Elisp Embedded Scryer (alpha!)

[jjtolton]

Having fun embedding Scryer Prolog in emacs!

(add-to-list 'load-path "~/.emacs.d/vendor/emacs-ffi")
;; Assume you have a dynamic module or an external FFI library to handle it
(require 'ffi) ;; Ensure proper ffi module is loaded

(define-ffi-library libscryer_prolog.so "/home/jay/programs/scryer-prolog/target/release/libscryer_prolog")

(define-ffi-function scryer-machine-new "scryer_machine_new" :pointer nil libscryer_prolog.so)

(define-ffi-function scryer-machine-free "scryer_machine_free" :void (:pointer) libscryer_prolog.so)

(define-ffi-function scryer-run-query-iter "scryer_run_query_iter" :pointer (:pointer :pointer) libscryer_prolog.so)

(define-ffi-function scryer-query-state-free "scryer_query_state_free" :void (:pointer) libscryer_prolog.so)

(define-ffi-function scryer-run-query-next "scryer_run_query_next" :pointer (:pointer) libscryer_prolog.so)

(define-ffi-function scryer-consult-module-string "scryer_consult_module_string" :void (:pointer :pointer :pointer) libscryer_prolog.so)

(define-ffi-function scryer-run-query "scryer_run_query" :pointer (:pointer :pointer) libscryer_prolog.so)

(define-ffi-function scryer-free-c-string "scryer_free_c_string" :void (:pointer) libscryer_prolog.so)

(comment
 
 (setq wam (scryer-machine-new))

 (with-ffi-strings ((foo "foo")
                    (module ":- use_module(library(clpz))."))
   (scryer-consult-module-string wam  foo module))

 (ffi-get-c-string
  (with-ffi-string (query "1 + 2 #= 3.")
    (scryer-run-query wam query))) ;;=> "{\"result\":true,\"status\":\"ok\"}"
 
 (let ((wam (scryer-machine-new)))
   (unwind-protect 
       (let ((p  (with-ffi-string (query "use_module(library(lists)), member(X, [1, 2, 3]).")
                   (scryer-run-query wam query))))
         (unwind-protect (ffi-get-c-string p)
           (ffi-free p)))
     (scryer-machine-free wam))) ;;=> "{\"result\":[{\"bindings\":{\"X\":1}},{\"bindings\":{\"X\":2}},{\"bindings\":{\"X\":3}}],\"status\":\"ok\"}"
 
 )

Using the forked emacs package emacs-ffi and this branch of the embedded work: jjtolton@8b307a1

I'm surprised at how well it's working!