module/srfi/srfi-31.scm

   1 ;;; srfi-31.scm --- special form for recursive evaluation
   2
   3 ;;      Copyright (C) 2004, 2006, 2012 Free Software Foundation, Inc.
   4 ;;
   5 ;; This library is free software; you can redistribute it and/or
   6 ;; modify it under the terms of the GNU Lesser General Public
   7 ;; License as published by the Free Software Foundation; either
   8 ;; version 3 of the License, or (at your option) any later version.
   9 ;;
  10 ;; This library is distributed in the hope that it will be useful,
  11 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 ;; Lesser General Public License for more details.
  14 ;;
  15 ;; You should have received a copy of the GNU Lesser General Public
  16 ;; License along with this library; if not, write to the Free Software
  17 ;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18
  19 ;;; Original author: Rob Browning <rlb@defaultvalue.org>
  20
  21 (define-module (srfi srfi-31)
  22   #:export (rec))
  23
  24 (cond-expand-provide (current-module) '(srfi-31))
  25
  26 (define-syntax rec
  27   (syntax-rules ()
  28     "Return the given object, defined in a lexical environment where
  29 NAME is bound to itself."
  30     ((_ (name . formals) body ...)                ; procedure
  31      (letrec ((name (lambda formals body ...)))
  32        name))
  33     ((_ name expr)                                ; arbitrary object
  34      (letrec ((name expr))
  35        name))))