Machines and Argonaut

gistfile1.scala

import scala.util.Try

import scalaz._, Scalaz._
import scalaz.effect._, IO._

import com.clarifi.machines._

import argonaut._, Argonaut._

object Sample extends SafeApp {

  def getUser = jArrayPL.getK >==> (_.headOption)

  def text = jObjectPL >>> jsonObjectPL("status") >>> jObjectPL >>> jsonObjectPL("text") >>> jStringPL

  def parse(json: String) = json.parse.fold(Some.apply, getUser >=> text.getK).orZero

  def lookup = new Driver[IO, String => Any] {
    val M = Monad[IO]
    def apply(k: String => Any) = for {
      name <- readLn
      url = s"http://api.twitter.com/1/users/lookup.json?screen_name=$name"
    } yield Try(scala.io.Source.fromURL(url).mkString).toOption
  }

  def loop = new Procedure[IO, String] {
    type K = String => Any
    val machine = Process(parse)
    def withDriver[R](k: Driver[IO, K] => IO[R]) = k(lookup)
  }

  override def runc = loop foreach putStrLn

}