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adamc@5
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1 (* Copyright (c) 2008, Adam Chlipala
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2 * All rights reserved.
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3 *
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4 * Redistribution and use in source and binary forms, with or without
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5 * modification, are permitted provided that the following conditions are met:
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6 *
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7 * - Redistributions of source code must retain the above copyright notice,
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8 * this list of conditions and the following disclaimer.
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9 * - Redistributions in binary form must reproduce the above copyright notice,
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10 * this list of conditions and the following disclaimer in the documentation
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11 * and/or other materials provided with the distribution.
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12 * - The names of contributors may not be used to endorse or promote products
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13 * derived from this software without specific prior written permission.
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14 *
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15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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18 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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19 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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20 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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21 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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23 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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24 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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25 * POSSIBILITY OF SUCH DAMAGE.
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26 *)
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27
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28 structure ListUtil :> LIST_UTIL = struct
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29
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30 fun mapfoldl f i =
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31 let
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32 fun mf s ls' ls =
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33 case ls of
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34 nil => (s, rev ls')
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35 | h :: t =>
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36 let
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37 val (s, h') = f (h, s)
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38 in
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39 mf s (h' :: ls') t
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40 end
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41 in
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42 mf i []
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43 end
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44
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45 structure S = Search
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46
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47 fun mapfold f =
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48 let
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49 fun mf ls s =
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50 case ls of
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51 nil => S.Continue (nil, s)
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52 | h :: t =>
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53 case f h s of
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54 S.Return x => S.Return x
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55 | S.Continue (h', s) =>
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56 case mf t s of
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57 S.Return x => S.Return x
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58 | S.Continue (t', s) => S.Continue (h' :: t', s)
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59 in
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60 mf
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61 end
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62
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63 fun search f =
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64 let
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65 fun s ls =
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66 case ls of
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67 [] => NONE
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68 | h :: t =>
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69 case f h of
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70 NONE => s t
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71 | v => v
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72 in
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73 s
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74 end
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75
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76 end
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