService = HttpService[IO] {
  Mapping {
    case Root / "hello" => 
      for {
        _    <- Method.POST
        body <- request.bodyAs[IO, String]
        r    <- Ok(s"echo $body").successF
      } yield r
  }
}

val queryParamService = HttpService[IO] {
  Mapping {
    case Root / "hello" => 
      for {
        _         <- Method.POST
        name      <- request.queryParam[IO]("name")
        items     <- request.queryParams[IO]("items")
        nickname  <- request.queryParamOrElse[IO]("nickname", BadRequest("missing nickname"))
        r         <- Ok(s"Hello $name($nickname): ${items.mkString(",")}").successF
      } yield r
  }
}