This is a python package for drawing diagrams. Intended to have multiple backends, currently the only backend implemented uses cairo.

It can also include text from TeX via pdftex, pdflatex, xetex or xelatex.

Diagrams are able to be composed in various ways, based on a linear constraint solver. Therefore, this system becomes a declarative graphics layout package.

Read it online here. The documentation is distributed in huygens/doc.

This is a package for rendering string/surface diagrams for monoidal bicategories. Here are the slides from a talk at SYCO 11, and there's more demo code here.