functional_java/src/main/java/curry/CurryingExample.java at main · 66-24/functional_java · GitHub

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package curry;

import java.util.function.Function;

public class CurryingExample {

public static void main(String[] args) {

// 1. Define the curried function.

// It's a function that returns a function that returns a function.

Function<String,

Function<String, String>>> tagWrapperCurried =

prefix -> content -> suffix -> prefix + content + suffix;

// 2. Use the function by applying arguments one by one.

// Each .apply() call returns the next function in the chain.

String html = tagWrapperCurried

.apply("<h1>") // This returns a Function<String, Function<String, String>>

.apply("Hello, Currying!") // This returns a Function<String, String>

.apply("</h1>"); // This finally returns the String result

System.out.println(html); // Output: <h1>Hello, Currying!</h1>

// The real power of currying: PARTIAL APPLICATION

// You can "fix" some parameters to create more specialized functions.

// Let's create an "h1" wrapper function by fixing the first argument.

Function<String, Function<String, String>> h1Wrapper = tagWrapperCurried.apply("<h1>");

// Now we can reuse this specialized function.

String h1Title = h1Wrapper.apply("A Great Title").apply("</h1>");

System.out.println(h1Title); // Output: <h1>A Great Title</h1>

// Let's create an even more specialized function that wraps content in <h1> tags.

Function<String, String> h1ContentWrapper = h1Wrapper.apply("</h1>"); // We apply the *last* argument here

String finalContent = h1ContentWrapper.apply("Final Content");

System.out.println(finalContent); // Output: <h1>Final Content</h1>

}

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