FP - sequence :: Seq[Try[T]] to Try[Seq[T]]

sequence.scala

import scala.util.{Try,Success,Failure}

def sequence[T](seq: Seq[Try[T]]): Try[Seq[T]] =
  seq
    .foldRight(Try(List.empty[T])) {
      case (item, acc) => for { a <- acc; i<- item } yield i :: a
    }

import scala.util.{Try,Success,Failure}

val tf = Seq(Success(1), Success(2), Failure(new RuntimeException("not a number")), Success(4), Success(5))
val ts = Seq(Success(1), Success(2), Success(3), Success(4), Success(5))

val rf = sequence(tf)
val rs = sequence(ts)

Prints:

rf: scala.util.Try[Seq[Int]] = Failure((java.lang.RuntimeException: not a number)
rs: scala.util.Try[Seq[Int]] = Success(List(1, 2, 3, 4, 5))