summaryrefslogtreecommitdiff
path: root/src/mono_reduce.sml
blob: 20d2654744a2875ad33bd54f1c1581c23e6ea252 (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
150
151
152
153
154
(* 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.
 *)

(* Simplify a Mono program algebraically *)

structure MonoReduce :> MONO_REDUCE = struct

open Mono

structure E = MonoEnv
structure U = MonoUtil

val liftExpInExp =
    U.Exp.mapB {typ = fn t => t,
                exp = fn bound => fn e =>
                                     case e of
                                         ERel xn =>
                                         if xn < bound then
                                             e
                                         else
                                             ERel (xn + 1)
                                       | _ => e,
                bind = fn (bound, U.Exp.RelE _) => bound + 1
                        | (bound, _) => bound}

val subExpInExp =
    U.Exp.mapB {typ = fn t => t,
                exp = fn (xn, rep) => fn e =>
                                  case e of
                                      ERel xn' =>
                                      (case Int.compare (xn', xn) of
                                           EQUAL => #1 rep
                                         | GREATER=> ERel (xn' - 1)
                                         | LESS => e)
                                    | _ => e,
                bind = fn ((xn, rep), U.Exp.RelE _) => (xn+1, liftExpInExp 0 rep)
                        | (ctx, _) => ctx}

fun bind (env, b) =
    case b of
        U.Decl.Datatype (x, n, xncs) => E.pushDatatype env x n xncs
      | U.Decl.RelE (x, t) => E.pushERel env x t NONE
      | U.Decl.NamedE (x, n, t, eo, s) => E.pushENamed env x n t eo s

fun typ c = c

fun match (env, p : pat, e : exp) =
    case (#1 p, #1 e) of
        (PWild, _) => SOME env
      | (PVar (x, t), _) => SOME (E.pushERel env x t (SOME e))

      | (PPrim p, EPrim p') =>
        if Prim.equal (p, p') then
            SOME env
        else
            NONE

      | (PCon (PConVar n1, NONE), ECon (PConVar n2, NONE)) =>
        if n1 = n2 then
            SOME env
        else
            NONE

      | (PCon (PConVar n1, SOME p), ECon (PConVar n2, SOME e)) =>
        if n1 = n2 then
            match (env, p, e)
        else
            NONE

      | (PCon (PConFfi {mod = m1, con = con1, ...}, NONE), ECon (PConFfi {mod = m2, con = con2, ...}, NONE)) =>
        if m1 = m2 andalso con1 = con2 then
            SOME env
        else
            NONE

      | (PCon (PConFfi {mod = m1, con = con1, ...}, SOME ep), ECon (PConFfi {mod = m2, con = con2, ...}, SOME e)) =>
        if m1 = m2 andalso con1 = con2 then
            match (env, p, e)
        else
            NONE

      | (PRecord xps, ERecord xes) =>
        let
            fun consider (xps, env) =
                case xps of
                    [] => SOME env
                  | (x, p, _) :: rest =>
                    case List.find (fn (x', _, _) => x' = x) xes of
                        NONE => NONE
                      | SOME (_, e, _) =>
                        case match (env, p, e) of
                            NONE => NONE
                          | SOME env => consider (rest, env)
        in
            consider (xps, env)
        end

      | _ => NONE

fun exp env e =
    case e of
        ERel n =>
        (case E.lookupERel env n of
             (_, _, SOME e') => #1 e'
           | _ => e)
      | ENamed n =>
        (case E.lookupENamed env n of
             (_, _, SOME e', _) => #1 e'
           | _ => e)

      | EApp ((EAbs (_, _, _, e1), loc), e2) =>
        #1 (reduceExp env (subExpInExp (0, e2) e1))

      | ECase (disc, pes, _) =>
        (case ListUtil.search (fn (p, body) =>
                                  case match (env, p, disc) of
                                      NONE => NONE
                                    | SOME env => SOME (#1 (reduceExp env body))) pes of
             NONE => e
           | SOME e' => e')

      | _ => e

and reduceExp env = U.Exp.mapB {typ = typ, exp = exp, bind = bind} env

fun decl env d = d

val reduce = U.File.mapB {typ = typ, exp = exp, decl = decl, bind = bind} E.empty

end