Clean
   The Software Technology Research Group develops this pure, lazy functional programming language, with hybrid static/dynamic typing, and Integrated Development Environment (IDE) with syntax coloring editor; descriptions, papers, software downloads.
   http://clean.cs.ru.nl/

Clean Game Library
   Full development system for 2D games: arcade, side scrollers, platform games.
   http://cleangl.sourceforge.net/

Sparkle
   Clean theorem prover, can help prove partial correctness of programs, or useful traits of parts of programs; proof process uses hint mechanism, suggests proof actions to user; windowing user interface shows content graphically in windows that can be resiz
   http://www.cs.ru.nl/Sparkle/

The Game of Life
   Life: A Clean Programming Tutorial and Case Study. Tutorial for this functional language, in the form of a stepwise development of 2 programs to animate Conway's Game of Life.
   http://members.ozemail.com.au/~dekker/life/LIFE.HTML

Wikipedia: Clean Programming Language
   Encyclopedia article, with links to many related topics.
   http://en.wikipedia.org/wiki/Clean_(programming_language)