SeExpr is simple expression language that provided artistic control and
customization to your software.  It can be used for procedural geometry
synthesis, image synthesis, simulation control, and much more.

Major features:

  * Arithmetic expression of scalar/vector types
  * Large library of built-in functions
  * Extensible variables and functions (including with DSOs)
  * Simple to embed in any program
  * High-level UI components to manipulate and visualize expressions

WWW: http://www.disneyanimation.com/technology/seexpr.html