60 lines
2.4 KiB
Scheme
60 lines
2.4 KiB
Scheme
;;; -*-scheme-*-
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;;; GNU Mes --- Maxwell Equations of Software
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;;; Copyright © 2016,2017 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
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;;;
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;;; This file is part of GNU Mes.
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;;;
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;;; GNU Mes is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Mes is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Mes. If not, see <http://www.gnu.org/licenses/>.
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;;; Commentary:
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;;; quasiquote.mes is loaded after base. It provides quasiquote
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;;; written in Scheme.
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;;; Code:
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(mes-use-module (mes base))
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(define (quasiquote-expand x)
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(cond ((vector? x) (list 'list->vector (quasiquote-expand (vector->list x))))
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((not (pair? x)) (cons 'quote (cons x '())))
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((eq? (car x) 'quasiquote) (quasiquote-expand (quasiquote-expand
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(if (null? (cddr x)) (cadr x)
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(cons 'list (cdr x))))))
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((eq? (car x) 'unquote) (if (null? (cddr x)) (cadr x)
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(cons 'list (cdr x))))
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((and (pair? (car x)) (eq? (caar x) 'unquote-splicing))
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((lambda (d)
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(if (null? (cddar x)) (list 'append (cadar x) d)
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(list 'quote (append (cdar x) d))))
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(quasiquote-expand (cdr x))))
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(else ((lambda (a d)
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(if (pair? d)
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(if (eq? (car d) 'quote)
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(if (and (pair? a) (eq? (car a) 'quote))
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(list 'quote (cons (cadr a) (cadr d)))
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(if (null? (cadr d))
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(list 'list a)
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(list 'cons* a d)))
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(if (memq (car d) '(list cons*))
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(cons (car d) (cons a (cdr d)))
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(list 'cons* a d)))
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(list 'cons* a d)))
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(quasiquote-expand (car x))
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(quasiquote-expand (cdr x))))))
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(define-macro (quasiquote x)
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(quasiquote-expand x))
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