Question: For example, there is a string val `s = "Test"`. How do you separate it into `t, e, s, t`?

Answer: 
You can use `toList` as follows:

```
scala> s.toList         
res1: List[Char] = List(T, e, s, t)

```

If you want an array, you can use `toArray`

```
scala> s.toArray
res2: Array[Char] = Array(T, e, s, t)

```
Additionally, it should be noted that if what you actually want isn't an actual list object, but simply to do something which each character, then Strings can be used as iterable collections of characters in Scala

```
for(ch<-"Test") println("_" + ch + "_") //prints each letter on a different line, surrounded by underscores

```