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(* 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
|
