LensStates.scala

  object Test {   
    import scalaz.{Lens,State}   
    case class BlahConfig(server: Int, l: List[Int]) 
     
    def doStuff(i: Int) = State[BlahConfig,Int]( c => (c.copy(l = i :: c.l), c.server) ) 
   
    case class FooConfig(val password: String) 
   
    def doSomeStuff(i: Int) = State[FooConfig, String](c =>(c, c.password)) 
    
    //CONCCRETE CONFIG 
    case class RConfig(s: Int, p: String, l: List[Int])  
       
    //A way to go from a 'smaller' type to a bigger type
    val l1 = Lens.lensu[RConfig, BlahConfig]( (a,b) => a.copy(s = b.server, l = b.l), b => BlahConfig(server=b.s, l = b.l)) 
     
    val l2 = Lens.lensu[RConfig, FooConfig]( (a,b) => a.copy(p = b.password), b => FooConfig(password = b.p))  
     
    val res = for { 
      a <- doStuff(2).zoom(l1) 
      b <- doSomeStuff(a).zoom(l2) 
    } yield a + b
    
    res(RConfig(1, "asdf", List(1)))
}