Currying in Scala

Currying is one of the several mechanisms in Scala to create control abstractions.

Common way of writing function is as:

def plainCommonSum(x: Int, y: Int) = x + y

This function has a single parameter list.

A curried function, on other hand, is applied to multiple argument lists. Above function when written in 'curried' manner:

def curriedSum(x: Int)(y: Int) = x + y

An invocation to a curried function is basically a sequence of traditional function invocations.For example, when we call 'curriedSum' ,first a function call takes a single Int parameter 'x', and returns a function value. A second function call is made with this function value and it takes a single Int parameter 'y',and returns an Int.

We can get reference to 'second' function by using placeholder notation.

def greetSomeOne(greeting: String)(name: String) =  greeting + " " +name

val greetHi = greetSomeOne("Hi")_ 

val greetHello = greetSomeOne("Hello")_

       println(greetHi("World"))

println(greetHello("World")) 

Output is:

Hi World

Hello World