1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
;;; ck, to facilitate applicative-order macro programming
;;; Copyright (C) 2012 Free Software Foundation, Inc
;;; Copyright (C) 2009, 2011 Oleg Kiselyov
;;;
;;; This library is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU Lesser General Public
;;; License as published by the Free Software Foundation; either
;;; version 3 of the License, or (at your option) any later version.
;;;
;;; This library 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
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this library; if not, write to the Free Software
;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;;
;;;
;;; Originally written by Oleg Kiselyov and later contributed to Guile.
;;;
;;; Based on the CK machine introduced in:
;;;
;;; Matthias Felleisen and Daniel P. Friedman: Control operators, the
;;; SECD machine, and the lambda-calculus. In Martin Wirsing, editor,
;;; Formal Description of Programming Concepts III, pages
;;; 193-217. Elsevier, Amsterdam, 1986.
;;;
;;; See http://okmij.org/ftp/Scheme/macros.html#ck-macros for details.
;;;
(define-module (system base ck)
#:export (ck))
(define-syntax ck
(syntax-rules (quote)
((ck () 'v) v) ; yield the value on empty stack
((ck (((op ...) ea ...) . s) 'v) ; re-focus on the other argument, ea
(ck-arg s (op ... 'v) ea ...))
((ck s (op ea ...)) ; Focus: handling an application;
(ck-arg s (op) ea ...)))) ; check if args are values
(define-syntax ck-arg
(syntax-rules (quote)
((ck-arg s (op va ...)) ; all arguments are evaluated,
(op s va ...)) ; do the redex
((ck-arg s (op ...) 'v ea1 ...) ; optimization when the first ea
(ck-arg s (op ... 'v) ea1 ...)) ; was already a value
((ck-arg s (op ...) ea ea1 ...) ; focus on ea, to evaluate it
(ck (((op ...) ea1 ...) . s) ea))))
|
