```common lisp
;; Declaration of package
;; Liam Healy 2009-02-22 09:55:45EST pkgdcl.lisp
;; Time-stamp: <2009-05-12 15:27:21EDT init.lisp>

(in-package :common-lisp-user)

(defpackage :foreign-structures-by-value
  (:nicknames #:fsbv)
  (:use #:common-lisp))

(cffi:load-foreign-library
 #+darwin "libffi.dylib"
 #+(and (not darwin) unix) "libffi.so")

(pushnew :fsbv *features*)
```

Add include path for OSX
user
```common lisp
;; Declaration of package
;; Liam Healy 2009-02-22 09:55:45EST pkgdcl.lisp
;; Time-stamp: <2009-08-22 16:20:00EDT init.lisp>

(in-package :common-lisp-user)

(defpackage :foreign-structures-by-value
  (:nicknames #:fsbv)
  (:use #:common-lisp))

(cffi:load-foreign-library
 #+darwin "libffi.dylib"
 #+(and (not darwin) unix) "libffi.so")

;;; When installed through Mac Ports, GSL .h files will be found
;;; in /opt/local/include.
#+darwin
(setf cffi-grovel::*cc-flags*
      (append '("-I" "/opt/local/include/") cffi-grovel::*cc-flags*))

(pushnew :fsbv *features*)
```
assistant