Nell is a language for describing two dimensional vector drawings. We have been using versions of the language for several years to create illustrations for books, webpages and various art projects. It can even be used as a tool for physics and math simulations and experiments.
We created the language because of our frustration with how tedious and time consuming it can be to create complex vector drawings. Why sit in front of a screen for hours clicking and dragging with a mouse when you can spend a few minutes thinking about your drawing, solving a few geometry and trigonometry problems and then writing a simple program that will create the drawing for you? It's less tedious and a lot more fun, plus you get to sharpen your math and programming skills.
The book comes with software that translates a drawing definition in the Nell language into an SVG file. The software is free and open source with a GPL license. It can be downloaded from the book's website at http://www.abrazol.com/books/nell/
A pdf book "Nell: An SVG Drawing Language"