CFFI, the Common Foreign Function Interface, purports to be a portable foreign
function interface for Common Lisp. The CFFI library is composed of a
Lisp-implementation-specific backend in the CFFI-SYS package, and a portable
frontend in the CFFI package.

Some of the key features include:
  - an extensible foreign type system;
  - callback support;
  - support for foreign string encodings;
  - ported to Allegro CL, Corman CL, CLISP, CMUCL, ECL, LispWorks, Clozure CL,
    SBCL and the Scieneer CL;
  - a groveller;
  - a UFFI compatibility layer.