(* HCoop Domtool (http://hcoop.sourceforge.net/)
 * Copyright (c) 2006, Adam Chlipala
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*)

(* Domtool type-checking and reduction environments *)

structure Env :> ENV = struct

open Ast

structure SS = StringSet
structure SM = StringMap

type env = SS.set * (typ * exp option) SM.map
val empty : env = (SS.add (SS.singleton "int", "string"),
		   SM.empty)

fun lookupType (ts, _) name = SS.member (ts, name)
fun lookupVal (_, vs) name =
    case SM.find (vs, name) of
	NONE => NONE
      | SOME (t, _) => SOME t
fun lookupEquation (_, vs) name =
    case SM.find (vs, name) of
	NONE => NONE
      | SOME (_, eqo) => eqo

fun bindType (ts, vs) name = (SS.add (ts, name), vs)
fun bindVal (ts, vs) (name, t, eqo) = (ts, SM.insert (vs, name, (t, eqo)))

end