  option match {
    case Some(value) => value
    case None        => fallback()
  }
```
]

--


.forty-two-left[
## Def function
```scala mdoc
def greeting(): Unit =
  println("Hello")
```
]

.forty-seven-right[
## Val function
```scala mdoc:reset
val greeting: () => Unit =
  () => println("Hello")
```
]

---
# 0-parameter function

.seventy-two-left[
```scala mdoc:reset
def getOrElse[A](option: Option[A], fallback: () => A): A =
  option match {
    case Some(value) => value
    case None        => fallb