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Pure Functional Programming Semantics For Java

There is a newer version: 0.3.1

/**
 * Copyright (c) Rich Hickey. All rights reserved.
 * The use and distribution terms for this software are covered by the
 * Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
 * which can be found in the file epl-v10.html at the root of this distribution.
 * By using this software in any fashion, you are agreeing to be bound by
 * the terms of this license.
 * You must not remove this notice, or any other, from this software.
 */

package org.pure4j.collections;

import org.pure4j.annotations.immutable.ImmutableValue;


/**
 * A persistent, functional, sequence interface.
 * 
 * ISeqs are immutable values, i.e. neither first(), nor rest() changes or
 * invalidates the ISeq.
 * 
 * 
This is the equivalent of java.util.Iterator for persistent collections.
 * 
 * An empty seq is null.  
 */
@ImmutableValue
public interface ISeq extends Counted, Seqable {

	K first();

	/**
	 * @return a seq for the remainder of the list. If there are no more elements, returns null.
	 */
	ISeq next();

	ISeq more();

	/**
	 * Adds an element to the front of the seq.
	 * @return A new non-null ISeq.
	 * @param o any object
	 */
	ISeq cons(K o);

}