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+;;; srfi-31.scm --- special form for recursive evaluation
+
+;; Copyright (C) 2004, 2006, 2012 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 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
+
+;;; Original author: Rob Browning <rlb@defaultvalue.org>
+
+(define-module (srfi srfi-31)
+ #:export (rec))
+
+(cond-expand-provide (current-module) '(srfi-31))
+
+(define-syntax rec
+ (syntax-rules ()
+ "Return the given object, defined in a lexical environment where
+NAME is bound to itself."
+ ((_ (name . formals) body ...) ; procedure
+ (letrec ((name (lambda formals body ...)))
+ name))
+ ((_ name expr) ; arbitrary object
+ (letrec ((name expr))
+ name))))