---
title: "Comment by sammo90 on \"Traversing Cats Effect IOs [Part-3]\" | Hashnode"
description: "def example6 = val io1 = IO(\"Scala6\") val io2 = IO(\"Cats6\") val listTraverse = Traverse[List] // a typeclass instance -> import cats.implicits.toTraverseOps"
url: "https://hashnode.com/posts/traversing-cats-effect-ios-part-3/62715202d64dcf11c4fb584f/comment/6a02e240937b84f77943a0b9"
---

[Discussion](https://hashnode.com/posts/traversing-cats-effect-ios-part-3/62715202d64dcf11c4fb584f)

Comment [Traversing Cats Effect IOs \[Part-3\]](https://hashnode.com/posts/traversing-cats-effect-ios-part-3/62715202d64dcf11c4fb584f)

[sammo90](https://hashnode.com/@sammo90)

[May 12](https://hashnode.com/posts/traversing-cats-effect-ios-part-3/62715202d64dcf11c4fb584f/comment/6a02e240937b84f77943a0b9)

```
def example6 =
  val io1 = IO("Scala6")
  val io2 = IO("Cats6")
  val listTraverse = Traverse[List] // a typeclass instance  -> import cats.implicits.toTraverseOps
  
  val ioList: List[IO[String]] = List(io1, io2)
  val insideOutIOs: IO[List[String]] = listTraverse.sequence(ioList)

  // is equal to the sequence-method:
  // val seqAsTraverse: IO[List[String]] = listTraverse.traverse(ioList)(identity)

  val traversedList: IO[List[String]] = listTraverse.traverse(ioList)(io => io.map(_ + "!"))
  traversedList.trace
```

Due to the import, no typeclass instance is needed anymore!

```
def example7 =
  import cats.implicits.toTraverseOps
    
  val io1 = IO("Scala7")
  val io2 = IO("Cats7")
  
  val ioList: List[IO[String]] = List(io1, io2)
  val insideOutIOs: IO[List[String]] = ioList.sequence

  val traversedList: IO[List[String]] = ioList.traverse(io => io.map(_ + "!"))
  traversedList.trace
```

[Yadukrishnan](https://hashnode.com/@yadukrishnan)

[May 15](https://hashnode.com/posts/traversing-cats-effect-ios-part-3/62715202d64dcf11c4fb584f/comment/6a02e240937b84f77943a0b9#reply-6a0734c873afc887577abba1)

Thanks, i updated the article.