Import guile-1.8 as multiple upstream tarball component

[lilypond.git] / guile18 / ice-9 / and-let-star.scm

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+;;;; and-let-star.scm --- and-let* syntactic form (draft SRFI-2) for Guile
+;;;; written by Michael Livshin <mike@olan.com>
+;;;;
+;;;;   Copyright (C) 1999, 2001, 2004, 2006 Free Software Foundation, Inc.
+;;;; 
+;;;; 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 2.1 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
+
+(define-module (ice-9 and-let-star)
+  :export-syntax (and-let*))
+
+(defmacro and-let* (vars . body)
+
+  (define (expand vars body)
+    (cond
+     ((null? vars)
+      (if (null? body)
+         #t
+         `(begin ,@body)))
+     ((pair? vars)
+      (let ((exp (car vars)))
+        (cond
+         ((pair? exp)
+          (cond
+           ((null? (cdr exp))
+            `(and ,(car exp) ,(expand (cdr vars) body)))
+           (else
+            (let ((var (car exp)))
+              `(let (,exp)
+                 (and ,var ,(expand (cdr vars) body)))))))
+         (else
+          `(and ,exp ,(expand (cdr vars) body))))))
+     (else
+      (error "not a proper list" vars))))
+
+  (expand vars body))
+
+(cond-expand-provide (current-module) '(srfi-2))