summaryrefslogtreecommitdiff
path: root/src/list_util.sml
blob: 976e47080f2d079d4228a5d208a738e4d2f88b7c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
(* Copyright (c) 2008, Adam Chlipala
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - The names of contributors may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *)

structure ListUtil :> LIST_UTIL = struct

structure S = Search

fun mapConcat f =
    let
        fun mc acc ls =
            case ls of
                [] => rev acc
              | h :: t => mc (List.revAppend (f h, acc)) t
    in
        mc []
    end

fun mapfold f =
    let
        fun mf ls s =
            case ls of
                nil => S.Continue (nil, s)
              | h :: t =>
                case f h s of
                    S.Return x => S.Return x
                  | S.Continue (h', s) =>
                    case mf t s of
                        S.Return x => S.Return x
                      | S.Continue (t', s) => S.Continue (h' :: t', s)
    in
        mf
    end

fun mapfoldB f =
    let
        fun mf ctx ls s =
            case ls of
                nil => S.Continue (nil, s)
              | h :: t =>
                let
                    val (ctx, r) = f (ctx, h)
                in
                    case r s of
                        S.Return x => S.Return x
                      | S.Continue (h', s) =>
                        case mf ctx t s of
                            S.Return x => S.Return x
                          | S.Continue (t', s) => S.Continue (h' :: t', s)
                end
    in
        mf
    end

fun foldlMap f s =
    let
        fun fm (ls', s) ls =
            case ls of
                nil => (rev ls', s)
              | h :: t =>
                let
                    val (h', s') = f (h, s)
                in
                    fm (h' :: ls', s') t
                end
    in
        fm ([], s)
    end

fun foldlMapConcat f s =
    let
        fun fm (ls', s) ls =
            case ls of
                nil => (rev ls', s)
              | h :: t =>
                let
                    val (h', s') = f (h, s)
                in
                    fm (List.revAppend (h', ls'), s') t
                end
    in
        fm ([], s)
    end

fun foldlMapPartial f s =
    let
        fun fm (ls', s) ls =
            case ls of
                nil => (rev ls', s)
              | h :: t =>
                let
                    val (h', s') = f (h, s)
                    val ls' = case h' of
                                  NONE => ls'
                                | SOME h' => h' :: ls'
                in
                    fm (ls', s') t
                end
    in
        fm ([], s)
    end

fun search f =
    let
        fun s ls =
            case ls of
                [] => NONE
              | h :: t =>
                case f h of
                    NONE => s t
                  | v => v
    in
        s
    end

fun mapi f =
    let
        fun m i acc ls =
            case ls of
                [] => rev acc
              | h :: t => m (i + 1) (f (i, h) :: acc) t
    in
        m 0 []
    end

end