Higher-order FunctionsHigher-order Functions
Scala allows the definition of higher-order functions. These are functions that take other functions as parameters, or whose result is a function. Here is a function apply which takes another function f and a value v and applies function f to v:
Note: methods are automatically coerced to functions if the context requires this.
def apply(f: Int => String, v: Int) = f(v)
Read more: Scala documentation