Programming in Scala”

Errata 4
run(listOfN(3, "ab" | "cad"))("ababcad") == Right(List("ab","ab","cad"))
run(listOfN(3, "ab" | "cad"))("cadabab") == Right(List("cad","ab","ab"))
run(listOfN(3, "ab" | "cad"))("ababab") == Right(List("ab","ab","ab"))
Pg 184: Exercise 10.13 incorrectly defines Leaf as a case object. It should be case class:
case class Leaf[A](value: A) extends Tree[A]
Pg 187: Definition of signature for map on Option has incorrect return type, should be:
def map[A,B](oa: Option[A])(f: A => B): Option[B]
Pg 238: Definition of printLine has a typo, an extra Return constructor, should be:
def printLine(s: String): IO[Unit] = Suspend(() => println(s))
Pg 240: REPL session has a typo, should be:
val g = List.fill(100000)(f).foldLeft(f) {
}
(a, b) => x => Suspend(() => ()).flatMap { _ => a(x).flatMap(b)}
Note: we could write a little helper function to make this nicer:
def suspend[A](a: => IO[A]) = Suspend(() => ()).flatMap { _ => a }
val g = List.fill(100000)(f).foldLeft(f) {
}
(a, b) => x => suspend { a(x).flatMap(b) }
Pg 241: TrailRec should be TailRec at the top of the page.
Pg 285: Code snippet has an incorrectly named type parameter, currently reads:
case class Await[A,O](
req: Is[I]#f[A], recv: Either[Throwable,A] => Process[Is[I]#f,O]
) extends Process[Is[I]#f,R] // `R` should be `O`
Should read: