summaryrefslogtreecommitdiff
path: root/src/mono_reduce.sml
blob: caa3c124bca8aa22e94266528fcf406da18ce9c8 (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
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
(* 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


fun impure (e, _) =
    case e of
        EWrite _ => true
      | EQuery _ => true
      | EAbs _ => false

      | EPrim _ => false
      | ERel _ => false
      | ENamed _ => false
      | ECon (_, _, eo) => (case eo of NONE => false | SOME e => impure e)
      | EFfi _ => false
      | EFfiApp _ => false
      | EApp ((EFfi _, _), _) => false
      | EApp _ => true

      | ERecord xes => List.exists (fn (_, e, _) => impure e) xes
      | EField (e, _) => impure e

      | ECase (e, pes, _) => impure e orelse List.exists (fn (_, e) => impure e) pes

      | EStrcat (e1, e2) => impure e1 orelse impure e2

      | ESeq (e1, e2) => impure e1 orelse impure e2
      | ELet (_, _, e1, e2) => impure e1 orelse impure e2

      | EClosure (_, es) => List.exists impure es


val liftExpInExp = Monoize.liftExpInExp

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 subExpInExp (n, e1) e2 =
    let
        val r = subExpInExp' (n, e1) e2
    in
        (*Print.prefaces "subExpInExp" [("e1", MonoPrint.p_exp MonoEnv.empty e1),
                                      ("e2", MonoPrint.p_exp MonoEnv.empty e2),
                                      ("r", MonoPrint.p_exp MonoEnv.empty r)];*)
        r
    end

fun typ c = c

datatype result = Yes of E.env | No | Maybe

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

      | (PPrim p, EPrim p') =>
        if Prim.equal (p, p') then
            Yes env
        else
            No

      | (PCon (_, PConVar n1, NONE), ECon (_, PConVar n2, NONE)) =>
        if n1 = n2 then
            Yes env
        else
            No

      | (PCon (_, PConVar n1, SOME p), ECon (_, PConVar n2, SOME e)) =>
        if n1 = n2 then
            match (env, p, e)
        else
            No

      | (PCon (_, PConFfi {mod = m1, con = con1, ...}, NONE), ECon (_, PConFfi {mod = m2, con = con2, ...}, NONE)) =>
        if m1 = m2 andalso con1 = con2 then
            Yes env
        else
            No

      | (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
            No

      | (PRecord xps, ERecord xes) =>
        let
            fun consider (xps, env) =
                case xps of
                    [] => Yes env
                  | (x, p, _) :: rest =>
                    case List.find (fn (x', _, _) => x' = x) xes of
                        NONE => No
                      | SOME (_, e, _) =>
                        case match (env, p, e) of
                            No => No
                          | Maybe => Maybe
                          | Yes env => consider (rest, env)
        in
            consider (xps, env)
        end

      | _ => Maybe

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 (x, t, _, e1), loc), e2) =>
        ((*Print.prefaces "Considering" [("e1", MonoPrint.p_exp env e1),
                                       ("e2", MonoPrint.p_exp env e2)];*)
        if impure e2 then
            #1 (reduceExp env (ELet (x, t, e2, e1), loc))
        else
            #1 (reduceExp env (subExpInExp (0, e2) e1)))

      | ECase (disc, pes, _) =>
        let
            fun search pes =
                case pes of
                    [] => e
                  | (p, body) :: pes =>
                    case match (env, p, disc) of
                        No => search pes
                      | Maybe => e
                      | Yes env => #1 (reduceExp env body)
        in
            search pes
        end

      | EField ((ERecord xes, _), x) =>
        (case List.find (fn (x', _, _) => x' = x) xes of
             SOME (_, e, _) => #1 e
           | NONE => e)

      | ELet (x1, t1, (ELet (x2, t2, e1, b1), loc), b2) =>
        let
            val e' = (ELet (x2, t2, e1,
                            (ELet (x1, t1, b1,
                                   liftExpInExp 1 b2), loc)), loc)
        in
            (*Print.prefaces "ELet commute" [("e", MonoPrint.p_exp env (e, loc)),
                                           ("e'", MonoPrint.p_exp env e')];*)
            #1 (reduceExp env e')
        end
      | EApp ((ELet (x, t, e, b), loc), e') =>
        #1 (reduceExp env (ELet (x, t, e,
                                 (EApp (b, liftExpInExp 0 e'), loc)), loc))
      | ELet (x, t, e', b) =>
        if impure e' then
            e
        else
            #1 (reduceExp env (subExpInExp (0, e') b))

      | _ => e

and 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 (Option.map (reduceExp env) eo) s

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