1 Introduction

CFFI is the Common Foreign Function Interface for ANSI Common Lisp systems. By foreign function we mean a function written in another programming language and having different data and calling conventions than Common Lisp, namely, C. CFFI allows you to call foreign functions and access foreign variables, all without leaving the Lisp image.

We consider this manual ever a work in progress. If you have difficulty with anything CFFI-specific presented in the manual, please contact the developers with details.

Motivation

See What makes Lisp different, for an argument in favor of FFI in general.

CFFI’s primary role in any image is to mediate between Lisp developers and the widely varying FFIs present in the various Lisp implementations it supports. With CFFI, you can define foreign function interfaces while still maintaining portability between implementations. It is not the first Common Lisp package with this objective; however, it is meant to be a more malleable framework than similar packages.

Design Philosophy

• Pointers do not carry around type information. Instead, type information is supplied when pointers are dereferenced.
• A type safe pointer interface can be developed on top of an untyped one. It is difficult to do the opposite.
• Functions are better than macros. When a macro could be used for performance, use a compiler-macro instead.