A demonstration in Scala of failed associativity of ListT. Example taken from https://wiki.haskell.org/ListT_done_right

// addCompilerPlugin("com.milessabin" % "si2712fix-plugin" % "1.2.0" cross CrossVersion.full) import scalaz., Scalaz.

implicit def f2k[F[_], A, B](f: A => F[B]) = Kleisli(f)

val a: Int => ListT[List, Int] = { case 0 => ListT(List(List(0, 1))) case 1 => ListT(List(List(0), List(1))) }

println(((a >=> a) >=> a ).run(0)) println(( a >=> (a >=> a)).run(0))

// ListT(List(List(0, 1, 0, 0, 1), List(0, 1, 1, 0, 1), List(0, 1, 0, 0), List(0, 1, 0, 1), List(0, 1, 1, 0), List(0, 1, 1, 1))) // ListT(List(List(0, 1, 0, 0, 1), List(0, 1, 0, 0), List(0, 1, 0, 1), List(0, 1, 1, 0, 1), List(0, 1, 1, 0), List(0, 1, 1, 1)))