https://github.com/eclipse/eclipse-collections/eclipse-collections-api: Eclipse Collections is a collections framework for Java. It has JDK-compatible List, Set and Map implementations with a rich API and set of utility classes that work with any JDK compatible Collections, Arrays, Maps or Strings. The iteration protocol was inspired by the Smalltalk collection framework.
  • Craig P. Motlin
  • Donald Raab
  • Mohammad A. Rezaei
  • Hiroshi Ito
  • Nikhil J. Nanivadekar 
/*
 * Copyright (c) 2018 Goldman Sachs.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v. 1.0 which accompany this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 */

package org.eclipse.collections.api.block.function;

import java.io.Serializable;


Function is a one-argument lambda which performs a transformation on the object of type T passed to the valueOf() method. This transformation can return the value of calling a getter, or perform some more elaborate logic to calculate a value, of type V. 
/**
 * Function is a one-argument lambda which performs a transformation on the object of type {@code T}
 * passed to the valueOf() method. This transformation can return the value of calling a getter, or perform
 * some more elaborate logic to calculate a value, of type {@code V}.
 */
@FunctionalInterface
public interface Function<T, V>
        extends java.util.function.Function<T, V>, Serializable
{
    V valueOf(T each);

    @Override
    default V apply(T each)
    {
        return this.valueOf(each);
    }
}