;;; ;;; Time-stamp: <2008-06-19 21:13:49 noel> ;;; ;;; Copyright (C) 2005 by Noel Welsh. ;;; ;;; 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., 59 Temple ;;; Place, Suite 330, Boston, MA 02111-1307 USA ;;; Author: Noel Welsh <noelwelsh@yahoo.com> ;; ;; ;; Commentary: #lang scheme/base (require "monad.ss") (provide (all-defined-out)) (define (make-empty-hash) (make-monad (void) (make-hash))) (define (return-hash value) (lambda (hash) (set-monad-value! hash value) hash)) (define (put key val) (lambda (hash) (hash-set! (monad-state hash) key val) hash)) (define (get key) (lambda (hash) (let ((val (hash-ref (monad-state hash) key))) (set-monad-value! hash val) hash)))