;;; cl-scopes/forge - may the forge be with you!

;;;; A Forth-like interpreter implemented in Common Lisp.

(defpackage :scopes/forge
  (:use :common-lisp)
  (:export #:forge-env #:data-stack #:exec))

(in-package :scopes/forge)

(defvar *builtins* (make-hash-table :test 'equalp))

(defclass forge-env ()
  ((data-stack :initform nil
			   :reader data-stack
			   :accessor data-stack!)))

(defun forge-env ()
  (make-instance 'forge-env))

(defun exec (fe code)
  (dolist (x code)
	(if (symbolp x)
      (funcall (gethash (string-downcase (symbol-name x)) *builtins*) fe)
	  (pushd fe x))))

(defun register (voc key fn)
  (setf (gethash (string-downcase (symbol-name key)) voc) fn))

; built-in primitives

(defun reg-b (key fn) (register *builtins* key fn))

(reg-b 'add #'(lambda (fe) (pushd fe (+ (popd fe) (popd fe)))))

; internal definitions

(defun popd (fe)
  (pop (data-stack! fe)))

(defun pushd (fe v)
  (push v (data-stack! fe)))