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1 | ;;;; and-let-star.scm --- and-let* syntactic form (draft SRFI-2) for Guile |
2 | ;;;; written by Michael Livshin <mike@olan.com> | |
3 | ;;;; | |
e39bbe80 | 4 | ;;;; Copyright (C) 1999, 2001 Free Software Foundation, Inc. |
93a6e9c4 | 5 | ;;;; |
73be1d9e MV |
6 | ;;;; This library is free software; you can redistribute it and/or |
7 | ;;;; modify it under the terms of the GNU Lesser General Public | |
8 | ;;;; License as published by the Free Software Foundation; either | |
9 | ;;;; version 2.1 of the License, or (at your option) any later version. | |
93a6e9c4 | 10 | ;;;; |
73be1d9e | 11 | ;;;; This library is distributed in the hope that it will be useful, |
93a6e9c4 | 12 | ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of |
73be1d9e MV |
13 | ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
14 | ;;;; Lesser General Public License for more details. | |
93a6e9c4 | 15 | ;;;; |
73be1d9e MV |
16 | ;;;; You should have received a copy of the GNU Lesser General Public |
17 | ;;;; License along with this library; if not, write to the Free Software | |
18 | ;;;; Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
93a6e9c4 | 19 | |
1a179b03 MD |
20 | (define-module (ice-9 and-let-star) |
21 | :export-syntax (and-let*)) | |
93a6e9c4 MV |
22 | |
23 | (defmacro and-let* (vars . body) | |
24 | ||
25 | (define (expand vars body) | |
26 | (cond | |
27 | ((null? vars) | |
28 | `(begin ,@body)) | |
29 | ((pair? vars) | |
30 | (let ((exp (car vars))) | |
31 | (cond | |
32 | ((pair? exp) | |
33 | (cond | |
34 | ((null? (cdr exp)) | |
35 | `(and ,(car exp) ,(expand (cdr vars) body))) | |
36 | (else | |
37 | (let ((var (car exp)) | |
38 | (val (cadr exp))) | |
39 | `(let (,exp) | |
40 | (and ,var ,(expand (cdr vars) body))))))) | |
41 | (else | |
42 | `(and ,exp ,(expand (cdr vars) body)))))) | |
43 | (else | |
44 | (error "not a proper list" vars)))) | |
45 | ||
46 | (expand vars body)) |