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
$f:(u, v) -> w$

Currying the above function will produce
$g:(u->(v->w))$

Thus $g$ maps from $u$ to a function which in turn maps from $v$ to $w$
The above mathematical expression can also be represented as:
${g(u)}(v)=f(u, v)$

Hence, $curry(f) = g$

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

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