CLAUDE (the Common Lisp Library Audience Expansion Toolkit) exports libraries written in Common Lisp, so that applications being developed in other languages can access them. CLAUDE co-operates with foreign runtimes in the management of CLOS objects, records, arrays and more primitive types. Lisp macros make the task of exporting a library simple and elegant; template documentation along with C headers and sample code files relieve some of the burden of explaining such exports to the application programmer.

http://www.nicklevine.org/claude/