Simple chaining validation example with pure Scala

FoldingValidationExamples.scala

import scala.util.{Failure, Try}

val li=List(1,2,3,4)

type Transform[F[_],A]=F[A] => F[A]

def filterSmall: Transform[Try,Int] ={ ti=>
  ti.flatMap(i=>if (i>1) Try(i) else new Failure(new Exception(s"$i is too small")))
}

def double: Transform[Try,Int] = _.map(_ * 2)

def add10: Transform[Try,Int] = _.map(_ + 10)

val functions=List(filterSmall, double, add10)

def machine(i:Int)=functions.foldLeft(Try(i)){(tryInt,func)=>func(tryInt)}

val work=li.map(machine)

work.map(_.toString)

def add11: Transform[Option,Int] = _.map(_ + 11)

def triple: Transform[Option,Int] = _.map(_ * 3)

val functions2=List(add11, triple)

def machine2(i:Int)=functions2.foldLeft(Option(i)){(optionInt,func)=>func(optionInt)}

li.map(machine2)

output.txt

work: List[scala.util.Try[Int]] = List(Failure(java.lang.Exception: 1 is too small), Success(14), Success(16), Success(18))

res1: List[Option[Int]] = List(Some(36), Some(39), Some(42), Some(45))