Functional Programming - Currying

Currying is a technique where a many arguments function call is replaced with multiple method calls with lesser arguments.

See the below equation.

(1 + 2 + 3) = 1 + (2 + 3) = 1 + 5 = 6

In terms of functions:

f(1,2,3) = g(1) + h(2 + 3) = 1 + 5 = 6

This cascading of functions is called currying and calls to cascaded functions must gives the same result as by calling the main function.

Example - Usage of Currying

Following example shows how Currying works.

FunctionTester.java

package com.tutorialspoint;

import java.util.function.Function;

public class FunctionTester {
   public static void main(String[] args) {
      Function<Integer, Function<Integer, Function<Integer, Integer>>> 
         addNumbers = u -> v -> w -> u + v + w;             
      int result = addNumbers.apply(2).apply(3).apply(4);        
      System.out.println(result);
   } 
}

Output

Run the FunctionTester and verify the output.

9