Couple of things: * Is there any reason you are not using the open-cv library that exists for common lisp? https://github.com/ryepup/cl-opencv. It is 3 years old but reading the code may help you work out some of the answers. * What is the error message in *inferior-lisp*? Normally unless you have manged to corrupt the lisp image somewhere (which you can do with cffi, I certainly have plenty of times) an error in the foreign function shouldnt crash lisp. Looking forward to the error message! On 15 October 2013 23:16, Joeish W <joeish80829@yahoo.com> wrote:

I wrapped opencv's cvError like this

;; void cvError(int status, const char* func_name, const char* err_msg, const char* file_name, int line) (cffi:defcfun ("cvError" cv-error) :void (status :int) (func-name :string) (err-msg :string) (file-name :string) (line :int))

but the whole purpose of the function is to cause an error in c which it does perfectly when i run this at the repl

(cv-error +stsoutofrange+ "SCALAR" "error" "/home/w/Documents/opencv-2.4.6.1/modules/calib3d/src/epnp.cpp" 1)

here is the error

OpenCV Error: One of arguments' values is out of range (bew!) in SCALAR, file /home/w/Documents/opencv-2.4.6.1/modules/calib3d/src/epnp.cpp, line 1 terminate called after throwing an instance of 'cv::Exception'

but the thing is it causes the error in c on the inferior-lisp buffer in emacs on the repl buffer the repl just hangs....how would i go about getting this error(above) to show up on the lisp side