Consider a simple task: buying a coffee. In a standard imperative style, you might have a side effect where the credit card is charged immediately. In a functional style, you return the charge as a to be processed later. Impure Code (Side Effect):
: In Scala, functions are first-class citizens. You can pass them as arguments to other functions (like map , filter , or flatmap ) or return them as values. Functional Programming in Scala
To write functional Scala, you need to master three fundamental concepts: Consider a simple task: buying a coffee