Currying Functions in Java with Examples

Function Currying is a concept of breaking a function with many arguments into many functions with single argument in such a way, that the output is same. In other words, its a technique of simplifying a multi-valued argument function into single-valued argument multi-functions.

Consider the example to clear the concept:

Currying breaks down higher order functions into a series of smaller cascaded functions which take in one argument and return a function except for the last cascaded function which returns the desired value.

For example:

Let there be a function which maps as

Currying the above function will produce

Thus maps from to a function which in turn maps from to
The above mathematical expression can also be represented as:

Hence,

Below are some examples in Java to demonstrate Function Currying:

Example 1: Adding 2 numbers using Function Currying

// Java Program to demonstrate Function Currying

import java.util.function.Function;

public class GFG {
    public static void main(String args[])
    {

        // Using Java 8 Functions
        // to create lambda expressions for functions
        // and with this, applying Function Currying

        // Curried Function for Adding u & v
        Function<Integer,
                 Function<Integer, Integer> >
            curryAdder = u -> v -> u + v;

        // Calling the curried functions

        // Calling Curried Function for Adding u & v
        System.out.println("Add 2, 3 :"
                           + curryAdder
                                 .apply(2)
                                 .apply(3));

        }
}

Output:

Add 2, 3 :5

Example 2: Multiplying 2 numbers using Function Currying

// Java Program to demonstrate Function Currying

import java.util.function.Function;

public class GFG {
    public static void main(String args[])
    {

        // Using Java 8 Functions
        // to create lambda expressions for functions
        // and with this, applying Function Currying

        // Curried Function for Multiplying u & v
        Function<Integer,
                 Function<Integer, Integer> >
            curryMulti = u -> v -> u * v;

        // Calling the curried functions

        // Calling Curried Function for Multiplying u & v
        System.out.println("Multiply 2, 3 :"
                           + curryMulti
                                 .apply(2)
                                 .apply(3));
    }
}

Output:

Multiply 2, 3 :6

Example 3: Adding 3 numbers using Function Currying

// Java Program to demonstrate Function Currying

import java.util.function.Function;

public class GFG {
    public static void main(String args[])
    {

        // Using Java 8 Functions
        // to create lambda expressions for functions
        // and with this, applying Function Currying

        // Curried Function for Adding u, v & w
        Function<Integer,
                 Function<Integer,
                          Function<Integer, Integer> > >
            triadder = u -> w -> v -> u + w + v;

        // Calling the curried functions

        // Calling Curried Function for Adding u, v & w
        System.out.println("Add 2, 3, 4 :"
                           + triadder
                                 .apply(2)
                                 .apply(3)
                                 .apply(4));
    }
}

Output:

Add 2, 3, 4 :9