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What is Manifold?

Manifold plugs into Java to supplement it with game-changing features, from Type-safe Metaprogramming, Structural Typing, and Extension Methods to an integrated Template Engine and a Preprocessor. All fully supported in IntelliJ IDEA. Simply add Manifold to your project and begin taking advantage of it.

What can you do with Manifold?


Use the framework to gain direct, type-safe access to any type of metadata, such as GraphQL, JSON Schema and YAML. Remove the code gen step in your build process.   Check it out!

// Use your User.json schema file directly as a type, no code gen!
User user = User.builder("myid", "mypassword", "Scott")
  .withDob(LocalDate.of(1987, 6, 15))


Add extension methods to existing Java classes, even String, List, and File. Eliminate boilerplate code.   Check it out!

String greeting = "hello";
greeting.myMethod(); // Add your own methods to String!


Use familiar directives such as #define and #if to conditionally compile your Java projects. The preprocessor offers a simple and convenient way to support multiple build targets with a single codebase.   Check it out!

  public void setTime(LocalDateTime time) {...)
  public void setTime(Calendar time) {...}

Structural Typing

Unify disparate APIs. Bridge software components you do not control. Access maps through type-safe interfaces.   Check it out!

Map<String, Object> map = new HashMap<>();
MyThingInterface thing = (MyThingInterface) map; // O_o
thing.setFoo(new Foo());
Foo foo = thing.getFoo();
out.println(thing.getClass()); // prints "java.util.HashMap"

Type-safe Reflection

Access private features with @Jailbreak to avoid the drudgery and vulnerability of Java reflection.   Check it out!

@Jailbreak Foo foo = new Foo();
// Direct, *type-safe* access to *all* foo's members
foo.privateMethod(x, y, z);
foo.privateField = value;

Checked Exception Handling

You now have an option to make checked exceptions behave like unchecked exceptions! No more unintended exception swallowing, no more boilerplate try/catch/wrap/rethrow nonsense.

List<String> strings = ...;
List<URL> urls = list
  .map(URL::new) // No need to handle the MalformedURLException!

String Templates

Embed variables and expressions in String literals, no more clunky string concat!   Check it out!

int hour = 15;
// Simple variable access with '$'
String result = "The hour is $hour"; // Yes!!!
// Use expressions with '${}'
result = "It is ${hour > 12 ? hour-12 : hour} o'clock";

Template Files with ManTL

Author template files with the full expressive power of Java, use your templates directly in your code as types. Supports type-safe inclusion of other templates, shared layouts, and more.   Check it out!

List<User> users = ...;
String content = abc.example.UserSample.render(users);

A template file abc/example/UserSample.html.mtl

<%@ import java.util.List %>
<%@ import com.example.User %>
<%@ params(List<User> users) %>
<html lang="en">
   .filter(user -> user.getDateOfBirth() != null)
   .forEach(user -> { %>
    User: ${user.getName()} <br>
    DOB: ${user.getDateOfBirth()} <br>
<% }); %>


Leverage stock Manifold extension libraries for standard Java classes. Save time and reduce boilerplate code.

File file = new File(path);
// Use refreshing extensions to File
String content = file.readText();


Use the Manifold IntelliJ IDEA plugin to fully leverage Manifold in your development cycle. The plugin provides comprehensive support for IntelliJ features including code completion, navigation, usage searching, refactoring, incremental compilation, hotswap debugging, full-featured template editing, integrated preprocessor, and more.

manifold ij plugin


The Manifold project consists of the core Manifold framework and a collection of sub-projects implementing SPIs provided by the core framework. Each project represents a separate dependency you can easily add to your project:

Manifold : Core

Manifold : GraphQL
Manifold : JSON
Manifold : YAML
Manifold : Properties
Manifold : Image
Manifold : Dark Java
Manifold : JavaScript

Manifold : Java Extension

Manifold : Templates (ManTL)

Manifold : String Interpolation
Manifold : [Un]checked Exceptions

Manifold : Preprocessor

Manifold : Collections
Manifold : I/0
Manifold : Text

Manifold : All  (Über jar)

Experiment with sample projects:

Learn More