JOpticle

Implementation of functional lenses in Java. Contains imlementation that uses Java bean properies to reflect the get and set methods for a specific field.

Creating and using BeanLens

class Address {
  private String zipCode;
  public String getZipCode() {return zipCode;}
  public void setZipCode(String zipCode) {this.zipCode = zipCode;}
}

class Person {
  private Address address;
  public Address getAddress() {return address;}
  public void setAddress(Address address) {this.address = address;}
}

...

Lens<Person, Address> addressLens = new BeanLens<Person, Address>("address", Person.class);
Lens<Address, String> zipCodeLens = new BeanLens<Address, String>("zipCode", Address.class);

// Lenses can compose
Lens<Person, String> composedLens = addressLens.andThen(zipCodeLens);

Person p = addressLens.set(new Person(), zipCodeLens.set(new Address(), "123456"));

String zipCode = composedLens.get(p); //"123456"

The BeanLens will modify the field of the given source and return it.

The BeanDeepCopyLens will copy the source, modity the field of the copy and return the copy. The source will remain unchanged.

Creating FunctionalLens

import static org.jopticle.lenses.FunctionalLens.lens;
import fj.F;
import fj.F2;

...

Lens<Person, Address> addressLens = lens(new F<Person, Address>() {
  		@Override
			public Address f(Person arg0) {
				return arg0.getAddress();
			}
		}, new F2<Person, Address, Person>() {

			@Override
			public Person f(Person arg0, Address arg1) {
				Person p = new Person();
				p.setAddress(arg1);
				return p;
			}
		});

Lens<Address, String> zipCodeLens = lens(new F<Address, String>() {
			@Override
			public String f(Address arg0) {
				return arg0.getZipCode();
			}
		}, new F2<Address, String, Address>() {

			@Override
			public Address f(Address arg0, String arg1) {
				Address address = new Address();
				address.setZipCode(arg1);
				return address;
			}
		});