ReaderSequenced.scala

import cats.data._
import cats.syntax.traverse._
import cats.std.list._
import scala.util.Try


def tryInt(s: String): Try[Int] = Try(s.toInt)

def reader: Reader[Try[Int], String] = Reader[Try[Int], String] { t =>
  t.map(s => s"$s is a number").getOrElse("not")
}


val listReader1 = List(reader, reader, reader)
val listReader2 = List(reader, reader, reader)

val readers = listReader1 ++ listReader2
val sequenced: Reader[Try[Int], List[String]] = readers.sequenceU

sequenced(tryInt("1"))
//res0: cats.Id[List[String]] = List(1 is a number, 1 is a number, 1 is a number, 1 is a number, 1 is a number, 1 is a number)
sequenced(tryInt("hola"))
//res1: cats.Id[List[String]] = List(not, not, not, not, not, not)

How to: http://typelevel.org/cats/tut/traverse.html