Example of trampolining iteratees with scalaz 7

gistfile1.scala

import scalaz._
import Scalaz._
import scalaz.iteratee._
import EnumeratorT._

def counter[A, F[+_]: Pointed] =
  IterateeT.fold[A, F, Int](0) { (acc: Int, a: A) => acc + 1 }

def count[A, F[+_]: Monad](e: EnumeratorT[A, F]) =
  (counter[A, F] &= e).run

require (count(enumList[Int, Id](List(1, 2, 3))) === 3)

val largeStream = Stream.range(1, 100001, 1)

try {
  (counter[Int, Id] &= enumStream[Int, Id](largeStream))
  require (false, "Should have thrown stack overflow")
} catch {
  case _: StackOverflowError =>
}

import Free._
require (count(enumList[Int, Trampoline](List(1, 2, 3))).run === 3)
require ((counter[Int, Trampoline] &= enumStream[Int, Trampoline](largeStream)).run.run === largeStream.size)