adamc@5: (* Copyright (c) 2008, Adam Chlipala
adamc@5:  * All rights reserved.
adamc@5:  *
adamc@5:  * Redistribution and use in source and binary forms, with or without
adamc@5:  * modification, are permitted provided that the following conditions are met:
adamc@5:  *
adamc@5:  * - Redistributions of source code must retain the above copyright notice,
adamc@5:  *   this list of conditions and the following disclaimer.
adamc@5:  * - Redistributions in binary form must reproduce the above copyright notice,
adamc@5:  *   this list of conditions and the following disclaimer in the documentation
adamc@5:  *   and/or other materials provided with the distribution.
adamc@5:  * - The names of contributors may not be used to endorse or promote products
adamc@5:  *   derived from this software without specific prior written permission.
adamc@5:  *
adamc@5:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
adamc@5:  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
adamc@5:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
adamc@5:  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
adamc@5:  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
adamc@5:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
adamc@5:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
adamc@5:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
adamc@5:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
adamc@5:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
adamc@5:  * POSSIBILITY OF SUCH DAMAGE.
adamc@5:  *)
adamc@5: 
adamc@5: structure ListUtil :> LIST_UTIL = struct
adamc@5: 
adamc@5: fun mapfoldl f i =
adamc@5:     let
adamc@5:         fun mf s ls' ls =
adamc@5:             case ls of
adamc@5:                 nil => (s, rev ls')
adamc@5:               | h :: t =>
adamc@5:                 let
adamc@5:                     val (s, h') = f (h, s)
adamc@5:                 in
adamc@5:                     mf s (h' :: ls') t
adamc@5:                 end
adamc@5:     in
adamc@5:         mf i []
adamc@5:     end
adamc@5: 
adamc@5: end