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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 structure S = Search
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31
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32 fun mapfold f =
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33 let
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34 fun mf ls s =
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35 case ls of
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36 nil => S.Continue (nil, s)
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37 | h :: t =>
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38 case f h s of
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39 S.Return x => S.Return x
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40 | S.Continue (h', s) =>
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41 case mf t s of
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42 S.Return x => S.Return x
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43 | S.Continue (t', s) => S.Continue (h' :: t', s)
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44 in
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45 mf
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46 end
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47
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48 fun mapfoldB f =
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49 let
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50 fun mf ctx ls s =
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51 case ls of
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52 nil => S.Continue (nil, s)
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53 | h :: t =>
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54 let
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55 val (ctx, r) = f (ctx, h)
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56 in
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57 case r s of
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58 S.Return x => S.Return x
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59 | S.Continue (h', s) =>
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60 case mf ctx t s of
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61 S.Return x => S.Return x
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62 | S.Continue (t', s) => S.Continue (h' :: t', s)
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63 end
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64 in
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65 mf
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66 end
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67
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68 fun foldlMap f s =
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69 let
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70 fun fm (ls', s) ls =
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71 case ls of
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72 nil => (rev ls', s)
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73 | h :: t =>
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74 let
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75 val (h', s') = f (h, s)
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76 in
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77 fm (h' :: ls', s') t
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78 end
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79 in
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80 fm ([], s)
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81 end
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82
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83 fun search f =
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84 let
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85 fun s ls =
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86 case ls of
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87 [] => NONE
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88 | h :: t =>
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89 case f h of
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90 NONE => s t
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91 | v => v
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92 in
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93 s
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94 end
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95
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96 end
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