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What is Manifold?

Manifold re-energizes Java with powerful features like Type-safe Metaprogramming, Structural Typing, and Extension Methods.
Simply add the Manifold jar 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.

// 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!

Structural Typing

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

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.

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

Checked Exception Suppression

Simply add the exceptions plugin argument: -Xplugin:Manifold stringsexceptions. Now checked exceptions
behave like unchecked exceptions! No more compiler errors, no more boilerplate try/catch nonsense.

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

String Templates (aka String Interpolation)

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

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.

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

A tempate 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, and more.

Learn More


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