;;; -*-scheme-*-

;;; Mes --- Maxwell Equations of Software
;;; Copyright © 2016 Jan Nieuwenhuizen <janneke@gnu.org>
;;;
;;; This file is part of Mes.
;;;
;;; Mes is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; Mes is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with Mes.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;;; loop-0.mes - bootstrap into Scheme from minimal -DBOOT=1 core.

;;; When compiling mes.c with -DBOOT=1, eval/apply et al. are lacking
;;; features wrt the fat-c variant, e.g., define and define-macro are
;;; not available; instead label is supplied.  Before loading
;;; boot-0.mes, loop-0.mes is loaded to provide a richer eval/apply.

;;; This might enable moving more functionality from C to Scheme,
;;; making the entirely-from-source bootstrap process more feasible.
;;; However, currently performance is 400x worse.  Also several tests
;;; in the test suite fail and the REPL does not work yet.

;;; Code:

((label loop-0
        (lambda (r e a)
          ;; (display "***LOOP-0*** ... e=") (display e) (newline)
          (if (null? e) (eval-env (cons 'begin (read-input-file-env (read-env a) a)) a)
              (if (atom? e) (loop-0 (eval-env e a) (read-env a) a)
                  (if (eq? (car e) 'define)
                      ((lambda (aa)     ; env:define
                         ;; (display "0DEFINE name=") (display (cadr e)) (newline)
                         (set-cdr! aa (cdr a))
                         (set-cdr! a aa)
                         (set-cdr! (assq '*closure* a) a)
                         (loop-0 *unspecified* (read-env a) a))
                       (cons            ; sexp:define
                        (if (atom? (cadr e)) (cons (cadr e) (eval-env (caddr e) a))
                            (cons (caadr e) (eval-env (cons 'lambda (cons (cdadr e) (cddr e))) a)))
                        '()))
                      (if (eq? (car e) 'define-macro)
                          ((lambda (name+entry) ; env:macro
                             ;; (display "0MACRO name=") (display (car name+entry)) (newline)
                             ((lambda (aa) ; env:define
                                (set-cdr! aa (cdr a))
                                (set-cdr! a aa)
                                (set-cdr! (assq '*closure* a) a)
                                (loop-0 *unspecified* (read-env a) a))
                              (cons
                               (cons (car name+entry)
                                     (make-macro (car name+entry)
                                                 (cdr name+entry)))
                               '())))
                                        ; sexp:define
                           (if (atom? (cadr e)) (cons (cadr e) (eval-env (caddr e) a))
                               (cons (caadr e) (eval-env (cons 'lambda (cons (cdadr e) (cddr e))) a)))
                           '())
                          (loop-0 (eval-env e a) (read-env a) a)))))))
 *unspecified* (read-env '()) (current-module))

()
;; enter reading loop-0
(display "loop-0 ...\n")