(* Copyright 1996 by AT&T Bell Laboratories *)
(* sigmatch.sml *)

signature SIGMATCH =
sig

  (*** these four functions are only called inside elabmod.sml ***)
  val matchStr : 
       {sign     : Modules.Signature, 
        str      : Modules.Structure,
        strExp   : Modules.strExp,
        evOp     : EntPath.entVar option,
        depth    : DebIndex.depth,
        entEnv   : Modules.entityEnv,
        rpath    : InvPath.path,
        statenv  : StaticEnv.staticEnv,
        region   : SourceMap.region,
        compInfo : ElabUtil.compInfo} -> {resDec : Absyn.dec,
                                          resStr : Modules.Structure,
                                          resExp : Modules.strExp}

  val matchFct : 
       {sign     : Modules.fctSig,
        fct      : Modules.Functor,
        fctExp   : Modules.fctExp,
        depth    : DebIndex.depth,
        entEnv   : Modules.entityEnv,
        rpath    : InvPath.path,
        statenv  : StaticEnv.staticEnv,
        region   : SourceMap.region,
        compInfo : ElabUtil.compInfo} -> {resDec : Absyn.dec,
                                          resFct : Modules.Functor,
                                          resExp : Modules.fctExp}

  val packStr : 
       {sign     : Modules.Signature, 
        str      : Modules.Structure,
        strExp   : Modules.strExp,
        depth    : DebIndex.depth,
        entEnv   : Modules.entityEnv,
        rpath    : InvPath.path,
        statenv  : StaticEnv.staticEnv,
        region   : SourceMap.region,
        compInfo : ElabUtil.compInfo} -> {resDec : Absyn.dec,
                                          resStr : Modules.Structure,
                                          resExp : Modules.strExp}

  val applyFct : 
       {fct      : Modules.Functor,
        fctExp   : Modules.fctExp,
        argStr   : Modules.Structure, 
        argExp   : Modules.strExp,
        evOp     : EntPath.entVar option,
        depth    : DebIndex.depth,
        epc      : EntPathContext.context,                                
        statenv  : StaticEnv.staticEnv,
	rpath    : InvPath.path,
        region   : SourceMap.region,
        compInfo : ElabUtil.compInfo} -> {resDec : Absyn.dec,
                                          resStr : Modules.Structure,
                                          resExp : Modules.strExp}


  val debugging : bool ref
  val showsigs : bool ref

end (* signature SIGMATCH *)


structure SigMatch: SIGMATCH =
struct

local structure A  = Absyn
      structure B  = Bindings
      structure DA = Access
      structure DI = DebIndex
      structure EE = EntityEnv
      structure EM = ErrorMsg
      structure EP = EntPath
      structure EPC = EntPathContext
      structure EU = ElabUtil
      structure EV = EvalEntity
      structure INS = Instantiate
      structure II = InlInfo
      structure IP = InvPath
      structure M  = Modules
      structure MU = ModuleUtil
      structure PP = PrettyPrint
      structure S  = Symbol
      structure SE = StaticEnv
      structure SP = SymPath
      structure ST = Stamps
      structure T  = Types
      structure TU = TypesUtil
      structure V  = VarCon

      open Types Modules VarCon ElabDebug

in
exception BadBinding

val debugging = Control.CG.smdebugging (* ref false *)
val showsigs = ref false

val say = Control.Print.say
fun debugmsg (msg: string) =
      if !debugging then (say msg; say "\n") else ()

fun bug msg = EM.impossible ("SigMatch:" ^ msg)
val nth = List.nth
fun for l f = app f l

fun symbolsToString []  = ""
  | symbolsToString [n] = S.name n
  | symbolsToString (n::r) =
      concat(S.name n :: foldr (fn(n,b) => (","::S.name n::b)) [] r)

val BogusTy = UNDEFty 

(* 
 * Bogus coercion expressions returned by the matching functions.  These
 * should never be evaluated. 
 *)

val bogusStrExp = M.VARstr []
val bogusFctExp = M.VARfct []

fun showStr (msg,str) =
    withInternals(fn () =>
      debugPrint debugging
       (msg,
	(fn pps => fn str =>
	    PPModules.ppStructure pps (str, SE.empty, 100)),
	str))

fun exnRep (DA.EXN _, dacc) = DA.EXN dacc
  | exnRep _ = bug "unexpected conrep in exnRep"

fun isNamed(SOME _) = true
  | isNamed _ = false

val anonSym = S.strSymbol "<anonymousStr>"
val anonFsym = S.fctSymbol "<anonymousFct>"
val paramSym = S.strSymbol "<FsigParamInst>"

fun ident _ = ()

(* returns true and the new instantiations if actual type > spec type *)
(* matches an abstract version of a type with its actual version *)
fun absEqvTy (spec, actual, dinfo) : (ty list * tyvar list * ty * bool) =
  let val actual = TU.prune actual
      val spec = TU.prune spec
      val (actinst, insttys0) = TU.instantiatePoly actual
      val (specinst, stys) = TU.instantiatePoly spec
      val _ = ListPair.app Unify.unifyTy (insttys0, stys)

      (*
       * This is a gross hack. Inlining-information such as primops 
       * (or inline-able expressions) are propagated through signature
       * matching. However, their types may change. The following code
       * is to figure out the proper type application arguments, insttys.
       * The typechecker does similar hack. We will clean this up in the
       * future (ZHONG).
       *)
      val insttys = 
       (case dinfo 
         of II.INL_PRIM(_, SOME st) =>
              (let val (actinst', insttys') = TU.instantiatePoly st
                in Unify.unifyTy(actinst', actinst) handle _ => ();
                   insttys'
               end)
          | _ =>insttys0)

      val res = (Unify.unifyTy(actinst, specinst); true) handle _ => false

      val instbtvs = map TU.tyvarType insttys0
      (* should I use stys here instead, why insttys0 ? *)

   in (insttys, instbtvs, specinst, res)
  end

fun eqvTnspTy (spec, actual, dinfo) : (ty list * tyvar list) = 
  let val actual = TU.prune actual
      val (actinst, insttys) = TU.instantiatePoly actual

      (*
       * This is a gross hack. Inlining-information such as primops 
       * (or inline-able expressions) are propagated through signature
       * matching. However, their types may change. The following code
       * is to figure out the proper type application arguments, insttys.
       * The typechecker does similar hack. We will clean this up in the
       * future (ZHONG).
       *)
      val insttys = 
       (case dinfo 
         of II.INL_PRIM(_, SOME st) =>
              (let val (actinst', insttys') = TU.instantiatePoly st
                in Unify.unifyTy(actinst', actinst) handle _ => ();
                   insttys'
               end)
          | _ =>insttys)

      val (specinst, stys) = TU.instantiatePoly spec
      val _ = ((Unify.unifyTy(actinst, specinst))
               handle _ => bug "unexpected types in eqvTnspTy")
      val btvs = map TU.tyvarType stys
             
   in (insttys, btvs)
  end


(**************************************************************************
 *                                                                        *
 * Matching a structure against a signature:                              *
 *                                                                        *
 *  val matchStr1 : Signature * Structure * S.symbol * DI.depth *         *
 *                  entityEnv * EP.entPath * IP.path * staticEnv *        *
 *                  region * EU.compInfo                                  *
 *                   -> A.dec * M.Structure * M.strExp                    *
 *                                                                        *
 * WARNING: epath is an inverse entPath, so it has to be reversed to      *
 *          produce an entPath.                                           *
 *                                                                        *
 **************************************************************************)
fun matchStr1(specSig as SIG{closed, fctflag, stamp=sigStamp, elements=sigElements, ...},
              str as STR{sign = SIG{elements=strElements, 
                                    stamp=strSigStamp, ...},
                         rlzn = {stamp=strStamp, entities=strEntEnv, ...}, 
                         access = rootAcc, info=rootInfo},
              strName : S.symbol, depth, matchEntEnv, 
              epath: EP.entVar list, rpath: IP.path, statenv, region,
	      compInfo as {mkStamp, mkLvar=mkv, error, ...}: EU.compInfo) =

let 

val err = error region
val _ = let fun h pps sign =PPModules.ppSignature pps (sign,statenv,6)
            val s = ">>matchStr1 - specSig :"
         in debugPrint (showsigs) (s, h, specSig)
        end

fun matchTypes (spec, actual, dinfo, name) : (T.ty list * T.tyvar list) = 
  if TU.compareTypes(spec, actual) then 
       let val (insttys, btvs) = eqvTnspTy(spec, actual, dinfo)
        in (insttys, btvs)
       end
  else (err EM.COMPLAIN 
            "value type in structure doesn't match signature spec"
            (fn ppstrm =>
                 (PPType.resetPPType();
                  PP.add_newline ppstrm;
                  app (PP.add_string ppstrm) ["  name: ", S.name name];
                  PP.add_newline ppstrm;
                  PP.add_string ppstrm "spec:   ";
                  PPType.ppType statenv ppstrm spec;
                  PP.add_newline ppstrm;
                  PP.add_string ppstrm "actual: ";
                  PPType.ppType statenv ppstrm actual));
        ([],[]))

fun complain s = err EM.COMPLAIN s EM.nullErrorBody
fun complain' x = (complain x; raise BadBinding)

(* 
 * Compare datacon names of spec and actual datatype; this uses 
 * the fact that datacons have been sorted by name. 
 *)
fun compareDcons(spec,actual) =
  let fun comp(l1 as dc1::r1, l2 as dc2::r2, s_only, a_only) =
            if S.eq(dc1,dc2) then comp(r1,r2,s_only,a_only)
            else if S.symbolGt(dc1,dc2) 
                 then comp(l1,r2,s_only,dc2::a_only)
                 else comp(r1,l2,dc1::s_only,a_only)

        | comp([], [], s_only, a_only) = (rev s_only, rev a_only)
        | comp([], r, s_only, a_only)  = (rev s_only, rev a_only @ r)
        | comp(r, [], s_only, a_only)  = (rev s_only @ r, rev a_only)
   in comp(spec,actual,[],[])
  end

fun checkTycBinding(_,T.ERRORtyc,_) = ()
  | checkTycBinding(specTycon,strTycon,entEnv) =
  let val specName = S.name(TU.tycName specTycon)
   in case specTycon
       of GENtyc{stamp=s,arity,kind=specKind,eq=ref eqprop,...} =>
            if arity <> TU.tyconArity strTycon
            then complain' ("tycon arity for " ^ specName
                            ^ " does not match specified arity")
            else (case (specKind, TU.unWrapDefStar strTycon)
                   of (DATATYPE{index,family={members,...} ,...},
                       GENtyc{arity=a',kind=DATATYPE{index=index',
                              family={members=members',...}, ...},
                              ...}) =>
                         let val specDconSig = #dcons(Vector.sub(members,index))
                             val strDconSig = #dcons(Vector.sub(members',index'))
                             val specnames = map #name specDconSig
                             val strnames = map #name strDconSig

                             val _ = app (fn s => 
                                            (debugmsg (S.name s))) specnames
                             val _ = debugmsg "******"
                             val _ = app (fn s => 
                                            (debugmsg (S.name s))) strnames

                          in case compareDcons (specnames, strnames)
                              of ([],[]) => ()
                               | (s_only, a_only) =>
                                   complain'(concat(List.concat
                                    [["datatype ",specName,
                                      " does not match specification"],
                                     case s_only
                                      of [] => []
                                       | _  => 
                                          ["\n   constructors in spec only: ",
                                           symbolsToString s_only],
                                     case a_only
                                      of [] => []
                                       | _  => 
                                          ["\n   constructors in actual only: ",
                                           symbolsToString a_only]]))
                         end
                    | (DATATYPE _, _) => 
                         complain'("type "^specName^" must be a datatype")
                    | (FORMAL, _) =>
                         if eqprop=YES andalso not(EqTypes.isEqTycon strTycon)
                         then complain'("type " ^ specName ^
                                        " must be an equality type")
                         else ()
                    | _ =>
                         (debugPrint(debugging)("specTycon: ",
                          PPType.ppTycon statenv, specTycon);
                          debugPrint(debugging)("strTycon: ",
                          PPType.ppTycon statenv, strTycon);
                          bug "checkTycBinding 1" ))

        | DEFtyc{tyfun=TYFUN{arity,body},strict,stamp,path} => 
            let val ntyfun = TYFUN{arity=arity,body=MU.transType entEnv body}
                val specTycon' = DEFtyc{tyfun=ntyfun,strict=strict,
                                        stamp=stamp,path=path}
             in if TU.equalTycon(specTycon',strTycon)
                then ()
                else (debugPrint(debugging)("specTycon': ",
			PPType.ppTycon statenv, specTycon);
                      debugPrint(debugging)("strTycon: ",
                        PPType.ppTycon statenv, strTycon);
		      complain'("type " ^ specName ^
				" does not match definitional specification"))
            end
        | ERRORtyc => raise BadBinding
        | _ => bug "checkTycBinding 2"
  end

(*** lookStr is only used inside the checkSharing function ***)
fun lookStr (elements,entEnv) (SP.SPATH spath) : (M.Signature * M.entity) =
  let fun loop ([sym],elements,entEnv) =
            ((case MU.getSpec(elements,sym)
               of STRspec{entVar,sign,...} =>
                   (debugmsg ("$lookStr.1: "^S.name sym^", "^EP.entVarToString entVar);
		   (sign,EE.look(entEnv,entVar)))
                | _ => bug "looStr 1b")
              handle MU.Unbound _ => bug "lookStr 1c")

        | loop (sym::rest,elements,entEnv) =
            ((case MU.getSpec(elements,sym)
               of STRspec{sign=SIG{elements,...},entVar,...} =>
                    (case EE.look(entEnv,entVar)
                      of STRent{entities,...} => 
                   (debugmsg ("$lookStr.2: "^S.name sym^", "^EP.entVarToString entVar);			  loop(rest,elements,entities))
		       | ERRORent => (ERRORsig,ERRORent)
                       | _ => bug "lookStr 2a")
                | _ => bug "lookStr 2b")
              handle MU.Unbound _ => bug "lookStr 2c")

        | loop _ = bug "lookStr 3"
   in loop(spath,elements,entEnv)
  end

(*** lookTyc is only used inside the checkSharing function ***)
fun lookTyc (elements,entEnv) (SP.SPATH spath) : T.tycon =
  let fun loop ([sym],elements,entEnv) =
            ((case MU.getSpec(elements,sym)
               of TYCspec{entVar,...} =>
                    (case EE.look(entEnv,entVar)
                      of TYCent tycon => tycon
		       | ERRORent => ERRORtyc
                       | _ => bug "lookTyc 1a")
                | _ => bug "looTyc 1b")
              handle MU.Unbound _ => bug "lookTyc 1c")

        | loop (sym::rest,elements,entEnv) =
            ((case MU.getSpec(elements,sym)
               of STRspec{sign=SIG{elements,...},entVar,...} =>
                 (case EE.look(entEnv,entVar)
                   of STRent{entities,...} => loop(rest,elements,entities)
		    | ERRORent => ERRORtyc
                    | _ => bug "lookTyc 2a")
                | _ => bug "lookTyc 2b")
             handle MU.Unbound _ => bug ("lookTyc 2c:"^Symbol.name sym^
					 SP.toString(SP.SPATH spath)))

        | loop _ = bug "lookTyc 3"
   in loop(spath,elements,entEnv)
  end

(*** verify whether all the sharing constraints are satisfied ***)
fun checkSharing(sign as ERRORsig, entEnv) = ()
      (* don't do anything if an error has occured, resulting in an ERRORsig *)
  | checkSharing(sign as SIG{elements, typsharing, strsharing,...},
		 entEnv) =
      let fun errmsg sp x = SP.toString x ^ " # " ^ SP.toString sp

	  fun eqTyc(_,ERRORtyc) = true
	    | eqTyc(ERRORtyc,_) = true
	    | eqTyc(tyc1,tyc2) = TU.equalTycon(tyc1,tyc2)

          val lookStr = lookStr (elements,entEnv)


	  fun commonElements(SIG{elements=elems1,...},SIG{elements=elems2,...}) =
	      let fun elemGt ((s1,_),(s2,_)) = S.symbolGt(s1,s2)
		  val elems1 = Sort.sort elemGt elems1
	          val elems2 = Sort.sort elemGt elems2
		  fun intersect(e1 as ((s1,spec1)::rest1),
				e2 as ((s2,spec2)::rest2)) =
	              if S.eq(s1,s2) then (s1,spec1,spec2)::intersect(rest1,rest2)
		      else if S.symbolGt(s1,s2) then intersect(e1,rest2)
		      else intersect(rest1,e2)
		    | intersect(_,_) = nil
	       in intersect(elems1,elems2)
	      end
	    | commonElements _ = bug "commonElements"


	  fun appPairs test nil = ()
	    | appPairs test (a::r) =
	        (app (fn x => test(a,x)) r; appPairs test r)

	  fun compStr((p1,(sign1,ent1)),
		      (p2,(sign2,ent2))) = 
	       (case (ent1,ent2)
		  of (STRent{stamp=s1,entities=ee1,...},
		      STRent{stamp=s2,entities=ee2,...}) =>
		      if ST.eq(s1,s2) then () (* shortcut! *)
		      else if MU.eqSign(sign1,sign2) then
			     let val _ = debugmsg "$compStr: equal signs"
				 val SIG{elements,...} = sign1
			      in for elements (fn 
				    (sym,TYCspec{entVar,...}) => 
				      let val TYCent tyc1 = EE.look(ee1,entVar)
				          val TYCent tyc2 = EE.look(ee2,entVar)
				       in if eqTyc(tyc1,tyc2) then ()
					  else complain(
					        concat["implied type sharing violation: ",
						       errmsg (SP.extend(p1,sym))
						         (SP.extend(p2,sym))])
				      end
				  | (sym,STRspec{entVar,sign,...}) => 
				      let val ent1' = EE.look(ee1,entVar)
				          val ent2' = EE.look(ee2,entVar)
				       in compStr((SP.extend(p1,sym),(sign,ent1')),
						  (SP.extend(p2,sym),(sign,ent2')))
				      end
				  | _ => ())
			     end
			   else
			     let val _ = debugmsg "$compStr: unequal signs"
				 val common = commonElements(sign1,sign2)
			      in for common (fn 
				   (sym,TYCspec{entVar=v1,...},
				        TYCspec{entVar=v2,...}) =>
				      let val TYCent tyc1 = EE.look(ee1,v1)
				          val TYCent tyc2 = EE.look(ee2,v2)
				       in if eqTyc(tyc1,tyc2) then ()
					  else complain(
					        concat["type sharing violation: ",
						       errmsg (SP.extend(p1,sym))
						         (SP.extend(p2,sym))])
				      end
				 | (sym,STRspec{entVar=v1,sign=sign1',...},
				        STRspec{entVar=v2,sign=sign2',...}) =>
				      let val str1 = EE.look(ee1,v1)
				          val str2 = EE.look(ee2,v2)
				       in compStr((SP.extend(p1,sym),(sign1',str1)),
						  (SP.extend(p2,sym),(sign2',str2)))
				      end
				 | _ => ()) (* values, constructors, functors *)
			     end
		   | (ERRORent,_) => ()  (* error upstream *)
		   | (_,ERRORent) => ()) (* error upstream *)
	   
          fun checkStr (paths) =
	      let val pathstrs = map (fn p => (p,lookStr p)) paths
	       in appPairs compStr pathstrs
	      end

	  fun checkTyc0 (firstPath, rest) =
            let val lookTyc = lookTyc (elements,entEnv)
		val errMsg = errmsg firstPath
		val first = lookTyc firstPath
		fun checkPath p = 
		    if eqTyc(first, lookTyc p) then ()
		    else complain(concat["type sharing violation: ",errMsg p])
             in app checkPath rest
            end

          fun checkTyc (sp::rest) = checkTyc0(sp,rest)

       in app checkStr strsharing;
          app checkTyc typsharing
      end

(* 
 * Matching: Go through the `elements' of the specified signature, and 
 * construct a corresponding realization from entities found in the given 
 * structure.  The structure's entities are found by using the entPath in 
 * each of the given structure signature's elements to access the given 
 * structure's realization = stored entEnv.  Recurse into substructures.  
 * Build the formal realization in parallel.  Finally check sharing 
 * constraints.
 *)

(* 
 * val matchElems : 
 *      (S.symbol * spec) list * entEnv * entityDec list * A.dec list 
 *       * B.binding list 
 *       -> (entEnv * entityDec list * A.dec list * B.binding list)
 *
 * Given the elements and the entities of a structure S, and a spec
 * from a signature, extend the realization (entityEnv) with the
 * entity specified by the spec, extend the list of
 * coercions (entity declarations) with a declaration which
 * will evaluate to the newly created entity, and extend the thinning.
 *
 * Assumption: if a match error occurs, then the resulting thinning
 * and the list of entityDecs will never be used -- they will not be
 * well-formed in case of errors. 
 *)

fun matchDefStr0(sigElements,signD,rlznD,signM,rlznM) =
    let val dropVals = List.filter
	                (fn (s,(TYCspec _ | STRspec _ )) => true | _ => false)
	fun elemGt ((s1,_),(s2,_)) = S.symbolGt(s1,s2)
	val commonDM =
	    if MU.eqSign(signD,signM) then
	      let val SIG{elements=elems,...} = signD
	          val elems = Sort.sort elemGt (dropVals elems)
	       in map (fn (s,spec) => (s,spec,spec)) elems
	      end
	    else
	      let val SIG{elements=elemsD,...} = signD
		  val SIG{elements=elemsM,...} = signM
		  val elemsD = Sort.sort elemGt (dropVals elemsD)
		  val elemsM = Sort.sort elemGt (dropVals elemsM)
		  fun intersect(e1 as ((s1,spec1)::rest1),
				e2 as ((s2,spec2)::rest2)) =
		      if S.eq(s1,s2) then (s1,spec1,spec2)::intersect(rest1,rest2)
		      else if S.symbolGt(s1,s2) then intersect(e1,rest2)
		      else intersect(rest1,e2)
		    | intersect(_,_) = nil
	       in intersect(elemsD,elemsM)
	      end
	val sigElements' = dropVals sigElements
	fun intersect'(elems1 as ((sym1,x)::rest1),
		       elems2 as ((sym2,y,z)::rest2)) =
	    if S.eq(sym1,sym2) then
	      (sym1,x,y,z)::intersect'(rest1,rest2)
	    else if S.symbolGt(sym1,sym2) then
	      intersect'(elems1,rest2) (* discard sym2 *)
	    else intersect'(rest1,elems2) (* discard sym1 *)
	  | intersect'(_,_) = nil
	val common = intersect'(sigElements',commonDM)
	fun loop nil = true
	  | loop ((sym,spec,specD,specM)::rest) =
	    (case spec
	       of TYCspec _ =>
		   let val TYCspec{entVar=evD,...} = specD
		       val TYCspec{entVar=evM,...} = specM
		       val {entities=eeD,...} = rlznD
		       val {entities=eeM,...} = rlznM
		       val TYCent tycD = EE.look(eeD,evD)
		       val TYCent tycM = EE.look(eeM,evM)
		    in TU.equalTycon(tycD,tycM)
		   end
		| STRspec{sign=SIG{elements,...},...} =>
		   let val STRspec{entVar=evD,sign=signD',...} = specD
		       val STRspec{entVar=evM,sign=signM',...} = specM
		       val {entities=eeD,...} = rlznD
		       val {entities=eeM,...} = rlznM
		       val STRent rlznD' = EE.look(eeD,evD)
		       val STRent rlznM' = EE.look(eeM,evM)
		    in matchDefStr0(elements,signD',rlznD',signM',rlznM')
		   end
		| _ => bug "matchStr")
     in loop common
    end

fun matchDefStr(sigElements,specStr,matchStr) =
    case (specStr,matchStr)
      of (STR{sign=signD,rlzn=rlznD,...},STR{sign=signM,rlzn=rlznM,...}) =>
	  let val {stamp=sD,...} = rlznD
	      val {stamp=sM,...} = rlznM
	   in if ST.eq(sD,sM) (* eqOrigin *)
	      then true
	      else matchDefStr0(sigElements,signD,rlznD,signM,rlznM)
	  end
       | _ => bug "matchDefStr"

fun matchElems ([], entEnv, entDecs, decs, bindings, succeed) =
      (entEnv, rev entDecs, rev decs, rev bindings, succeed)

  | matchElems ((sym, spec) :: elems, entEnv, entDecs, decs, bindings, succeed) =
    
     let val _ = debugmsg ">>matchElems"
         fun matchErr (kindOp: string option) =
           let val entEnv' = 
                 case MU.getSpecVar spec
                  of SOME v => EE.bind(v, ERRORent, entEnv)
                   | NONE => entEnv

               (* synthesize a new error binding to remove improper error
                  messages on inlInfo (ZHONG) *) 
               val bindings' = 
                 case spec
                  of TYCspec _ => bindings
                   | CONspec {slot=NONE, ...} => bindings
                   | _ => (B.CONbind bogusEXN)::bindings

            in case kindOp
		 of SOME kind =>
		      complain("unmatched " ^ kind ^ " specification: " ^ S.name sym)
		  | NONE => ();
               matchElems(elems, entEnv', entDecs, decs, bindings', false)
           end

         fun typeInMatched (kind,typ) = 
               (MU.transType entEnv typ) 
                  handle EE.Unbound => 
                    (debugPrint (debugging) (kind, PPType.ppType statenv,typ);
                     raise EE.Unbound)

         fun typeInOriginal (kind,typ) = 
               (MU.transType strEntEnv typ) 
                  handle EE.Unbound => 
                    (debugPrint (debugging) (kind, PPType.ppType statenv,typ);
                     raise EE.Unbound)

      in case spec
          of TYCspec{spec=specTycon,entVar,scope} =>
              (let val _ = debugmsg(String.concat[">>matchElems TYCspec: ",
                                                  S.name sym, ", ",
                                                  ST.stampToString entVar])
                   val (strTycon, strEntVar) =
                          MU.getTyc(strElements, strEntEnv, sym)
                          handle EE.Unbound =>
                            (debugPrint(debugging) ("strEntEnv: ", 
                              (fn pps => fn ee => 
                                 PPModules.ppEntityEnv pps (ee,statenv,6)),
                              strEntEnv); raise EE.Unbound)

                   val _ = debugmsg ("--matchElems TYCspec - strEntVar: "^
                                     ST.stampToString strEntVar)

                   (*** DAVE: please check the following ! ***)
                   val tycEntExp = 
                     case epath of [] => CONSTtyc strTycon
		                 | _ => VARtyc(rev(strEntVar::epath))

                   val _ = debugmsg "--matchElems TYCspec >> checkTycBinding"
                   val _ = checkTycBinding(specTycon, strTycon, entEnv)
                   val entEnv' = EE.bind(entVar, TYCent strTycon, entEnv) 
                   val entDecs' = TYCdec(entVar, tycEntExp) :: entDecs
                   val _ = debugmsg "<<matchElems TYCspec << checkTycBinding"

                in matchElems(elems, entEnv', entDecs', decs, bindings, succeed)
               end handle MU.Unbound sym => matchErr (SOME "type")
                        | BadBinding => matchErr NONE
                        | EE.Unbound =>
                            (debugmsg ("$matchElems(TYCspec): "^S.name sym);
                             raise EE.Unbound))

           | STRspec{sign=thisSpecSig, entVar, def, ...} =>
              (let val _ = debugmsg(String.concat["--matchElems STRspec: ",
                                                  S.name sym,", ",
                                                  ST.stampToString entVar])
                   val (strStr, strEntVar) = 
                     MU.getStr(strElements, strEntEnv, sym, rootAcc, rootInfo)

		   (* verify spec definition, if any *)
		     (* BUG: shallow test, comparing stamps -- 
		      * needs to be augmented with component-wise test when
		      * stamps disagree [dbm] *)
		     (* how should this verification interact with signatures? *)
		   val _ = 
		       case def
			 of NONE => ()
			  | SOME(sd,_) =>
 			     let val specStr = MU.strDefToStr(sd,entEnv) 
 			      in if matchDefStr(sigElements,specStr,strStr) then ()
 			         else 
                                  (case sd
 				    of M.VARstrDef(sign,ep) =>
 					debugmsg("spec def VAR: "^
 					 EP.entPathToString ep ^ "\n")
 			             | M.CONSTstrDef _ =>
 					debugmsg("spec def CONST\n");
 				   showStr("specStr: ", specStr);
 				   showStr("strStr:  ", strStr);
 				   complain("structure def spec for "^
					    S.name sym ^ " not matched"))
 			     end

                   val epath' = strEntVar::epath
                   val rpath' = IP.extend(rpath, sym)
                   val (thinDec, thinStr, strExp) = 
                     matchStr1(thisSpecSig, strStr, sym, depth, entEnv, epath',
                               rpath', statenv, region, compInfo)

                   val entEnv' = 
                     let val strEnt = 
                           case thinStr of M.STR{rlzn, ...} => rlzn
                                         | _ => M.bogusStrEntity
                      in EE.bind(entVar, M.STRent strEnt, entEnv)
                     end

                   val entDecs' = M.STRdec(entVar, strExp, sym) :: entDecs 
                   val decs' = thinDec :: decs
                   val bindings' = (B.STRbind thinStr)::bindings

                in matchElems(elems, entEnv', entDecs', decs', bindings', succeed)
               end handle MU.Unbound sym => matchErr (SOME "structure"))

           | FCTspec{sign=specSig, entVar, ...} => 
              (let val _ = debugmsg(String.concat["--matchElems FCTspec: ",
                                                  S.name sym,", ",
                                                  ST.stampToString entVar])

                   val (strFct, fctEntVar) = 
                     MU.getFct(strElements, strEntEnv, sym, rootAcc, rootInfo)
                   val exp' = M.VARfct(rev(fctEntVar::epath))
                   val rpath' = IP.extend(rpath,sym)
                   val (thinDec, thinFct, fctExp) = 
                     matchFct1(specSig, strFct, sym, depth, entEnv, exp', 
                               rpath', statenv, region, compInfo)

                   val entEnv' = 
                     let val fctEnt = 
                           case thinFct of M.FCT{rlzn, ...} => rlzn
                                         | _ => M.bogusFctEntity
                      in EE.bind(entVar, M.FCTent fctEnt, entEnv)
                     end

                   val entDecs' = M.FCTdec(entVar, fctExp) :: entDecs 
                   val decs' = thinDec :: decs
                   val bindings' = (B.FCTbind thinFct)::bindings

                in matchElems(elems, entEnv', entDecs', decs', bindings', succeed)
               end handle MU.Unbound sym => matchErr(SOME "functor"))

           | VALspec{spec=spectyp, ...} => 
              ((case (MU.getSpec(strElements, sym))
                 of VALspec{spec=acttyp, slot=actslot} =>
                   let val spectyp = typeInMatched("$specty(val/val)", spectyp)
                       val acttyp = typeInOriginal("$actty(val/val)", acttyp)
                       val dacc = DA.selAcc(rootAcc, actslot)
                       val dinfo = II.selInfo(rootInfo, actslot)
                       val (instys,btvs) = 
                         matchTypes(spectyp, acttyp, dinfo, sym)

                       val spath = SP.SPATH[sym]
                       val actvar = VALvar{path=spath, typ=ref acttyp,
                                           access=dacc, info=dinfo}

                       val (decs', nv) = 
                         case (TU.headReduceType acttyp, 
                               TU.headReduceType spectyp)
                          of ((POLYty _, _) | (_, POLYty _))=> 
                              let val acc = DA.namedAcc(sym, mkv)
                                  val specvar = 
                                    VALvar{path=spath, typ=ref spectyp,
                                           access=acc, info=dinfo}
                                  val vb = 
                                    A.VB {pat=A.VARpat specvar,
                                          exp=A.VARexp(ref actvar, instys),
                                          boundtvs=btvs, tyvars=ref []}

                               in ((A.VALdec [vb])::decs, specvar)
                              end
                           | _ => (decs, actvar)

                       val bindings' = (B.VALbind nv)::bindings

                    in matchElems(elems, entEnv, entDecs, decs', bindings', succeed)
                   end

                  | CONspec{spec=DATACON{typ=acttyp, name, const,
                                         rep, sign, lazyp}, slot} => 
                   let val spectyp = typeInMatched("$specty(val/con)", spectyp)
                       val acttyp = typeInOriginal("$actty(val/con)", acttyp)
                       val (instys, btvs) = 
                         matchTypes(spectyp, acttyp, II.nullInfo, name)

                       val nrep = 
                         case slot 
                          of SOME s => exnRep(rep, DA.selAcc(rootAcc, s))
                           | NONE => rep
         
                       val (decs', bindings') =
                         let val con = 
                               DATACON{typ=acttyp, name=name, const=const, 
                                       rep=nrep, sign=sign, lazyp=lazyp}
                             val acc = DA.namedAcc(name, mkv)
                             val specvar = 
                               VALvar{path=SP.SPATH[name], access=acc,
                                      info=II.nullInfo, typ=ref spectyp}
                             val vb = 
                               A.VB {pat=A.VARpat specvar,
                                     exp=A.CONexp(con, instys),
                                     boundtvs=btvs, tyvars=ref []}
                          in ((A.VALdec [vb])::decs, 
                              (B.VALbind specvar)::bindings)
                         end
                    in matchElems(elems, entEnv, entDecs, decs', 
                                  bindings', succeed)
                   end

               | _ => bug "matchVElem.1")
             handle MU.Unbound sym => matchErr(SOME "value"))

           | CONspec{spec=DATACON{name, typ=spectyp, lazyp,
                                  rep=specrep, ...},...} => 
             ((case MU.getSpec(strElements, sym)
                of CONspec{spec=DATACON{typ=acttyp, rep=actrep, const, 
                                      sign, ...}, slot} =>
                   if (DA.isExn specrep) = (DA.isExn actrep) then
                   let val spectyp = typeInMatched("$specty(con/con)", spectyp)
                       val acttyp = typeInOriginal("$actty(con/con)", acttyp)
                       val _ = matchTypes(spectyp, acttyp, II.nullInfo, name)

                       val bindings' =
                         case slot 
                          of NONE => bindings 
                           | SOME s => 
                               let val dacc = DA.selAcc(rootAcc, s)
                                   val nrep = exnRep(actrep, dacc) 
                                   val con = DATACON{typ=acttyp, name=name,
                                                     const=const, rep=nrep,
                                                     sign=sign, lazyp=lazyp}
                                in (B.CONbind(con)) :: bindings
                               end

                    in matchElems(elems, entEnv, entDecs, decs, bindings', succeed)
                   end
                   else raise MU.Unbound sym

                 | VALspec _ =>
		   if DA.isExn specrep then matchErr(SOME "exception")
                   else matchErr(SOME "constructor")
		 | _ => bug "matchVElem.2")
              handle MU.Unbound sym => 
                     if DA.isExn specrep then matchErr(SOME "exception")
                     else matchErr(SOME "constructor"))

     end (* function matchElems *)

fun matchIt entEnv = 
  let val _ = debugmsg ">>matchIt"

      val (resultEntEnv, entDecs, absDecs, bindings, succeed) = 
	  matchElems(sigElements, entEnv, [], [], [], true)
	  handle EE.Unbound => (debugmsg "$matchIt 1"; raise EE.Unbound)
   in if succeed then
	let val resultEntEnv = EE.mark(mkStamp, resultEntEnv)
	    val _ = debugmsg "--matchIt: elements matched successfully"

	    val _ = checkSharing(specSig, resultEntEnv)
		    handle EE.Unbound => (debugmsg "$matchIt 3"; raise EE.Unbound)
	    val _ = debugmsg "--matchIt: sharing checked"

	    val resStr =
	      let val strEnt = {stamp = strStamp, entities = resultEntEnv, 
				lambdaty = ref NONE, rpath=rpath}
		  val dacc = DA.newAcc(mkv)
		  val dinfo = II.mkStrInfo (map MU.extractInfo bindings)
	       in M.STR{sign=specSig, rlzn=strEnt, access=dacc, info=dinfo}
	      end

	    val resDec = 
	      let val body = A.LETstr(A.SEQdec absDecs, A.STRstr bindings)
	       in A.STRdec [A.STRB{name=strName, str=resStr, def=body}]
	      end

	    val resExp = M.STRUCTURE{stamp = GETSTAMP(M.VARstr(rev epath)),
				     entDec = SEQdec(entDecs)}

	    val _ = debugmsg "<<matchIt"
	 in (resDec, resStr, resExp) 
	end
      else (A.SEQdec[],ERRORstr,M.CONSTstr(M.bogusStrEntity))
  end

in 

(* we should not do such short-cut matching because we need to
   recalculuate the tycpath information for functor components.
   But completely turning this off is a bit too expensive, so 
   we add a fctflag in the signature to indicate whether it 
   contains functor components. 
*)
    if (ST.eq(sigStamp, strSigStamp)) andalso closed andalso (not fctflag)
    then (A.SEQdec [], str, M.VARstr (rev epath))    (* short-cut matching *)
    else matchIt (if closed then EE.empty else matchEntEnv)
end 

| matchStr1 _ = (A.SEQdec [], ERRORstr, bogusStrExp)
(* end of matchStr1 *)


(***************************************************************************
 * val matchStr :                                                          *
 *                                                                         *
 *     {sign     : Modules.Signature,                                      *
 *      str      : Modules.Structure,                                      *
 *      strExp   : Modules.strExp,                                         *
 *      evOp     : EntPath.entVar,                                         * 
 *      depth    : DebIndex.depth,                                         *
 *      entEnv   : Modules.entityEnv,                                      *
 *      rpath    : InvPath.path,                                           *
 *      statenv  : StaticEnv.staticEnv,                                    *
 *      region   : SourceMap.region,                                       *
 *      compInfo : ElabUtil.compInfo} -> {resDec : Absyn.dec,              *
 *                                        resStr : Modules.Structure,      *
 *                                        resExp : Modules.strExp}         *
 *                                                                         *
 ***************************************************************************)
and matchStr {sign, str, strExp, evOp, depth, entEnv, rpath, statenv, region,
              compInfo=compInfo as {mkStamp,...}: EU.compInfo} =

  let val _ = debugmsg ">>matchStr"

      val uncoerced = case evOp of SOME x => x | NONE => mkStamp()
      val (resDec, resStr, exp) = 
        matchStr1 (sign, str, anonSym, depth, entEnv, [uncoerced], rpath, 
                   statenv, region, compInfo)

      val resExp = M.CONSTRAINstr{boundvar=uncoerced, raw=strExp, coercion=exp}
(*    val resExp = M.LETstr(M.STRdec(uncoerced, strExp), exp) *)
(*    val resExp = M.APPLY(M.LAMBDA{param=uncoerced, body=exp}, strExp) *)
      val _ = debugmsg "<<matchStr"

   in {resDec=resDec, resStr=resStr, resExp=resExp}
  end 
  handle EE.Unbound => (debugmsg "$matchStr"; raise EE.Unbound)


(***************************************************************************
 *                                                                         *
 * Matching a functor against a functor signature:                         *
 *                                                                         *
 *  val matchFct1 : fctSig * Functor * S.symbol * DI.depth *               *
 *                  entityEnv * M.fctExp * IP.path * staticEnv *           *
 *                  region * EU.compInfo                                   *
 *                  -> A.dec * M.Functor * M.fctExp                        *
 *                                                                         *
 *  Arguments: funsig  F(fsigParVar : fsigParSig) = fsigBodySig            *
 *             functor F(fctParVar : fctParSig) : fctBodySig = bodyExp     *
 *                                                                         *
 *  Result:    functor F(fctParVar : fctParSig) : fctBodySig = resBodyExp  *
 *                                                                         *
 ***************************************************************************)
and matchFct1(specSig as FSIG{paramsig=fsigParamSig,paramvar=fsigParamVar,
                              paramsym,bodysig=fsigBodySig,...},
              fct as FCT{rlzn=fctRlzn, ...}, fctName : S.symbol,
              depth, entEnv, uncoercedFct, rpath, statenv, region,
              compInfo as {mkStamp, mkLvar=mkv,...}: EU.compInfo)
              : A.dec * M.Functor * M.fctExp =
(let 

(*** the entity var for the source functor "uncoercedFct" *)
val uncoerced = mkStamp()
val srcFctExp = M.VARfct [uncoerced]
val paramSym = case paramsym of SOME x => x 
                              | NONE => paramSym

(*** parameter signature instantiation ***)
val {rlzn=fsigParEnt, tycpaths=paramTps} = 
  INS.instParam{sign=fsigParamSig, entEnv=entEnv, depth=depth,
                rpath=IP.IPATH[paramSym], region=region, compInfo=compInfo}

val depth'= DI.next depth
val fsigParInst = 
  let val fsigParDacc = DA.newAcc(mkv)
   in M.STR{sign=fsigParamSig, rlzn=fsigParEnt, 
            access=fsigParDacc, info=II.nullInfo}
  end

(*** applying fct to the fsigParInst structure ***)
val paramId = fsigParamVar (* mkStamp() *)
val {resDec=resDec1, resStr=resStr1, resExp=resExp1} = 
  let val paramExp = M.VARstr [paramId]
   in applyFct{fct=fct, fctExp=srcFctExp, argStr=fsigParInst, 
               argExp=paramExp, evOp=NONE, depth=depth', 
               epc=EPC.initContext (* ? ZHONG *), statenv=statenv, 
               rpath = IP.empty, region=region, compInfo=compInfo}
  end
          
(*** matching the result structure against the body sig ***) 
val fsigBodySigEnv = EE.bind(fsigParamVar, STRent fsigParEnt, entEnv)
val {resDec=resDec2, resStr=resStr2, resExp=resExp2} = 
  let val rp = IP.IPATH[S.strSymbol "<FctResult>"]
   in matchStr{sign=fsigBodySig, str=resStr1, strExp=resExp1, evOp=NONE,
               depth=depth', entEnv=fsigBodySigEnv, rpath=rp, 
               statenv=statenv, region=region, compInfo=compInfo}
  end

(*** constructing the tycpath for the resulting functor ***)
val resTps = 
  case resStr2 
   of M.STR{rlzn, sign, ...} => 
        INS.getTycPaths{sign=sign, rlzn=rlzn, entEnv=fsigBodySigEnv, 
                        compInfo=compInfo}
    | _ => []

(*** the resulting coerced functor ***)
val resFct =
  let val resExp3 = M.LETstr(M.FCTdec(uncoerced, M.CONSTfct fctRlzn), 
                             resExp2)
      val resClosure = CLOSURE{param=paramId, body=resExp3, env=entEnv}
      val tps = T.TP_FCT(paramTps, resTps)

      val resRlzn = {stamp = (#stamp fctRlzn), (*** DAVE ? ***)
                     closure = resClosure, rpath=rpath,
                     tycpath=SOME tps, lambdaty=ref NONE}

   in FCT{sign = specSig, rlzn = resRlzn,
          access = DA.newAcc(mkv), info = II.nullInfo}
  end

(*** the resulting functor absyn ***)
val fdec = 
  let val bodyAbs = A.LETstr(A.SEQdec [resDec1, resDec2], A.VARstr resStr2)
      val fctexp = A.FCTfct {param=fsigParInst, argtycs=paramTps, def=bodyAbs}
   in A.FCTdec [A.FCTB {name=anonFsym, fct=resFct, def=fctexp}]
  end

(*** the functor entity expression ***)
val fctExp = 
  M.LETfct(M.FCTdec(uncoerced, uncoercedFct), 
           M.LAMBDA_TP{param = paramId, body = resExp2, sign=specSig})

in 
   (fdec, resFct, fctExp)

end handle Match => (A.SEQdec [], ERRORfct, bogusFctExp))
     (* 
      * This is intended to handle only the two left-hand side 
      * occurrences of STR{ ... } above, and is very crude. 
      * It should be replaced by case-expressions on the results of 
      * match etc. 
      *)

| matchFct1 _ =  (A.SEQdec [], ERRORfct, bogusFctExp)


(***************************************************************************
 *                                                                         *
 * val matchFct :                                                          *
 *                                                                         *
 *     {sign     : Modules.fctSig,                                         *
 *      fct      : Modules.Functor,                                        *
 *      fctExp   : Modules.fctExp,                                         *
 *      depth    : DebIndex.depth,                                         *
 *      entEnv   : Modules.entityEnv,                                      *
 *      rpath    : InvPath.path,                                           *
 *      statenv  : StaticEnv.staticEnv,                                    *
 *      region   : SourceMap.region,                                       *
 *      compInfo : ElabUtil.compInfo} -> {resDec : Absyn.dec,              *
 *                                        resFct : Modules.Functor,        *
 *                                        resExp : Modules.fctExp}         *
 *                                                                         *
 ***************************************************************************)
and matchFct{sign, fct, fctExp, depth, entEnv, rpath, 
             statenv, region, compInfo} = 
  let val _ = debugmsg ">>matchFct"

      val (resDec, resFct, resExp) = 
        matchFct1 (sign, fct, anonFsym, depth, entEnv, fctExp, rpath, 
                   statenv, region, compInfo)

      val _ = debugmsg "<<matchFct"

   in {resDec=resDec, resFct=resFct, resExp=resExp}
  end 
  handle EE.Unbound => (debugmsg "$matchFct"; raise EE.Unbound)


(**************************************************************************
 *                                                                        *
 * Packing a structure against a signature:                               *
 *                                                                        *
 *  val packStr1 : Signature * strEntity * Structure * TU.tycset *        *
 *                 S.symbol * int * entityEnv * IP.path * staticEnv *     * 
 *                 region * EU.compInfo -> A.dec * M.Structure            *
 *                                                                        *
 **************************************************************************)
and packStr1(specSig as M.SIG {elements=sigElements, ...},
             resRlzn as {entities=resEntEnv, ...},
             str as M.STR {rlzn=srcRlzn as {entities=srcEntEnv, ...},
                           access=rootAcc, info=rootInfo, ...},
             abstycs, strName, depth, entEnv, rpath, statenv, region, 
             compInfo as {mkLvar=mkv, error, ...}: EU.compInfo) 
             : Absyn.dec * M.Structure = 

let 

fun typeInRes (kind,typ) = 
      (MU.transType resEntEnv typ) 
         handle EE.Unbound => 
           (debugPrint (debugging) (kind, PPType.ppType statenv, typ);
            raise EE.Unbound)

fun typeInSrc (kind,typ) = 
      (MU.transType srcEntEnv typ) 
         handle EE.Unbound => 
           (debugPrint (debugging) (kind, PPType.ppType statenv, typ);
            raise EE.Unbound)

fun packElems ([], entEnv, decs, bindings) = (rev decs, rev bindings)
  | packElems ((sym, spec) :: elems, entEnv, decs, bindings) = 
     let val _ = debugmsg ">>packElems"
      in case spec
          of STRspec{sign=thisSpecsig, entVar=ev, slot=s,...} =>
              (case (EE.look(resEntEnv, ev), EE.look(srcEntEnv, ev))  
                 of (M.STRent resStrRlzn, M.STRent srcStrRlzn) =>
		     let val srcStr = M.STR{sign=thisSpecsig, rlzn=srcStrRlzn,
					    access=DA.selAcc(rootAcc,s),
					    info=II.selInfo(rootInfo,s)}

			 val rpath' = IP.extend(rpath, sym)
			 val (thinDec, thinStr) = 
			   packStr1(thisSpecsig, resStrRlzn, srcStr, abstycs,
				    sym, depth, entEnv, rpath', statenv, 
				    region, compInfo)

                         val entEnv' = 
                           let val strEnt = 
                                case thinStr of M.STR{rlzn, ...} => rlzn
                                              | _ => M.bogusStrEntity
                            in EE.bind(ev, M.STRent strEnt, entEnv)
                           end

			 val decs' = thinDec :: decs
			 val bindings' = (B.STRbind thinStr) :: bindings

		      in packElems(elems, entEnv', decs', bindings')
		     end
	          | _ => (* missing element, error has occurred - do nothing *)
		    packElems(elems, entEnv, decs, bindings))

           | FCTspec{sign=thisSpecsig, entVar=ev, slot=s} => 
              (case (EE.look(resEntEnv, ev), EE.look(srcEntEnv, ev))
		 of (M.FCTent resFctRlzn, M.FCTent srcFctRlzn) =>
		     let val srcFct = M.FCT{sign=thisSpecsig, rlzn=srcFctRlzn,
					    access=DA.selAcc(rootAcc,s),
					    info=II.selInfo(rootInfo,s)}  

			 val rpath' = IP.extend(rpath, sym)

			 val (thinDec, thinFct) = 
			   packFct1(thisSpecsig, resFctRlzn, srcFct, abstycs,
				    sym, depth, entEnv, rpath', statenv,
				    region, compInfo)

                         val entEnv' = 
                           let val fctEnt = 
                                 case thinFct of M.FCT{rlzn, ...} => rlzn
                                               | _ => M.bogusFctEntity
                            in EE.bind(ev, M.FCTent fctEnt, entEnv)
                           end

			 val decs' = thinDec :: decs
			 val bindings' = (B.FCTbind thinFct) :: bindings

		      in packElems(elems, entEnv', decs', bindings')
		     end
		  | _ => packElems(elems, entEnv, decs, bindings))

           | VALspec{spec=spectyp, slot=s} => 
              (let val restyp = typeInRes("$spec-resty(packStr-val)", spectyp)
                   val srctyp = typeInSrc("$spec-srcty(packStr-val)", spectyp)
                   val dacc = DA.selAcc(rootAcc, s)
                   val dinfo = II.selInfo(rootInfo, s)
                   val (instys, btvs, resinst, eqflag) = 
                     absEqvTy(restyp, srctyp, dinfo)

                   val spath = SP.SPATH[sym]
                   val srcvar = VALvar{path=spath, typ=ref srctyp,
                                       access=dacc, info=dinfo}

                   val (decs', nv) =
                     if eqflag then (decs, srcvar)
                     else (let val acc = DA.namedAcc(sym, mkv)
                               val resvar = 
                                 VALvar{path=spath, typ=ref restyp,
                                        access=acc, info=II.nullInfo}

                               val ntycs = TU.filterSet(resinst, abstycs)
                               val exp = 
                                 A.PACKexp(A.VARexp(ref srcvar, instys),
                                           resinst, ntycs)

                               val vb = A.VB {pat=(A.VARpat resvar), exp=exp,
                                              boundtvs=btvs, tyvars=ref []}

                            in ((A.VALdec [vb])::decs, resvar)
                           end)


                   val bindings' = (B.VALbind nv)::bindings
                in packElems(elems, entEnv, decs', bindings')
               end)

           | CONspec{spec=DATACON{name, typ, rep, const, sign, lazyp}, slot} =>
              (let val bindings' =
                     case slot 
                      of NONE => bindings 
                       | SOME s => 
                           let val restyp = 
                                 typeInRes("$spec-resty(packStr-con)", typ)
                               val dacc = DA.selAcc(rootAcc, s)
                               val nrep = exnRep(rep, dacc) 
                               val con = DATACON{typ=restyp, name=name, lazyp=lazyp,
                                           const=const, rep=nrep, sign=sign}
                            in (B.CONbind(con)) :: bindings
                           end

                in packElems(elems, entEnv, decs, bindings')
               end)

           | TYCspec{spec=specTycon,entVar=ev,scope} =>
              (let val entEnv' = EE.bind(ev, EE.look(resEntEnv, ev), entEnv) 
                in packElems(elems, entEnv', decs, bindings)
               end)

     end (* function packElems *)


val (absDecs, bindings) = packElems(sigElements, entEnv, [], [])       

val resStr =
  let val dacc = DA.newAcc(mkv)
      val dinfo = II.mkStrInfo (map MU.extractInfo bindings)
   in M.STR{sign=specSig, rlzn=resRlzn, access=dacc, info=dinfo}
  end

val resDec = 
  let val body = A.LETstr(A.SEQdec absDecs, A.STRstr bindings)
   in A.STRdec [A.STRB{name=strName, str=resStr, def=body}]
  end

in (resDec, resStr)
end 

| packStr1 _ = (A.SEQdec [], ERRORstr)


(***************************************************************************
 * Abstraction matching of a structure against a signature:                *
 *                                                                         *
 * val packStr :                                                           *
 *     {sign     : Modules.Signature,                                      * 
 *      str      : Modules.Structure,                                      * 
 *      strExp   : Modules.strExp,                                         *
 *      depth    : DebIndex.depth,                                         *
 *      entEnv   : Modules.entityEnv,                                      * 
 *      rpath    : InvPath.path,                                           * 
 *      statenv  : StaticEnv.staticEnv,                                    * 
 *      region   : SourceMap.region,                                       * 
 *      compInfo : ElabUtil.compInfo} -> {resDec : Absyn.dec,              *
 *                                        resStr : Modules.Structure,      *
 *                                        resExp : Modules.strExp}         *
 *                                                                         *
 * INVARIANT: the base signature for str should be exactly sign; in other  *
 *            words, str should have been matched against sign before it   *
 *            being packed against sign.                                   *
 ***************************************************************************)
and packStr {sign, str, strExp, depth, entEnv, rpath, 
             statenv, region, compInfo} = 
  let val _ = debugmsg ">>>packStr"

      val {rlzn=resRlzn, abstycs=abstycs, tyceps=_} = 
        let val srcRlzn = case str of M.STR{rlzn, ...} => rlzn
                                    | _ => M.bogusStrEntity
         in INS.instAbstr {sign=sign, entEnv=entEnv, srcRlzn=srcRlzn,
                           rpath=rpath, region=region, compInfo=compInfo}
        end
      val _ = debugmsg "packStr - instantiate done"

      val abstycs' = foldr TU.addTycSet (TU.mkTycSet()) abstycs

      val (resDec, resStr) = 
        packStr1 (sign, resRlzn, str, abstycs', anonSym, depth,
                  entEnv, rpath, statenv, region, compInfo)
      val _ = debugmsg "packStr - packStr1 done"

      val resExp = M.ABSstr(sign, strExp)
      val _ = debugmsg "<<<packStr"

   in {resDec=resDec, resStr=resStr, resExp=resExp}
  end 


(***************************************************************************
 *                                                                         *
 * Packing a functor against a functor signature:                          *
 *                                                                         *
 *  val packFct1 : fctSig * fctEntity * Functor * tycon list *             *
 *                 S.symbol * DI.depth * entityEnv * IP.path * staticEnv * *
 *                 region * EU.compInfo -> A.dec * M.Functor               *
 *                                                                         *
 ***************************************************************************)
and packFct1(specSig as FSIG{paramsig, paramvar, bodysig, ...}, resFctRlzn,
             srcFct as FCT {rlzn=srcFctRlzn, ...},
             abstycs1, fctName, depth, entEnv, rpath, statenv, region,
             compInfo as {mkStamp, mkLvar=mkv, error, ...}: EU.compInfo)
             : Absyn.dec * M.Functor = 

let

val {rlzn=paramEnt, tycpaths=paramTps} = 
  INS.instParam{sign=paramsig, entEnv=entEnv, depth=depth,
                rpath=IP.IPATH[paramSym], region=region, compInfo=compInfo}

val depth'= DI.next depth
val paramStr = 
  let val paramDacc = DA.newAcc(mkv)
   in M.STR{sign=paramsig, rlzn=paramEnt, access=paramDacc, info=II.nullInfo}
  end

val {resDec=rdec1, resStr=bodyStr, resExp=_} =
  applyFct{fct=srcFct, fctExp=CONSTfct srcFctRlzn, argStr=paramStr, 
           argExp=CONSTstr paramEnt, evOp=NONE, depth=depth', 
           epc=EPC.initContext (* ? ZHONG *), statenv=statenv, 
           rpath=IP.empty, region=region, compInfo=compInfo}

(* val bodyRlzn = EV.evalApp(srcFctRlzn, paramEnt, depth', epc, compInfo) *)
val bodyRlzn = 
  case bodyStr of M.STR {rlzn, ...} => rlzn
                | _ => M.bogusStrEntity

val {rlzn=resRlzn, abstycs=abstycs2, tyceps=_} = 
  let val entEnv' = 
        EE.mark(mkStamp, EE.bind(paramvar, STRent paramEnt, entEnv))
   in INS.instAbstr {sign=bodysig, entEnv=entEnv', srcRlzn=bodyRlzn,
                     rpath=rpath, region=region, compInfo=compInfo}
  end

val abstycs = foldr TU.addTycSet abstycs1 abstycs2

val (rdec2, resStr) = 
  let val rpath' = IP.IPATH[S.strSymbol "<FctResult>"]
   in packStr1(bodysig, resRlzn, bodyStr, abstycs, anonSym,
               depth', entEnv, rpath', statenv, region, compInfo)
  end

val resFct = 
  let val resDacc = DA.newAcc(mkv)
   in M.FCT{sign=specSig, rlzn=resFctRlzn, access=resDacc, info=II.nullInfo}
  end

val resDec = 
  let val body = A.LETstr(rdec1, A.LETstr(rdec2, A.VARstr resStr))
      val fctexp = A.FCTfct{param=paramStr, argtycs=paramTps, def=body}
   in A.FCTdec [A.FCTB {name=fctName, fct=resFct, def=fctexp}]
  end

in (resDec, resFct)

end (* function packFct1 *)

| packFct1 _ =  (A.SEQdec [], ERRORfct)


(***************************************************************************
 * val applyFct :                                                          *
 *                                                                         *
 *     {fct      : Modules.Functor,                                        *
 *      fctExp   : Modules.fctExp,                                         *
 *      argStr   : Modules.Structure,                                      *
 *      argExp   : Modules.strExp,                                         *
 *      evOp     : EntPath.entVar option,                                  *
 *      depth    : DebIndex.depth,                                         *
 *      epc      : EntPathContext.context,                                 *
 *      statenv  : StaticEnv.staticEnv,                                    *
 *      rpath    : InvPath.path,                                           *
 *      region   : SourceMap.region,                                       *
 *      compInfo : ElabUtil.compInfo} -> {resDec : Absyn.dec,              *
 *                                        resStr : Modules.Structure,      *
 *                                        resExp : Modules.strExp}         *
 *                                                                         *
 * Matches and coerces the argument and then do the functor application.   *
 * Returns the result structure, the result entity expression, and the     *
 * result abstract syntax declaration of resStr.                           *
 *                                                                         *
 * The argument matching takes place in the entityEnv stored in the        *
 * functor closure; this is where the paramsig must be interpreted.        *
 *                                                                         *
 ***************************************************************************)
and applyFct{fct as FCT{sign=FSIG{paramsig, bodysig, ...}, 
                        rlzn = fctRlzn as {closure=CLOSURE{env=fctEntEnv,  
                                                           ...}, ...},
                          ...},
             fctExp, argStr, argExp, evOp, epc, depth, statenv, rpath, region,
             compInfo as {mkStamp, mkLvar=mkv, ...}} = 

  let val _ = debugmsg ">>applyFct"

      (*** step #1: match the argument structure against paramSig ***)
      val {resDec=argDec1, resStr=argStr1, resExp=argExp1} =  
        matchStr {sign=paramsig, str=argStr, strExp=argExp, evOp=evOp, 
                  depth=depth, entEnv=fctEntEnv, rpath=IP.IPATH[] (* ?DAVE *), 
                  statenv=statenv, region=region, compInfo=compInfo}

      (*** step #2: do the functor application ***)
      val argRlzn = case argStr1 of M.STR{rlzn, ...} => rlzn
                                  | _ => M.bogusStrEntity 
      val bodyRlzn = EV.evalApp(fctRlzn, argRlzn, depth, epc, rpath, compInfo)
      val resStr = 
        let val bodyDacc = DA.namedAcc(anonSym,mkv)
         in M.STR {sign=bodysig, rlzn=bodyRlzn, 
                   access=bodyDacc, info=II.nullInfo}
        end

      val resDec = 
        let val argtycs = INS.getTycPaths{sign=paramsig, rlzn=argRlzn, 
                                          entEnv=fctEntEnv, compInfo=compInfo}
            val body = A.APPstr{oper=fct, arg=argStr1, argtycs=argtycs}
            val resAbs = A.LETstr(argDec1, body)

         in A.STRdec [A.STRB{name=anonSym, str=resStr, def=resAbs}]
        end

      val resExp = M.APPLY(fctExp, argExp1)
      val _ = debugmsg "<<applyFct"

   in {resDec=resDec, resStr=resStr, resExp=resExp}
  end

  | applyFct {fct=ERRORfct, ...} = 
      {resDec=A.STRdec [], resStr=M.ERRORstr, 
       resExp=M.CONSTstr M.bogusStrEntity}
  | applyFct _ = bug "unexpected case in applyFct"


(*** top leve wrappers: used for profiling the compilation time *)
(*
val matchStr = 
  Stats.doPhase (Stats.makePhase "Compiler 034 1-matchStr") matchStr

val matchFct = 
  Stats.doPhase (Stats.makePhase "Compiler 034 2-matchFct") matchFct

val packStr = 
  Stats.doPhase (Stats.makePhase "Compiler 034 3-packStr") packStr

val applyFct = 
  Stats.doPhase (Stats.makePhase "Compiler 034 4-applyFct") applyFct
*)

end (* local *)
end (* structure SigMatch *)


(*
 * $Log$
 *)