Mastering Functional Programming

If and While

if and while are implemented the same way as they are in any other programming language:

scala> val flag = trueflag: Boolean = truescala> if (flag) {     | println("Flag is true")     | }Flag is truescala> if (!flag) {     | println("Flag is false")     | } else {     | println("Flag is true")     | }Flag is truescala> var x: Int = 0x: Int = 0scala> while (x < 5) {     | x += 1     | println(s"x = $x")     | }x = 1x = 2x = 3x = 4x = 5

Notice that in such constructs, you can optionally omit the curly braces if the body of the construct is a single expression:

scala> if (flag) println("Flag is true")Flag is true

This is something you can do in many places in Scala. Wherever you have a body that consists of a single expression, you can omit the curly braces around ...