foldable1.scala

case class ScalaChan[A](values: A*)

implicit def ScalaChanFoldable = new Foldable[ScalaChan] {
  override def foldMap[A, M: Monoid](t: ScalaChan[A], f: (A) => M): M = t.values.map(f).fold(mzero[M])(_ |+| _)
}

ScalaChan(1, 2, 3, 4).foldMap(identity) assert_=== 10

foldable2.scala

nel("Hello", "Scalaz").foldr(none[String])(_.some |+| _) assert_=== Some("HelloScalaz")

List('Scalaz, 'Scala).foldl('Scalaちゃん.wrapNel)(_ |+| _.wrapNel) assert_=== NonEmptyList('Scalaちゃん, 'Scalaz, 'Scala)

foldable3.scala

nil[Int].foldl1(_ * _) assert_=== None

nel(1, 2, 3).foldr1(_ * _) assert_=== Some(6)

foldable4.scala

nel(3, 4, 6).foldRightM(6)((a, b) => b +>: a.wrapNel) assert_=== NonEmptyList(6, 3, 4, 3, 6, 3, 4, 3)

nel("10", "Scala").foldLeftM(10)((i, s) => s.parseInt.map(_ |+| i).toOption) assert_=== None

foldable5.scala

nel(1, 3, 5).all(_ % 2 /== 0) assert_=== true

nel(1, 3, 6) ∀ (_ % 2 /== 0) assert_=== false

none[Int].any(_ gt 0) assert_=== false

1.some ∃ (_ gt 0) assert_=== true

List(10, 20, 30).element(30) assert_=== true

List(10, 11, 12) ∋ 13 assert_=== false

11 ∈: List(10, 11, 12) assert_=== true

foldable6.scala

nil[String].empty assert_=== true

nel(1, 2, 4).count assert_=== 3

100.some.foldIndex(0) assert_=== 100

foldable7.scala

nel(1, 2, 3).listr assert_=== List(1, 2, 3)

'Scalaz.some.listr assert_=== List('Scalaz)

"Hello".show.stream.take(3) assert_=== Stream('H', 'H', 'H')

"Hello".some.stream.take(3) assert_=== Stream("Hello")

foldable8.scala

"Scalaz".show.maximum assert_=== Some('z')

none[Int].maximum assert_=== None

nel(3, 2, 1, 2, 3).minimum assert_=== Some(1)

nil[String].minimum assert_=== None

foldable9.scala

nel(0, 1, 1, 2, 3, 5).selectSplit(_ % 2 /== 0) assert_=== List(List(1, 1), List(3, 5))

346.some.selectSplit(_ === 345) assert_=== Nil

import Digit._

11235L.digits.splitWith(_.toInt % 2 === 0) assert_=== List(List(_5, _3), List(_2), List(_1, _1))

"Scalaちゃん".show.splitWith(_ === 'a') assert_=== List(List('S', 'c'), List('a'), List('l'), List('a'), List('ち', 'ゃ', 'ん'))