Dafny: added assign-such-that statements; syntax: x,y,a[i],o.f :| Expr;

12 files changed, 837 insertions, 567 deletions

diff --git a/Dafny/Compiler.cs b/Dafny/Compiler.cs
index d5b15300..454b47be 100644
--- a/Dafny/Compiler.cs
+++ b/Dafny/Compiler.cs
@@ -710,40 +710,11 @@ namespace Microsoft.Dafny {
       Contract.Requires(stmt != null);

       if (stmt is AssumeStmt) {

         Error("an assume statement cannot be compiled (line {0})", stmt.Tok.line);

-      } else if (stmt is BlockStmt) {

-        foreach (Statement s in ((BlockStmt)stmt).Body) {

-          CheckHasNoAssumes(s);

-        }

-      } else if (stmt is IfStmt) {

-        IfStmt s = (IfStmt)stmt;

-        CheckHasNoAssumes(s.Thn);

-        if (s.Els != null) {

-          CheckHasNoAssumes(s.Els);

-        }

-      } else if (stmt is AlternativeStmt) {

-        foreach (var alternative in ((AlternativeStmt)stmt).Alternatives) {

-          foreach (Statement s in alternative.Body) {

-            CheckHasNoAssumes(s);

-          }

-        }

-      } else if (stmt is WhileStmt) {

-        WhileStmt s = (WhileStmt)stmt;

-        CheckHasNoAssumes(s.Body);

-      } else if (stmt is AlternativeLoopStmt) {

-        foreach (var alternative in ((AlternativeLoopStmt)stmt).Alternatives) {

-          foreach (Statement s in alternative.Body) {

-            CheckHasNoAssumes(s);

-          }

-        }

-      } else if (stmt is ParallelStmt) {

-        var s = (ParallelStmt)stmt;

-        CheckHasNoAssumes(s.Body);

-      } else if (stmt is MatchStmt) {

-        MatchStmt s = (MatchStmt)stmt;

-        foreach (MatchCaseStmt mc in s.Cases) {

-          foreach (Statement bs in mc.Body) {

-            CheckHasNoAssumes(bs);

-          }

+      } else if (stmt is AssignSuchThatStmt) {

+        Error("an assign-such-that statement cannot be compiled (line {0})", stmt.Tok.line);

+      } else {

+        foreach (var ss in stmt.SubStatements) {

+          CheckHasNoAssumes(ss);

         }

       }

     }

diff --git a/Dafny/Dafny.atg b/Dafny/Dafny.atg
index 740926e5..c6609b4c 100644
--- a/Dafny/Dafny.atg
+++ b/Dafny/Dafny.atg
@@ -712,6 +712,7 @@ UpdateStmt<out Statement/*!*/ s>
      Expression lhs0;

      IToken x;

      Attributes attrs = null;

+     Expression suchThat = null;

   .)

   Lhs<out e>                       (. x = e.tok; .)

   ( { Attribute<ref attrs> }

@@ -719,14 +720,22 @@ UpdateStmt<out Statement/*!*/ s>
   |                                (. lhss.Add(e);  lhs0 = e; .)

     { "," Lhs<out e>               (. lhss.Add(e); .)

     }

-    ":="                           (. x = t; .)

-    Rhs<out r, lhs0>               (. rhss.Add(r); .)

-    { "," Rhs<out r, lhs0>         (. rhss.Add(r); .)

-    }

+    ( ":="                         (. x = t; .)

+      Rhs<out r, lhs0>             (. rhss.Add(r); .)

+      { "," Rhs<out r, lhs0>       (. rhss.Add(r); .)

+      }

+    | ":|"                         (. x = t; .)

+      Expression<out suchThat>

+    )

     ";"

   | ":"                            (. SemErr(t, "invalid statement (did you forget the 'label' keyword?)"); .)

   )

-  (. s = new UpdateStmt(x, lhss, rhss); .)

+  (. if (suchThat != null) {

+       s = new AssignSuchThatStmt(x, lhss, suchThat);

+     } else {

+       s = new UpdateStmt(x, lhss, rhss);

+     }

+  .)

   .

 Rhs<out AssignmentRhs r, Expression receiverForInitCall>

 = (. IToken/*!*/ x, newToken;  Expression/*!*/ e;

@@ -770,6 +779,7 @@ VarDeclStatement<.out Statement/*!*/ s.>
      AssignmentRhs r;  IdentifierExpr lhs0;

      List<VarDecl> lhss = new List<VarDecl>();

      List<AssignmentRhs> rhss = new List<AssignmentRhs>();

+     Expression suchThat = null;

   .)

   [ "ghost"                                 (. isGhost = true;  x = t; .)

   ]

@@ -785,10 +795,18 @@ VarDeclStatement<.out Statement/*!*/ s.>
     Rhs<out r, lhs0>               (. rhss.Add(r); .)

     { "," Rhs<out r, lhs0>         (. rhss.Add(r); .)

     }

+  | ":|"                           (. assignTok = t; .)

+    Expression<out suchThat>

   ]

   ";"

-  (. UpdateStmt update;

-     if (rhss.Count == 0) {

+  (. ConcreteUpdateStatement update;

+     if (suchThat != null) {

+       var ies = new List<Expression>();

+       foreach (var lhs in lhss) {

+         ies.Add(new IdentifierExpr(lhs.Tok, lhs.Name));

+       }

+       update = new AssignSuchThatStmt(assignTok, ies, suchThat);

+     } else if (rhss.Count == 0) {

        update = null;

      } else {

        var ies = new List<Expression>();

diff --git a/Dafny/DafnyAst.cs b/Dafny/DafnyAst.cs
index 407966bb..f5955d11 100644
--- a/Dafny/DafnyAst.cs
+++ b/Dafny/DafnyAst.cs
@@ -1562,13 +1562,13 @@ namespace Microsoft.Dafny {
   public class VarDeclStmt : ConcreteSyntaxStatement

   {

     public readonly List<VarDecl> Lhss;

-    public readonly UpdateStmt Update;

+    public readonly ConcreteUpdateStatement Update;

     [ContractInvariantMethod]

     void ObjectInvariant() {

       Contract.Invariant(cce.NonNullElements(Lhss));

     }

 

-    public VarDeclStmt(IToken tok, List<VarDecl> lhss, UpdateStmt update)

+    public VarDeclStmt(IToken tok, List<VarDecl> lhss, ConcreteUpdateStatement update)

       : base(tok)

     {

       Contract.Requires(lhss != null);

@@ -1578,9 +1578,35 @@ namespace Microsoft.Dafny {
     }

   }

 

-  public class UpdateStmt : ConcreteSyntaxStatement

+  /// <summary>

+  /// Common superclass of UpdateStmt and AssignSuchThatStmt.

+  /// </summary>

+  public abstract class ConcreteUpdateStatement : ConcreteSyntaxStatement

   {

     public readonly List<Expression> Lhss;

+    public ConcreteUpdateStatement(IToken tok, List<Expression> lhss)

+      : base(tok) {

+      Contract.Requires(tok != null);

+      Contract.Requires(cce.NonNullElements(lhss));

+      Lhss = lhss;

+    }

+  }

+

+  public class AssignSuchThatStmt : ConcreteUpdateStatement

+  {

+    public readonly AssumeStmt Assume;

+    public AssignSuchThatStmt(IToken tok, List<Expression> lhss, Expression expr)

+      : base(tok, lhss) {

+      Contract.Requires(tok != null);

+      Contract.Requires(cce.NonNullElements(lhss));

+      Contract.Requires(lhss.Count != 0);

+      Contract.Requires(expr != null);

+      Assume = new AssumeStmt(tok, expr);

+    }

+  }

+

+  public class UpdateStmt : ConcreteUpdateStatement

+  {

     public readonly List<AssignmentRhs> Rhss;

     public readonly bool CanMutateKnownState;

     [ContractInvariantMethod]

@@ -1589,24 +1615,22 @@ namespace Microsoft.Dafny {
       Contract.Invariant(cce.NonNullElements(Rhss));

     }

     public UpdateStmt(IToken tok, List<Expression> lhss, List<AssignmentRhs> rhss)

-      : base(tok)

+      : base(tok, lhss)

     {

       Contract.Requires(tok != null);

       Contract.Requires(cce.NonNullElements(lhss));

       Contract.Requires(cce.NonNullElements(rhss));

       Contract.Requires(lhss.Count != 0 || rhss.Count == 1);

-      Lhss = lhss;

       Rhss = rhss;

       CanMutateKnownState = false;

     }

     public UpdateStmt(IToken tok, List<Expression> lhss, List<AssignmentRhs> rhss, bool mutate)

-      : base(tok)

+      : base(tok, lhss)

     {

       Contract.Requires(tok != null);

       Contract.Requires(cce.NonNullElements(lhss));

       Contract.Requires(cce.NonNullElements(rhss));

       Contract.Requires(lhss.Count != 0 || rhss.Count == 1);

-      Lhss = lhss;

       Rhss = rhss;

       CanMutateKnownState = mutate;

     }

diff --git a/Dafny/Parser.cs b/Dafny/Parser.cs
index bf7d1fe1..8e0d2e31 100644
--- a/Dafny/Parser.cs
+++ b/Dafny/Parser.cs
@@ -21,7 +21,7 @@ public class Parser {
 	public const int _colon = 5;

 	public const int _lbrace = 6;

 	public const int _rbrace = 7;

-	public const int maxT = 105;

+	public const int maxT = 106;

 

 	const bool T = true;

 	const bool x = false;

@@ -259,7 +259,7 @@ bool IsAttribute() {
 				defaultModule.TopLevelDecls.Add(at); 

 			} else if (StartOf(3)) {

 				ClassMemberDecl(membersDefaultClass, isGhost, false);

-			} else SynErr(106);

+			} else SynErr(107);

 		}

 		if (defaultModuleCreatedHere) {

 		 defaultModule.TopLevelDecls.Add(new DefaultClassDecl(defaultModule, membersDefaultClass));

@@ -310,7 +310,7 @@ bool IsAttribute() {
 		List<MemberDecl/*!*/> members = new List<MemberDecl/*!*/>();

 		IToken bodyStart;

 		

-		while (!(la.kind == 0 || la.kind == 12)) {SynErr(107); Get();}

+		while (!(la.kind == 0 || la.kind == 12)) {SynErr(108); Get();}

 		Expect(12);

 		while (la.kind == 6) {

 			Attribute(ref attrs);

@@ -340,7 +340,7 @@ bool IsAttribute() {
 		List<DatatypeCtor/*!*/> ctors = new List<DatatypeCtor/*!*/>();

 		IToken bodyStart = Token.NoToken;  // dummy assignment

 		

-		while (!(la.kind == 0 || la.kind == 15)) {SynErr(108); Get();}

+		while (!(la.kind == 0 || la.kind == 15)) {SynErr(109); Get();}

 		Expect(15);

 		while (la.kind == 6) {

 			Attribute(ref attrs);

@@ -356,7 +356,7 @@ bool IsAttribute() {
 			Get();

 			DatatypeMemberDecl(ctors);

 		}

-		while (!(la.kind == 0 || la.kind == 18)) {SynErr(109); Get();}

+		while (!(la.kind == 0 || la.kind == 18)) {SynErr(110); Get();}

 		Expect(18);

 		dt = new DatatypeDecl(id, id.val, module, typeArgs, ctors, attrs);

 		dt.BodyStartTok = bodyStart;

@@ -374,7 +374,7 @@ bool IsAttribute() {
 		}

 		Ident(out id);

 		at = new ArbitraryTypeDecl(id, id.val, module, attrs); 

-		while (!(la.kind == 0 || la.kind == 18)) {SynErr(110); Get();}

+		while (!(la.kind == 0 || la.kind == 18)) {SynErr(111); Get();}

 		Expect(18);

 	}

 

@@ -405,7 +405,7 @@ bool IsAttribute() {
 		} else if (la.kind == 24 || la.kind == 25) {

 			MethodDecl(mmod, allowConstructors, out m);

 			mm.Add(m); 

-		} else SynErr(111);

+		} else SynErr(112);

 	}

 

 	void GenericParameters(List<TypeParameter/*!*/>/*!*/ typeArgs) {

@@ -427,7 +427,7 @@ bool IsAttribute() {
 		Attributes attrs = null;

 		IToken/*!*/ id;  Type/*!*/ ty;

 		

-		while (!(la.kind == 0 || la.kind == 19)) {SynErr(112); Get();}

+		while (!(la.kind == 0 || la.kind == 19)) {SynErr(113); Get();}

 		Expect(19);

 		if (mmod.IsUnlimited) { SemErr(t, "fields cannot be declared 'unlimited'"); }

 		if (mmod.IsStatic) { SemErr(t, "fields cannot be declared 'static'"); }

@@ -442,7 +442,7 @@ bool IsAttribute() {
 			IdentType(out id, out ty);

 			mm.Add(new Field(id, id.val, mmod.IsGhost, ty, attrs)); 

 		}

-		while (!(la.kind == 0 || la.kind == 18)) {SynErr(113); Get();}

+		while (!(la.kind == 0 || la.kind == 18)) {SynErr(114); Get();}

 		Expect(18);

 	}

 

@@ -488,7 +488,7 @@ bool IsAttribute() {
 				Get();

 				signatureOmitted = true;

 				openParen = Token.NoToken; 

-			} else SynErr(114);

+			} else SynErr(115);

 		} else if (la.kind == 43) {

 			Get();

 			isPredicate = true; 

@@ -517,8 +517,8 @@ bool IsAttribute() {
 				Get();

 				signatureOmitted = true;

 				openParen = Token.NoToken; 

-			} else SynErr(115);

-		} else SynErr(116);

+			} else SynErr(116);

+		} else SynErr(117);

 		while (StartOf(5)) {

 			FunctionSpec(reqs, reads, ens, decreases);

 		}

@@ -557,7 +557,7 @@ bool IsAttribute() {
 		IToken bodyStart = Token.NoToken;

 		IToken bodyEnd = Token.NoToken;

 		

-		while (!(la.kind == 0 || la.kind == 24 || la.kind == 25)) {SynErr(117); Get();}

+		while (!(la.kind == 0 || la.kind == 24 || la.kind == 25)) {SynErr(118); Get();}

 		if (la.kind == 24) {

 			Get();

 		} else if (la.kind == 25) {

@@ -568,7 +568,7 @@ bool IsAttribute() {
 			 SemErr(t, "constructors are only allowed in classes");

 			}

 			

-		} else SynErr(118);

+		} else SynErr(119);

 		if (mmod.IsUnlimited) { SemErr(t, "methods cannot be declared 'unlimited'"); }

 		if (isConstructor) {

 		 if (mmod.IsGhost) {

@@ -596,7 +596,7 @@ bool IsAttribute() {
 		} else if (la.kind == 27) {

 			Get();

 			signatureOmitted = true; openParen = Token.NoToken; 

-		} else SynErr(119);

+		} else SynErr(120);

 		while (StartOf(6)) {

 			MethodSpec(req, mod, ens, dec, ref decAttrs, ref modAttrs);

 		}

@@ -779,7 +779,7 @@ bool IsAttribute() {
 			ReferenceType(out tok, out ty);

 			break;

 		}

-		default: SynErr(120); break;

+		default: SynErr(121); break;

 		}

 	}

 

@@ -804,7 +804,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		Contract.Requires(cce.NonNullElements(req)); Contract.Requires(cce.NonNullElements(mod)); Contract.Requires(cce.NonNullElements(ens)); Contract.Requires(cce.NonNullElements(decreases));

 		Expression/*!*/ e;  FrameExpression/*!*/ fe;  bool isFree = false; Attributes ensAttrs = null;

 		

-		while (!(StartOf(8))) {SynErr(121); Get();}

+		while (!(StartOf(8))) {SynErr(122); Get();}

 		if (la.kind == 28) {

 			Get();

 			while (IsAttribute()) {

@@ -819,7 +819,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 					mod.Add(fe); 

 				}

 			}

-			while (!(la.kind == 0 || la.kind == 18)) {SynErr(122); Get();}

+			while (!(la.kind == 0 || la.kind == 18)) {SynErr(123); Get();}

 			Expect(18);

 		} else if (la.kind == 29 || la.kind == 30 || la.kind == 31) {

 			if (la.kind == 29) {

@@ -829,7 +829,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			if (la.kind == 30) {

 				Get();

 				Expression(out e);

-				while (!(la.kind == 0 || la.kind == 18)) {SynErr(123); Get();}

+				while (!(la.kind == 0 || la.kind == 18)) {SynErr(124); Get();}

 				Expect(18);

 				req.Add(new MaybeFreeExpression(e, isFree)); 

 			} else if (la.kind == 31) {

@@ -838,19 +838,19 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 					Attribute(ref ensAttrs);

 				}

 				Expression(out e);

-				while (!(la.kind == 0 || la.kind == 18)) {SynErr(124); Get();}

+				while (!(la.kind == 0 || la.kind == 18)) {SynErr(125); Get();}

 				Expect(18);

 				ens.Add(new MaybeFreeExpression(e, isFree, ensAttrs)); 

-			} else SynErr(125);

+			} else SynErr(126);

 		} else if (la.kind == 32) {

 			Get();

 			while (IsAttribute()) {

 				Attribute(ref decAttrs);

 			}

 			DecreasesList(decreases, false);

-			while (!(la.kind == 0 || la.kind == 18)) {SynErr(126); Get();}

+			while (!(la.kind == 0 || la.kind == 18)) {SynErr(127); Get();}

 			Expect(18);

-		} else SynErr(127);

+		} else SynErr(128);

 	}

 

 	void BlockStmt(out BlockStmt/*!*/ block, out IToken bodyStart, out IToken bodyEnd) {

@@ -944,17 +944,17 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 				GenericInstantiation(gt);

 			}

 			ty = new UserDefinedType(tok, tok.val, gt); 

-		} else SynErr(128);

+		} else SynErr(129);

 	}

 

 	void FunctionSpec(List<Expression/*!*/>/*!*/ reqs, List<FrameExpression/*!*/>/*!*/ reads, List<Expression/*!*/>/*!*/ ens, List<Expression/*!*/>/*!*/ decreases) {

 		Contract.Requires(cce.NonNullElements(reqs)); Contract.Requires(cce.NonNullElements(reads)); Contract.Requires(cce.NonNullElements(decreases));

 		Expression/*!*/ e;  FrameExpression/*!*/ fe; 

 		if (la.kind == 30) {

-			while (!(la.kind == 0 || la.kind == 30)) {SynErr(129); Get();}

+			while (!(la.kind == 0 || la.kind == 30)) {SynErr(130); Get();}

 			Get();

 			Expression(out e);

-			while (!(la.kind == 0 || la.kind == 18)) {SynErr(130); Get();}

+			while (!(la.kind == 0 || la.kind == 18)) {SynErr(131); Get();}

 			Expect(18);

 			reqs.Add(e); 

 		} else if (la.kind == 44) {

@@ -968,20 +968,20 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 					reads.Add(fe); 

 				}

 			}

-			while (!(la.kind == 0 || la.kind == 18)) {SynErr(131); Get();}

+			while (!(la.kind == 0 || la.kind == 18)) {SynErr(132); Get();}

 			Expect(18);

 		} else if (la.kind == 31) {

 			Get();

 			Expression(out e);

-			while (!(la.kind == 0 || la.kind == 18)) {SynErr(132); Get();}

+			while (!(la.kind == 0 || la.kind == 18)) {SynErr(133); Get();}

 			Expect(18);

 			ens.Add(e); 

 		} else if (la.kind == 32) {

 			Get();

 			DecreasesList(decreases, false);

-			while (!(la.kind == 0 || la.kind == 18)) {SynErr(133); Get();}

+			while (!(la.kind == 0 || la.kind == 18)) {SynErr(134); Get();}

 			Expect(18);

-		} else SynErr(134);

+		} else SynErr(135);

 	}

 

 	void FunctionBody(out Expression/*!*/ e, out IToken bodyStart, out IToken bodyEnd) {

@@ -1000,7 +1000,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			fe = new FrameExpression(new WildcardExpr(t), null); 

 		} else if (StartOf(9)) {

 			FrameExpression(out fe);

-		} else SynErr(135);

+		} else SynErr(136);

 	}

 

 	void PossiblyWildExpression(out Expression/*!*/ e) {

@@ -1011,7 +1011,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			e = new WildcardExpr(t); 

 		} else if (StartOf(9)) {

 			Expression(out e);

-		} else SynErr(136);

+		} else SynErr(137);

 	}

 

 	void Stmt(List<Statement/*!*/>/*!*/ ss) {

@@ -1028,26 +1028,26 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		IToken bodyStart, bodyEnd;

 		int breakCount;

 		

-		while (!(StartOf(12))) {SynErr(137); Get();}

+		while (!(StartOf(12))) {SynErr(138); Get();}

 		switch (la.kind) {

 		case 6: {

 			BlockStmt(out bs, out bodyStart, out bodyEnd);

 			s = bs; 

 			break;

 		}

-		case 63: {

+		case 64: {

 			AssertStmt(out s);

 			break;

 		}

-		case 64: {

+		case 65: {

 			AssumeStmt(out s);

 			break;

 		}

-		case 65: {

+		case 66: {

 			PrintStmt(out s);

 			break;

 		}

-		case 1: case 2: case 17: case 33: case 90: case 91: case 92: case 93: case 94: case 95: case 96: {

+		case 1: case 2: case 17: case 33: case 91: case 92: case 93: case 94: case 95: case 96: case 97: {

 			UpdateStmt(out s);

 			break;

 		}

@@ -1055,19 +1055,19 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			VarDeclStatement(out s);

 			break;

 		}

-		case 56: {

+		case 57: {

 			IfStmt(out s);

 			break;

 		}

-		case 60: {

+		case 61: {

 			WhileStmt(out s);

 			break;

 		}

-		case 62: {

+		case 63: {

 			MatchStmt(out s);

 			break;

 		}

-		case 66: {

+		case 67: {

 			ParallelStmt(out s);

 			break;

 		}

@@ -1091,8 +1091,8 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 					Get();

 					breakCount++; 

 				}

-			} else SynErr(138);

-			while (!(la.kind == 0 || la.kind == 18)) {SynErr(139); Get();}

+			} else SynErr(139);

+			while (!(la.kind == 0 || la.kind == 18)) {SynErr(140); Get();}

 			Expect(18);

 			s = label != null ? new BreakStmt(x, label) : new BreakStmt(x, breakCount); 

 			break;

@@ -1107,7 +1107,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			Expect(18);

 			break;

 		}

-		default: SynErr(140); break;

+		default: SynErr(141); break;

 		}

 	}

 

@@ -1115,7 +1115,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		Contract.Ensures(Contract.ValueAtReturn(out s) != null); IToken/*!*/ x;

 		Expression/*!*/ e = null; Attributes attrs = null;

 		

-		Expect(63);

+		Expect(64);

 		x = t; s = null;

 		while (IsAttribute()) {

 			Attribute(ref attrs);

@@ -1124,7 +1124,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			Expression(out e);

 		} else if (la.kind == 27) {

 			Get();

-		} else SynErr(141);

+		} else SynErr(142);

 		Expect(18);

 		if (e == null) {

 		 s = new SkeletonStatement(new AssertStmt(x, new LiteralExpr(x, true), attrs), true, false);

@@ -1136,7 +1136,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 

 	void AssumeStmt(out Statement/*!*/ s) {

 		Contract.Ensures(Contract.ValueAtReturn(out s) != null); IToken/*!*/ x;  Expression/*!*/ e; 

-		Expect(64);

+		Expect(65);

 		x = t; 

 		Expression(out e);

 		Expect(18);

@@ -1147,7 +1147,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		Contract.Ensures(Contract.ValueAtReturn(out s) != null); IToken/*!*/ x;  Attributes.Argument/*!*/ arg;

 		List<Attributes.Argument/*!*/> args = new List<Attributes.Argument/*!*/>();

 		

-		Expect(65);

+		Expect(66);

 		x = t; 

 		AttributeArg(out arg);

 		args.Add(arg); 

@@ -1167,6 +1167,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		Expression lhs0;

 		IToken x;

 		Attributes attrs = null;

+		Expression suchThat = null;

 		

 		Lhs(out e);

 		x = e.tok; 

@@ -1176,28 +1177,39 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			}

 			Expect(18);

 			rhss.Add(new ExprRhs(e, attrs)); 

-		} else if (la.kind == 20 || la.kind == 50) {

+		} else if (la.kind == 20 || la.kind == 50 || la.kind == 51) {

 			lhss.Add(e);  lhs0 = e; 

 			while (la.kind == 20) {

 				Get();

 				Lhs(out e);

 				lhss.Add(e); 

 			}

-			Expect(50);

-			x = t; 

-			Rhs(out r, lhs0);

-			rhss.Add(r); 

-			while (la.kind == 20) {

+			if (la.kind == 50) {

 				Get();

+				x = t; 

 				Rhs(out r, lhs0);

 				rhss.Add(r); 

-			}

+				while (la.kind == 20) {

+					Get();

+					Rhs(out r, lhs0);

+					rhss.Add(r); 

+				}

+			} else if (la.kind == 51) {

+				Get();

+				x = t; 

+				Expression(out suchThat);

+			} else SynErr(143);

 			Expect(18);

 		} else if (la.kind == 5) {

 			Get();

 			SemErr(t, "invalid statement (did you forget the 'label' keyword?)"); 

-		} else SynErr(142);

-		s = new UpdateStmt(x, lhss, rhss); 

+		} else SynErr(144);

+		if (suchThat != null) {

+		 s = new AssignSuchThatStmt(x, lhss, suchThat);

+		} else {

+		 s = new UpdateStmt(x, lhss, rhss);

+		}

+		

 	}

 

 	void VarDeclStatement(out Statement/*!*/ s) {

@@ -1206,6 +1218,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		AssignmentRhs r;  IdentifierExpr lhs0;

 		List<VarDecl> lhss = new List<VarDecl>();

 		List<AssignmentRhs> rhss = new List<AssignmentRhs>();

+		Expression suchThat = null;

 		

 		if (la.kind == 8) {

 			Get();

@@ -1220,23 +1233,35 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			LocalIdentTypeOptional(out d, isGhost);

 			lhss.Add(d); 

 		}

-		if (la.kind == 50) {

-			Get();

-			assignTok = t;

-			lhs0 = new IdentifierExpr(lhss[0].Tok, lhss[0].Name);

-			lhs0.Var = lhss[0];  lhs0.Type = lhss[0].OptionalType;  // resolve here

-			

-			Rhs(out r, lhs0);

-			rhss.Add(r); 

-			while (la.kind == 20) {

+		if (la.kind == 50 || la.kind == 51) {

+			if (la.kind == 50) {

 				Get();

+				assignTok = t;

+				lhs0 = new IdentifierExpr(lhss[0].Tok, lhss[0].Name);

+				lhs0.Var = lhss[0];  lhs0.Type = lhss[0].OptionalType;  // resolve here

+				

 				Rhs(out r, lhs0);

 				rhss.Add(r); 

+				while (la.kind == 20) {

+					Get();

+					Rhs(out r, lhs0);

+					rhss.Add(r); 

+				}

+			} else {

+				Get();

+				assignTok = t; 

+				Expression(out suchThat);

 			}

 		}

 		Expect(18);

-		UpdateStmt update;

-		if (rhss.Count == 0) {

+		ConcreteUpdateStatement update;

+		if (suchThat != null) {

+		 var ies = new List<Expression>();

+		 foreach (var lhs in lhss) {

+		   ies.Add(new IdentifierExpr(lhs.Tok, lhs.Name));

+		 }

+		 update = new AssignSuchThatStmt(assignTok, ies, suchThat);

+		} else if (rhss.Count == 0) {

 		 update = null;

 		} else {

 		 var ies = new List<Expression>();

@@ -1260,7 +1285,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		List<GuardedAlternative> alternatives;

 		ifStmt = dummyStmt;  // to please the compiler

 		

-		Expect(56);

+		Expect(57);

 		x = t; 

 		if (la.kind == 27 || la.kind == 33) {

 			if (la.kind == 33) {

@@ -1270,15 +1295,15 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 				guardOmitted = true; 

 			}

 			BlockStmt(out thn, out bodyStart, out bodyEnd);

-			if (la.kind == 57) {

+			if (la.kind == 58) {

 				Get();

-				if (la.kind == 56) {

+				if (la.kind == 57) {

 					IfStmt(out s);

 					els = s; 

 				} else if (la.kind == 6) {

 					BlockStmt(out bs, out bodyStart, out bodyEnd);

 					els = bs; 

-				} else SynErr(143);

+				} else SynErr(145);

 			}

 			if (guardOmitted) {

 			 ifStmt = new SkeletonStatement(new IfStmt(x, guard, thn, els), true, false);

@@ -1289,7 +1314,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		} else if (la.kind == 6) {

 			AlternativeBlock(out alternatives);

 			ifStmt = new AlternativeStmt(x, alternatives); 

-		} else SynErr(144);

+		} else SynErr(146);

 	}

 

 	void WhileStmt(out Statement/*!*/ stmt) {

@@ -1305,7 +1330,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		List<GuardedAlternative> alternatives;

 		stmt = dummyStmt;  // to please the compiler

 		

-		Expect(60);

+		Expect(61);

 		x = t; 

 		if (la.kind == 27 || la.kind == 33) {

 			if (la.kind == 33) {

@@ -1321,7 +1346,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			} else if (la.kind == 27) {

 				Get();

 				bodyOmitted = true; 

-			} else SynErr(145);

+			} else SynErr(147);

 			if (guardOmitted || bodyOmitted) {

 			 if (decreases.Count != 0) {

 			   SemErr(decreases[0].tok, "'decreases' clauses are not allowed on refining loops");

@@ -1342,18 +1367,18 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			LoopSpec(out invariants, out decreases, out mod, ref decAttrs, ref modAttrs);

 			AlternativeBlock(out alternatives);

 			stmt = new AlternativeLoopStmt(x, invariants, new Specification<Expression>(decreases, decAttrs), new Specification<FrameExpression>(mod, modAttrs), alternatives); 

-		} else SynErr(146);

+		} else SynErr(148);

 	}

 

 	void MatchStmt(out Statement/*!*/ s) {

 		Contract.Ensures(Contract.ValueAtReturn(out s) != null);

 		Token x;  Expression/*!*/ e;  MatchCaseStmt/*!*/ c;

 		List<MatchCaseStmt/*!*/> cases = new List<MatchCaseStmt/*!*/>(); 

-		Expect(62);

+		Expect(63);

 		x = t; 

 		Expression(out e);

 		Expect(6);

-		while (la.kind == 58) {

+		while (la.kind == 59) {

 			CaseStatement(out c);

 			cases.Add(c); 

 		}

@@ -1373,7 +1398,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		BlockStmt/*!*/ block;

 		IToken bodyStart, bodyEnd;

 		

-		Expect(66);

+		Expect(67);

 		x = t; 

 		Expect(33);

 		if (la.kind == 1) {

@@ -1430,16 +1455,16 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		r = null;  // to please compiler

 		Attributes attrs = null;

 		

-		if (la.kind == 51) {

+		if (la.kind == 52) {

 			Get();

 			newToken = t; 

 			TypeAndToken(out x, out ty);

-			if (la.kind == 52 || la.kind == 54) {

-				if (la.kind == 52) {

+			if (la.kind == 53 || la.kind == 55) {

+				if (la.kind == 53) {

 					Get();

 					ee = new List<Expression>(); 

 					Expressions(ee);

-					Expect(53);

+					Expect(54);

 					UserDefinedType tmp = theBuiltIns.ArrayType(x, ee.Count, new IntType(), true);

 					

 				} else {

@@ -1461,7 +1486,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			 r = new TypeRhs(newToken, ty, initCall);

 			}

 			

-		} else if (la.kind == 55) {

+		} else if (la.kind == 56) {

 			Get();

 			x = t; 

 			Expression(out e);

@@ -1472,7 +1497,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		} else if (StartOf(9)) {

 			Expression(out e);

 			r = new ExprRhs(e); 

-		} else SynErr(147);

+		} else SynErr(149);

 		while (la.kind == 6) {

 			Attribute(ref attrs);

 		}

@@ -1484,16 +1509,16 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		

 		if (la.kind == 1) {

 			DottedIdentifiersAndFunction(out e);

-			while (la.kind == 52 || la.kind == 54) {

+			while (la.kind == 53 || la.kind == 55) {

 				Suffix(ref e);

 			}

 		} else if (StartOf(15)) {

 			ConstAtomExpression(out e);

 			Suffix(ref e);

-			while (la.kind == 52 || la.kind == 54) {

+			while (la.kind == 53 || la.kind == 55) {

 				Suffix(ref e);

 			}

-		} else SynErr(148);

+		} else SynErr(150);

 	}

 

 	void Expressions(List<Expression/*!*/>/*!*/ args) {

@@ -1516,7 +1541,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		} else if (StartOf(9)) {

 			Expression(out ee);

 			e = ee; 

-		} else SynErr(149);

+		} else SynErr(151);

 		Expect(34);

 	}

 

@@ -1527,11 +1552,11 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		List<Statement> body;

 		

 		Expect(6);

-		while (la.kind == 58) {

+		while (la.kind == 59) {

 			Get();

 			x = t; 

 			Expression(out e);

-			Expect(59);

+			Expect(60);

 			body = new List<Statement>(); 

 			while (StartOf(10)) {

 				Stmt(body);

@@ -1549,22 +1574,22 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		mod = null;

 		

 		while (StartOf(16)) {

-			if (la.kind == 29 || la.kind == 61) {

+			if (la.kind == 29 || la.kind == 62) {

 				Invariant(out invariant);

-				while (!(la.kind == 0 || la.kind == 18)) {SynErr(150); Get();}

+				while (!(la.kind == 0 || la.kind == 18)) {SynErr(152); Get();}

 				Expect(18);

 				invariants.Add(invariant); 

 			} else if (la.kind == 32) {

-				while (!(la.kind == 0 || la.kind == 32)) {SynErr(151); Get();}

+				while (!(la.kind == 0 || la.kind == 32)) {SynErr(153); Get();}

 				Get();

 				while (IsAttribute()) {

 					Attribute(ref decAttrs);

 				}

 				DecreasesList(decreases, true);

-				while (!(la.kind == 0 || la.kind == 18)) {SynErr(152); Get();}

+				while (!(la.kind == 0 || la.kind == 18)) {SynErr(154); Get();}

 				Expect(18);

 			} else {

-				while (!(la.kind == 0 || la.kind == 28)) {SynErr(153); Get();}

+				while (!(la.kind == 0 || la.kind == 28)) {SynErr(155); Get();}

 				Get();

 				while (IsAttribute()) {

 					Attribute(ref modAttrs);

@@ -1579,7 +1604,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 						mod.Add(fe); 

 					}

 				}

-				while (!(la.kind == 0 || la.kind == 18)) {SynErr(154); Get();}

+				while (!(la.kind == 0 || la.kind == 18)) {SynErr(156); Get();}

 				Expect(18);

 			}

 		}

@@ -1587,12 +1612,12 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 

 	void Invariant(out MaybeFreeExpression/*!*/ invariant) {

 		bool isFree = false; Expression/*!*/ e; List<string> ids = new List<string>(); invariant = null; Attributes attrs = null; 

-		while (!(la.kind == 0 || la.kind == 29 || la.kind == 61)) {SynErr(155); Get();}

+		while (!(la.kind == 0 || la.kind == 29 || la.kind == 62)) {SynErr(157); Get();}

 		if (la.kind == 29) {

 			Get();

 			isFree = true; 

 		}

-		Expect(61);

+		Expect(62);

 		while (IsAttribute()) {

 			Attribute(ref attrs);

 		}

@@ -1607,7 +1632,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		BoundVar/*!*/ bv;

 		List<Statement/*!*/> body = new List<Statement/*!*/>();

 		

-		Expect(58);

+		Expect(59);

 		x = t; 

 		Ident(out id);

 		if (la.kind == 33) {

@@ -1621,7 +1646,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			}

 			Expect(34);

 		}

-		Expect(59);

+		Expect(60);

 		while (StartOf(10)) {

 			Stmt(body);

 		}

@@ -1636,7 +1661,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		} else if (StartOf(9)) {

 			Expression(out e);

 			arg = new Attributes.Argument(t, e); 

-		} else SynErr(156);

+		} else SynErr(158);

 	}

 

 	void QuantifierDomain(out List<BoundVar/*!*/> bvars, out Attributes attrs, out Expression range) {

@@ -1664,7 +1689,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 	void EquivExpression(out Expression/*!*/ e0) {

 		Contract.Ensures(Contract.ValueAtReturn(out e0) != null); IToken/*!*/ x;  Expression/*!*/ e1; 

 		ImpliesExpression(out e0);

-		while (la.kind == 67 || la.kind == 68) {

+		while (la.kind == 68 || la.kind == 69) {

 			EquivOp();

 			x = t; 

 			ImpliesExpression(out e1);

@@ -1675,7 +1700,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 	void ImpliesExpression(out Expression/*!*/ e0) {

 		Contract.Ensures(Contract.ValueAtReturn(out e0) != null); IToken/*!*/ x;  Expression/*!*/ e1; 

 		LogicalExpression(out e0);

-		if (la.kind == 69 || la.kind == 70) {

+		if (la.kind == 70 || la.kind == 71) {

 			ImpliesOp();

 			x = t; 

 			ImpliesExpression(out e1);

@@ -1684,23 +1709,23 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 	}

 

 	void EquivOp() {

-		if (la.kind == 67) {

+		if (la.kind == 68) {

 			Get();

-		} else if (la.kind == 68) {

+		} else if (la.kind == 69) {

 			Get();

-		} else SynErr(157);

+		} else SynErr(159);

 	}

 

 	void LogicalExpression(out Expression/*!*/ e0) {

 		Contract.Ensures(Contract.ValueAtReturn(out e0) != null); IToken/*!*/ x;  Expression/*!*/ e1; 

 		RelationalExpression(out e0);

 		if (StartOf(17)) {

-			if (la.kind == 71 || la.kind == 72) {

+			if (la.kind == 72 || la.kind == 73) {

 				AndOp();

 				x = t; 

 				RelationalExpression(out e1);

 				e0 = new BinaryExpr(x, BinaryExpr.Opcode.And, e0, e1); 

-				while (la.kind == 71 || la.kind == 72) {

+				while (la.kind == 72 || la.kind == 73) {

 					AndOp();

 					x = t; 

 					RelationalExpression(out e1);

@@ -1711,7 +1736,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 				x = t; 

 				RelationalExpression(out e1);

 				e0 = new BinaryExpr(x, BinaryExpr.Opcode.Or, e0, e1); 

-				while (la.kind == 73 || la.kind == 74) {

+				while (la.kind == 74 || la.kind == 75) {

 					OrOp();

 					x = t; 

 					RelationalExpression(out e1);

@@ -1722,11 +1747,11 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 	}

 

 	void ImpliesOp() {

-		if (la.kind == 69) {

+		if (la.kind == 70) {

 			Get();

-		} else if (la.kind == 70) {

+		} else if (la.kind == 71) {

 			Get();

-		} else SynErr(158);

+		} else SynErr(160);

 	}

 

 	void RelationalExpression(out Expression/*!*/ e) {

@@ -1820,25 +1845,25 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 	}

 

 	void AndOp() {

-		if (la.kind == 71) {

+		if (la.kind == 72) {

 			Get();

-		} else if (la.kind == 72) {

+		} else if (la.kind == 73) {

 			Get();

-		} else SynErr(159);

+		} else SynErr(161);

 	}

 

 	void OrOp() {

-		if (la.kind == 73) {

+		if (la.kind == 74) {

 			Get();

-		} else if (la.kind == 74) {

+		} else if (la.kind == 75) {

 			Get();

-		} else SynErr(160);

+		} else SynErr(162);

 	}

 

 	void Term(out Expression/*!*/ e0) {

 		Contract.Ensures(Contract.ValueAtReturn(out e0) != null); IToken/*!*/ x;  Expression/*!*/ e1;  BinaryExpr.Opcode op; 

 		Factor(out e0);

-		while (la.kind == 85 || la.kind == 86) {

+		while (la.kind == 86 || la.kind == 87) {

 			AddOp(out x, out op);

 			Factor(out e1);

 			e0 = new BinaryExpr(x, op, e0, e1); 

@@ -1851,7 +1876,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		IToken y;

 		

 		switch (la.kind) {

-		case 75: {

+		case 76: {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Eq; 

 			break;

@@ -1866,35 +1891,35 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			x = t;  op = BinaryExpr.Opcode.Gt; 

 			break;

 		}

-		case 76: {

+		case 77: {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Le; 

 			break;

 		}

-		case 77: {

+		case 78: {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Ge; 

 			break;

 		}

-		case 78: {

+		case 79: {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Neq; 

 			break;

 		}

-		case 79: {

+		case 80: {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Disjoint; 

 			break;

 		}

-		case 80: {

+		case 81: {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.In; 

 			break;

 		}

-		case 81: {

+		case 82: {

 			Get();

 			x = t;  y = Token.NoToken; 

-			if (la.kind == 80) {

+			if (la.kind == 81) {

 				Get();

 				y = t; 

 			}

@@ -1909,29 +1934,29 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			

 			break;

 		}

-		case 82: {

+		case 83: {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Neq; 

 			break;

 		}

-		case 83: {

+		case 84: {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Le; 

 			break;

 		}

-		case 84: {

+		case 85: {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Ge; 

 			break;

 		}

-		default: SynErr(161); break;

+		default: SynErr(163); break;

 		}

 	}

 

 	void Factor(out Expression/*!*/ e0) {

 		Contract.Ensures(Contract.ValueAtReturn(out e0) != null); IToken/*!*/ x;  Expression/*!*/ e1;  BinaryExpr.Opcode op; 

 		UnaryExpression(out e0);

-		while (la.kind == 45 || la.kind == 87 || la.kind == 88) {

+		while (la.kind == 45 || la.kind == 88 || la.kind == 89) {

 			MulOp(out x, out op);

 			UnaryExpression(out e1);

 			e0 = new BinaryExpr(x, op, e0, e1); 

@@ -1940,44 +1965,44 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 

 	void AddOp(out IToken/*!*/ x, out BinaryExpr.Opcode op) {

 		Contract.Ensures(Contract.ValueAtReturn(out x) != null); x = Token.NoToken;  op=BinaryExpr.Opcode.Add/*(dummy)*/; 

-		if (la.kind == 85) {

+		if (la.kind == 86) {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Add; 

-		} else if (la.kind == 86) {

+		} else if (la.kind == 87) {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Sub; 

-		} else SynErr(162);

+		} else SynErr(164);

 	}

 

 	void UnaryExpression(out Expression/*!*/ e) {

 		Contract.Ensures(Contract.ValueAtReturn(out e) != null); IToken/*!*/ x;  e = dummyExpr; 

 		switch (la.kind) {

-		case 86: {

+		case 87: {

 			Get();

 			x = t; 

 			UnaryExpression(out e);

 			e = new BinaryExpr(x, BinaryExpr.Opcode.Sub, new LiteralExpr(x, 0), e); 

 			break;

 		}

-		case 81: case 89: {

+		case 82: case 90: {

 			NegOp();

 			x = t; 

 			UnaryExpression(out e);

 			e = new UnaryExpr(x, UnaryExpr.Opcode.Not, e); 

 			break;

 		}

-		case 19: case 38: case 56: case 62: case 63: case 64: case 99: case 100: case 101: case 102: {

+		case 19: case 38: case 57: case 63: case 64: case 65: case 100: case 101: case 102: case 103: {

 			EndlessExpression(out e);

 			break;

 		}

 		case 1: {

 			DottedIdentifiersAndFunction(out e);

-			while (la.kind == 52 || la.kind == 54) {

+			while (la.kind == 53 || la.kind == 55) {

 				Suffix(ref e);

 			}

 			break;

 		}

-		case 6: case 52: {

+		case 6: case 53: {

 			DisplayExpr(out e);

 			break;

 		}

@@ -1985,14 +2010,14 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			MultiSetExpr(out e);

 			break;

 		}

-		case 2: case 17: case 33: case 90: case 91: case 92: case 93: case 94: case 95: case 96: {

+		case 2: case 17: case 33: case 91: case 92: case 93: case 94: case 95: case 96: case 97: {

 			ConstAtomExpression(out e);

-			while (la.kind == 52 || la.kind == 54) {

+			while (la.kind == 53 || la.kind == 55) {

 				Suffix(ref e);

 			}

 			break;

 		}

-		default: SynErr(163); break;

+		default: SynErr(165); break;

 		}

 	}

 

@@ -2001,21 +2026,21 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		if (la.kind == 45) {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Mul; 

-		} else if (la.kind == 87) {

+		} else if (la.kind == 88) {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Div; 

-		} else if (la.kind == 88) {

+		} else if (la.kind == 89) {

 			Get();

 			x = t;  op = BinaryExpr.Opcode.Mod; 

-		} else SynErr(164);

+		} else SynErr(166);

 	}

 

 	void NegOp() {

-		if (la.kind == 81) {

+		if (la.kind == 82) {

 			Get();

-		} else if (la.kind == 89) {

+		} else if (la.kind == 90) {

 			Get();

-		} else SynErr(165);

+		} else SynErr(167);

 	}

 

 	void EndlessExpression(out Expression e) {

@@ -2026,22 +2051,22 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		List<BoundVar> letVars;  List<Expression> letRHSs;

 		

 		switch (la.kind) {

-		case 56: {

+		case 57: {

 			Get();

 			x = t; 

 			Expression(out e);

-			Expect(97);

+			Expect(98);

 			Expression(out e0);

-			Expect(57);

+			Expect(58);

 			Expression(out e1);

 			e = new ITEExpr(x, e, e0, e1); 

 			break;

 		}

-		case 62: {

+		case 63: {

 			MatchExpression(out e);

 			break;

 		}

-		case 99: case 100: case 101: case 102: {

+		case 100: case 101: case 102: case 103: {

 			QuantifierGuts(out e);

 			break;

 		}

@@ -2049,7 +2074,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			ComprehensionExpr(out e);

 			break;

 		}

-		case 63: {

+		case 64: {

 			Get();

 			x = t; 

 			Expression(out e0);

@@ -2058,7 +2083,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			e = new AssertExpr(x, e0, e1); 

 			break;

 		}

-		case 64: {

+		case 65: {

 			Get();

 			x = t; 

 			Expression(out e0);

@@ -2092,7 +2117,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			e = new LetExpr(x, letVars, letRHSs, e); 

 			break;

 		}

-		default: SynErr(166); break;

+		default: SynErr(168); break;

 		}

 	}

 

@@ -2103,7 +2128,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		

 		Ident(out id);

 		idents.Add(id); 

-		while (la.kind == 54) {

+		while (la.kind == 55) {

 			Get();

 			Ident(out id);

 			idents.Add(id); 

@@ -2125,7 +2150,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		List<Expression> multipleIndices = null;

 		bool func = false;

 		

-		if (la.kind == 54) {

+		if (la.kind == 55) {

 			Get();

 			Ident(out id);

 			if (la.kind == 33) {

@@ -2138,13 +2163,13 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 				e = new FunctionCallExpr(id, id.val, e, openParen, args); 

 			}

 			if (!func) { e = new ExprDotName(id, e, id.val); } 

-		} else if (la.kind == 52) {

+		} else if (la.kind == 53) {

 			Get();

 			x = t; 

 			if (StartOf(9)) {

 				Expression(out ee);

 				e0 = ee; 

-				if (la.kind == 98) {

+				if (la.kind == 99) {

 					Get();

 					anyDots = true; 

 					if (StartOf(9)) {

@@ -2155,7 +2180,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 					Get();

 					Expression(out ee);

 					e1 = ee; 

-				} else if (la.kind == 20 || la.kind == 53) {

+				} else if (la.kind == 20 || la.kind == 54) {

 					while (la.kind == 20) {

 						Get();

 						Expression(out ee);

@@ -2166,15 +2191,15 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 						multipleIndices.Add(ee);

 						

 					}

-				} else SynErr(167);

-			} else if (la.kind == 98) {

+				} else SynErr(169);

+			} else if (la.kind == 99) {

 				Get();

 				anyDots = true; 

 				if (StartOf(9)) {

 					Expression(out ee);

 					e1 = ee; 

 				}

-			} else SynErr(168);

+			} else SynErr(170);

 			if (multipleIndices != null) {

 			 e = new MultiSelectExpr(x, e, multipleIndices);

 			 // make sure an array class with this dimensionality exists

@@ -2197,8 +2222,8 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			 }

 			}

 			

-			Expect(53);

-		} else SynErr(169);

+			Expect(54);

+		} else SynErr(171);

 	}

 

 	void DisplayExpr(out Expression e) {

@@ -2214,15 +2239,15 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			}

 			e = new SetDisplayExpr(x, elements);

 			Expect(7);

-		} else if (la.kind == 52) {

+		} else if (la.kind == 53) {

 			Get();

 			x = t;  elements = new List<Expression/*!*/>(); 

 			if (StartOf(9)) {

 				Expressions(elements);

 			}

 			e = new SeqDisplayExpr(x, elements); 

-			Expect(53);

-		} else SynErr(170);

+			Expect(54);

+		} else SynErr(172);

 	}

 

 	void MultiSetExpr(out Expression e) {

@@ -2248,7 +2273,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			Expect(34);

 		} else if (StartOf(19)) {

 			SemErr("multiset must be followed by multiset literal or expression to coerce in parentheses."); 

-		} else SynErr(171);

+		} else SynErr(173);

 	}

 

 	void ConstAtomExpression(out Expression/*!*/ e) {

@@ -2257,17 +2282,17 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		e = dummyExpr;

 		

 		switch (la.kind) {

-		case 90: {

+		case 91: {

 			Get();

 			e = new LiteralExpr(t, false); 

 			break;

 		}

-		case 91: {

+		case 92: {

 			Get();

 			e = new LiteralExpr(t, true); 

 			break;

 		}

-		case 92: {

+		case 93: {

 			Get();

 			e = new LiteralExpr(t); 

 			break;

@@ -2277,12 +2302,12 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			e = new LiteralExpr(t, n); 

 			break;

 		}

-		case 93: {

+		case 94: {

 			Get();

 			e = new ThisExpr(t); 

 			break;

 		}

-		case 94: {

+		case 95: {

 			Get();

 			x = t; 

 			Expect(33);

@@ -2291,7 +2316,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			e = new FreshExpr(x, e); 

 			break;

 		}

-		case 95: {

+		case 96: {

 			Get();

 			x = t; 

 			Expect(33);

@@ -2300,7 +2325,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			e = new AllocatedExpr(x, e); 

 			break;

 		}

-		case 96: {

+		case 97: {

 			Get();

 			x = t; 

 			Expect(33);

@@ -2325,7 +2350,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			Expect(34);

 			break;

 		}

-		default: SynErr(172); break;

+		default: SynErr(174); break;

 		}

 	}

 

@@ -2344,10 +2369,10 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		Contract.Ensures(Contract.ValueAtReturn(out e) != null); IToken/*!*/ x;  MatchCaseExpr/*!*/ c;

 		List<MatchCaseExpr/*!*/> cases = new List<MatchCaseExpr/*!*/>();

 		

-		Expect(62);

+		Expect(63);

 		x = t; 

 		Expression(out e);

-		while (la.kind == 58) {

+		while (la.kind == 59) {

 			CaseExpression(out c);

 			cases.Add(c); 

 		}

@@ -2362,13 +2387,13 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		Expression range;

 		Expression/*!*/ body;

 		

-		if (la.kind == 99 || la.kind == 100) {

+		if (la.kind == 100 || la.kind == 101) {

 			Forall();

 			x = t;  univ = true; 

-		} else if (la.kind == 101 || la.kind == 102) {

+		} else if (la.kind == 102 || la.kind == 103) {

 			Exists();

 			x = t; 

-		} else SynErr(173);

+		} else SynErr(175);

 		QuantifierDomain(out bvars, out attrs, out range);

 		QSep();

 		Expression(out body);

@@ -2399,7 +2424,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		}

 		Expect(17);

 		Expression(out range);

-		if (la.kind == 103 || la.kind == 104) {

+		if (la.kind == 104 || la.kind == 105) {

 			QSep();

 			Expression(out body);

 		}

@@ -2414,7 +2439,7 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 		BoundVar/*!*/ bv;

 		Expression/*!*/ body;

 		

-		Expect(58);

+		Expect(59);

 		x = t; 

 		Ident(out id);

 		if (la.kind == 33) {

@@ -2428,33 +2453,33 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 			}

 			Expect(34);

 		}

-		Expect(59);

+		Expect(60);

 		Expression(out body);

 		c = new MatchCaseExpr(x, id.val, arguments, body); 

 	}

 

 	void Forall() {

-		if (la.kind == 99) {

+		if (la.kind == 100) {

 			Get();

-		} else if (la.kind == 100) {

+		} else if (la.kind == 101) {

 			Get();

-		} else SynErr(174);

+		} else SynErr(176);

 	}

 

 	void Exists() {

-		if (la.kind == 101) {

+		if (la.kind == 102) {

 			Get();

-		} else if (la.kind == 102) {

+		} else if (la.kind == 103) {

 			Get();

-		} else SynErr(175);

+		} else SynErr(177);

 	}

 

 	void QSep() {

-		if (la.kind == 103) {

+		if (la.kind == 104) {

 			Get();

-		} else if (la.kind == 104) {

+		} else if (la.kind == 105) {

 			Get();

-		} else SynErr(176);

+		} else SynErr(178);

 	}

 

 	void AttributeBody(ref Attributes attrs) {

@@ -2490,27 +2515,27 @@ List<Expression/*!*/>/*!*/ decreases, ref Attributes decAttrs, ref Attributes mo
 	}

 

 	static readonly bool[,]/*!*/ set = {

-		{T,T,T,x, x,x,T,x, T,x,x,x, T,x,x,T, x,T,T,T, x,x,x,x, T,T,x,T, T,T,T,T, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,x,x, x,x,x,x, T,x,x,x, T,T,T,T, T,T,T,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, T,T,T,T, T,x,x,x, x,x,x,x, x,x,x},

-		{x,x,x,x, x,x,x,x, T,T,x,x, T,T,T,T, x,x,x,T, x,T,x,x, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{x,x,x,x, x,x,x,x, T,x,x,x, T,T,T,T, x,x,x,T, x,T,x,x, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{x,x,x,x, x,x,x,x, T,x,x,x, x,T,T,x, x,x,x,T, x,x,x,x, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{T,x,x,x, x,x,T,T, T,T,x,x, T,T,T,T, x,x,x,T, x,T,T,x, T,T,x,x, x,x,T,T, T,T,x,x, x,x,x,x, x,x,T,T, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, T,x,x,x, x,x,x,x, x,x,x,x, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,T,T, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{x,T,x,T, x,x,x,x, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,T,T, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,T,T, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{x,T,T,x, x,x,T,x, x,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, T,x,x,x, T,x,x,x, x,x,T,T, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,x, x,T,T,T, T,T,T,T, T,x,x,T, T,T,T,x, x,x,x},

-		{x,T,T,x, x,x,T,x, T,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,T, x,x,x,x, x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,x,x, x,x,x,x, T,x,x,x, T,x,T,T, T,T,T,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, T,T,T,T, T,x,x,x, x,x,x,x, x,x,x},

-		{x,T,T,x, x,x,T,x, x,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,T, x,x,x,x, x,T,x,x, x,x,x,x, T,x,x,x, T,x,x,x, x,x,T,T, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,x, x,T,T,T, T,T,T,T, T,x,x,T, T,T,T,x, x,x,x},

-		{T,T,T,x, x,x,T,x, T,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,T, x,x,x,x, x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,x,x, x,x,x,x, T,x,x,x, T,x,T,T, T,T,T,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, T,T,T,T, T,x,x,x, x,x,x,x, x,x,x},

-		{x,x,x,x, x,x,T,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,x,x, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{x,T,T,x, x,x,T,x, x,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,T, x,x,x,x, x,T,x,x, x,x,x,T, T,x,x,T, T,x,x,x, x,x,T,T, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,x, x,T,T,T, T,T,T,T, T,x,x,T, T,T,T,x, x,x,x},

-		{x,x,T,x, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, T,T,T,T, T,x,x,x, x,x,x,x, x,x,x},

-		{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,x,x, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,T,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,T,T, T,T,T,T, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x},

-		{x,x,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,T,T,x, T,x,T,T, x,x,x,x, x,x,x,x, x,x,T,x, x,x,x,x, x,x,x,x, x,T,T,x, x,x,T,x, x,T,x,x, x,T,T,T, x,x,x,x, x,x,x,T, T,T,T,T, T,T,T,T, T,T,T,T, T,T,T,T, T,T,T,T, T,x,x,x, x,x,x,x, x,T,T,x, x,x,x,T, T,x,x},

-		{x,T,T,x, T,x,T,x, x,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, T,x,x,x, T,x,x,x, x,x,T,T, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,x, x,T,T,T, T,T,T,T, T,x,x,T, T,T,T,x, x,x,x}

+		{T,T,T,x, x,x,T,x, T,x,x,x, T,x,x,T, x,T,T,T, x,x,x,x, T,T,x,T, T,T,T,T, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,x,x, x,x,x,x, x,T,x,x, x,T,T,T, T,T,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,T,T, T,T,x,x, x,x,x,x, x,x,x,x},

+		{x,x,x,x, x,x,x,x, T,T,x,x, T,T,T,T, x,x,x,T, x,T,x,x, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{x,x,x,x, x,x,x,x, T,x,x,x, T,T,T,T, x,x,x,T, x,T,x,x, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{x,x,x,x, x,x,x,x, T,x,x,x, x,T,T,x, x,x,x,T, x,x,x,x, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{T,x,x,x, x,x,T,T, T,T,x,x, T,T,T,T, x,x,x,T, x,T,T,x, T,T,x,x, x,x,T,T, T,T,x,x, x,x,x,x, x,x,T,T, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, T,x,x,x, x,x,x,x, x,x,x,x, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,T,T, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{x,T,x,T, x,x,x,x, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,T,T, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,T,T, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{x,T,T,x, x,x,T,x, x,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,T,x,x, x,x,x,T, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,x, x,x,x,T, x,x,T,T, T,T,T,T, T,T,x,x, T,T,T,T, x,x,x,x},

+		{x,T,T,x, x,x,T,x, T,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,T, x,x,x,x, x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,x,x, x,x,x,x, x,T,x,x, x,T,x,T, T,T,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,T,T, T,T,x,x, x,x,x,x, x,x,x,x},

+		{x,T,T,x, x,x,T,x, x,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,T, x,x,x,x, x,T,x,x, x,x,x,x, x,T,x,x, x,T,x,x, x,x,x,T, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,x, x,x,x,T, x,x,T,T, T,T,T,T, T,T,x,x, T,T,T,T, x,x,x,x},

+		{T,T,T,x, x,x,T,x, T,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,T, x,x,x,x, x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,x,x, x,x,x,x, x,T,x,x, x,T,x,T, T,T,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,T,T, T,T,x,x, x,x,x,x, x,x,x,x},

+		{x,x,x,x, x,x,T,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,x,x, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{x,T,T,x, x,x,T,x, x,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,T, x,x,x,x, x,T,x,x, x,x,x,x, T,T,x,x, T,T,x,x, x,x,x,T, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,x, x,x,x,T, x,x,T,T, T,T,T,T, T,T,x,x, T,T,T,T, x,x,x,x},

+		{x,x,T,x, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,T, T,T,T,T, T,T,x,x, x,x,x,x, x,x,x,x},

+		{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,x,x, T,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, T,T,T,T, T,T,T,T, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x},

+		{x,x,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,T,T,x, T,x,T,T, x,x,x,x, x,x,x,x, x,x,T,x, x,x,x,x, x,x,x,x, x,T,T,x, x,x,T,x, x,x,T,x, x,x,T,T, T,x,x,x, x,x,x,x, T,T,T,T, T,T,T,T, T,T,T,T, T,T,T,T, T,T,T,T, T,T,x,x, x,x,x,x, x,x,T,T, x,x,x,x, T,T,x,x},

+		{x,T,T,x, T,x,T,x, x,x,x,x, x,x,x,x, x,T,x,T, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,x,T,T, x,x,x,x, x,x,x,x, x,x,x,x, x,T,x,x, x,T,x,x, x,x,x,T, T,T,x,x, x,x,x,x, x,x,x,x, x,x,x,x, x,x,T,x, x,x,x,T, x,x,T,T, T,T,T,T, T,T,x,x, T,T,T,T, x,x,x,x}

 

 	};

 } // end Parser

@@ -2586,132 +2611,134 @@ public class Errors {
 			case 48: s = "\"break\" expected"; break;

 			case 49: s = "\"return\" expected"; break;

 			case 50: s = "\":=\" expected"; break;

-			case 51: s = "\"new\" expected"; break;

-			case 52: s = "\"[\" expected"; break;

-			case 53: s = "\"]\" expected"; break;

-			case 54: s = "\".\" expected"; break;

-			case 55: s = "\"choose\" expected"; break;

-			case 56: s = "\"if\" expected"; break;

-			case 57: s = "\"else\" expected"; break;

-			case 58: s = "\"case\" expected"; break;

-			case 59: s = "\"=>\" expected"; break;

-			case 60: s = "\"while\" expected"; break;

-			case 61: s = "\"invariant\" expected"; break;

-			case 62: s = "\"match\" expected"; break;

-			case 63: s = "\"assert\" expected"; break;

-			case 64: s = "\"assume\" expected"; break;

-			case 65: s = "\"print\" expected"; break;

-			case 66: s = "\"parallel\" expected"; break;

-			case 67: s = "\"<==>\" expected"; break;

-			case 68: s = "\"\\u21d4\" expected"; break;

-			case 69: s = "\"==>\" expected"; break;

-			case 70: s = "\"\\u21d2\" expected"; break;

-			case 71: s = "\"&&\" expected"; break;

-			case 72: s = "\"\\u2227\" expected"; break;

-			case 73: s = "\"||\" expected"; break;

-			case 74: s = "\"\\u2228\" expected"; break;

-			case 75: s = "\"==\" expected"; break;

-			case 76: s = "\"<=\" expected"; break;

-			case 77: s = "\">=\" expected"; break;

-			case 78: s = "\"!=\" expected"; break;

-			case 79: s = "\"!!\" expected"; break;

-			case 80: s = "\"in\" expected"; break;

-			case 81: s = "\"!\" expected"; break;

-			case 82: s = "\"\\u2260\" expected"; break;

-			case 83: s = "\"\\u2264\" expected"; break;

-			case 84: s = "\"\\u2265\" expected"; break;

-			case 85: s = "\"+\" expected"; break;

-			case 86: s = "\"-\" expected"; break;

-			case 87: s = "\"/\" expected"; break;

-			case 88: s = "\"%\" expected"; break;

-			case 89: s = "\"\\u00ac\" expected"; break;

-			case 90: s = "\"false\" expected"; break;

-			case 91: s = "\"true\" expected"; break;

-			case 92: s = "\"null\" expected"; break;

-			case 93: s = "\"this\" expected"; break;

-			case 94: s = "\"fresh\" expected"; break;

-			case 95: s = "\"allocated\" expected"; break;

-			case 96: s = "\"old\" expected"; break;

-			case 97: s = "\"then\" expected"; break;

-			case 98: s = "\"..\" expected"; break;

-			case 99: s = "\"forall\" expected"; break;

-			case 100: s = "\"\\u2200\" expected"; break;

-			case 101: s = "\"exists\" expected"; break;

-			case 102: s = "\"\\u2203\" expected"; break;

-			case 103: s = "\"::\" expected"; break;

-			case 104: s = "\"\\u2022\" expected"; break;

-			case 105: s = "??? expected"; break;

-			case 106: s = "invalid Dafny"; break;

-			case 107: s = "this symbol not expected in ClassDecl"; break;

-			case 108: s = "this symbol not expected in DatatypeDecl"; break;

+			case 51: s = "\":|\" expected"; break;

+			case 52: s = "\"new\" expected"; break;

+			case 53: s = "\"[\" expected"; break;

+			case 54: s = "\"]\" expected"; break;

+			case 55: s = "\".\" expected"; break;

+			case 56: s = "\"choose\" expected"; break;

+			case 57: s = "\"if\" expected"; break;

+			case 58: s = "\"else\" expected"; break;

+			case 59: s = "\"case\" expected"; break;

+			case 60: s = "\"=>\" expected"; break;

+			case 61: s = "\"while\" expected"; break;

+			case 62: s = "\"invariant\" expected"; break;

+			case 63: s = "\"match\" expected"; break;

+			case 64: s = "\"assert\" expected"; break;

+			case 65: s = "\"assume\" expected"; break;

+			case 66: s = "\"print\" expected"; break;

+			case 67: s = "\"parallel\" expected"; break;

+			case 68: s = "\"<==>\" expected"; break;

+			case 69: s = "\"\\u21d4\" expected"; break;

+			case 70: s = "\"==>\" expected"; break;

+			case 71: s = "\"\\u21d2\" expected"; break;

+			case 72: s = "\"&&\" expected"; break;

+			case 73: s = "\"\\u2227\" expected"; break;

+			case 74: s = "\"||\" expected"; break;

+			case 75: s = "\"\\u2228\" expected"; break;

+			case 76: s = "\"==\" expected"; break;

+			case 77: s = "\"<=\" expected"; break;

+			case 78: s = "\">=\" expected"; break;

+			case 79: s = "\"!=\" expected"; break;

+			case 80: s = "\"!!\" expected"; break;

+			case 81: s = "\"in\" expected"; break;

+			case 82: s = "\"!\" expected"; break;

+			case 83: s = "\"\\u2260\" expected"; break;

+			case 84: s = "\"\\u2264\" expected"; break;

+			case 85: s = "\"\\u2265\" expected"; break;

+			case 86: s = "\"+\" expected"; break;

+			case 87: s = "\"-\" expected"; break;

+			case 88: s = "\"/\" expected"; break;

+			case 89: s = "\"%\" expected"; break;

+			case 90: s = "\"\\u00ac\" expected"; break;

+			case 91: s = "\"false\" expected"; break;

+			case 92: s = "\"true\" expected"; break;

+			case 93: s = "\"null\" expected"; break;

+			case 94: s = "\"this\" expected"; break;

+			case 95: s = "\"fresh\" expected"; break;

+			case 96: s = "\"allocated\" expected"; break;

+			case 97: s = "\"old\" expected"; break;

+			case 98: s = "\"then\" expected"; break;

+			case 99: s = "\"..\" expected"; break;

+			case 100: s = "\"forall\" expected"; break;

+			case 101: s = "\"\\u2200\" expected"; break;

+			case 102: s = "\"exists\" expected"; break;

+			case 103: s = "\"\\u2203\" expected"; break;

+			case 104: s = "\"::\" expected"; break;

+			case 105: s = "\"\\u2022\" expected"; break;

+			case 106: s = "??? expected"; break;

+			case 107: s = "invalid Dafny"; break;

+			case 108: s = "this symbol not expected in ClassDecl"; break;

 			case 109: s = "this symbol not expected in DatatypeDecl"; break;

-			case 110: s = "this symbol not expected in ArbitraryTypeDecl"; break;

-			case 111: s = "invalid ClassMemberDecl"; break;

-			case 112: s = "this symbol not expected in FieldDecl"; break;

+			case 110: s = "this symbol not expected in DatatypeDecl"; break;

+			case 111: s = "this symbol not expected in ArbitraryTypeDecl"; break;

+			case 112: s = "invalid ClassMemberDecl"; break;

 			case 113: s = "this symbol not expected in FieldDecl"; break;

-			case 114: s = "invalid FunctionDecl"; break;

+			case 114: s = "this symbol not expected in FieldDecl"; break;

 			case 115: s = "invalid FunctionDecl"; break;

 			case 116: s = "invalid FunctionDecl"; break;

-			case 117: s = "this symbol not expected in MethodDecl"; break;

-			case 118: s = "invalid MethodDecl"; break;

+			case 117: s = "invalid FunctionDecl"; break;

+			case 118: s = "this symbol not expected in MethodDecl"; break;

 			case 119: s = "invalid MethodDecl"; break;

-			case 120: s = "invalid TypeAndToken"; break;

-			case 121: s = "this symbol not expected in MethodSpec"; break;

+			case 120: s = "invalid MethodDecl"; break;

+			case 121: s = "invalid TypeAndToken"; break;

 			case 122: s = "this symbol not expected in MethodSpec"; break;

 			case 123: s = "this symbol not expected in MethodSpec"; break;

 			case 124: s = "this symbol not expected in MethodSpec"; break;

-			case 125: s = "invalid MethodSpec"; break;

-			case 126: s = "this symbol not expected in MethodSpec"; break;

-			case 127: s = "invalid MethodSpec"; break;

-			case 128: s = "invalid ReferenceType"; break;

-			case 129: s = "this symbol not expected in FunctionSpec"; break;

+			case 125: s = "this symbol not expected in MethodSpec"; break;

+			case 126: s = "invalid MethodSpec"; break;

+			case 127: s = "this symbol not expected in MethodSpec"; break;

+			case 128: s = "invalid MethodSpec"; break;

+			case 129: s = "invalid ReferenceType"; break;

 			case 130: s = "this symbol not expected in FunctionSpec"; break;

 			case 131: s = "this symbol not expected in FunctionSpec"; break;

 			case 132: s = "this symbol not expected in FunctionSpec"; break;

 			case 133: s = "this symbol not expected in FunctionSpec"; break;

-			case 134: s = "invalid FunctionSpec"; break;

-			case 135: s = "invalid PossiblyWildFrameExpression"; break;

-			case 136: s = "invalid PossiblyWildExpression"; break;

-			case 137: s = "this symbol not expected in OneStmt"; break;

-			case 138: s = "invalid OneStmt"; break;

-			case 139: s = "this symbol not expected in OneStmt"; break;

-			case 140: s = "invalid OneStmt"; break;

-			case 141: s = "invalid AssertStmt"; break;

-			case 142: s = "invalid UpdateStmt"; break;

-			case 143: s = "invalid IfStmt"; break;

-			case 144: s = "invalid IfStmt"; break;

-			case 145: s = "invalid WhileStmt"; break;

-			case 146: s = "invalid WhileStmt"; break;

-			case 147: s = "invalid Rhs"; break;

-			case 148: s = "invalid Lhs"; break;

-			case 149: s = "invalid Guard"; break;

-			case 150: s = "this symbol not expected in LoopSpec"; break;

-			case 151: s = "this symbol not expected in LoopSpec"; break;

+			case 134: s = "this symbol not expected in FunctionSpec"; break;

+			case 135: s = "invalid FunctionSpec"; break;

+			case 136: s = "invalid PossiblyWildFrameExpression"; break;

+			case 137: s = "invalid PossiblyWildExpression"; break;

+			case 138: s = "this symbol not expected in OneStmt"; break;

+			case 139: s = "invalid OneStmt"; break;

+			case 140: s = "this symbol not expected in OneStmt"; break;

+			case 141: s = "invalid OneStmt"; break;

+			case 142: s = "invalid AssertStmt"; break;

+			case 143: s = "invalid UpdateStmt"; break;

+			case 144: s = "invalid UpdateStmt"; break;

+			case 145: s = "invalid IfStmt"; break;

+			case 146: s = "invalid IfStmt"; break;

+			case 147: s = "invalid WhileStmt"; break;

+			case 148: s = "invalid WhileStmt"; break;

+			case 149: s = "invalid Rhs"; break;

+			case 150: s = "invalid Lhs"; break;

+			case 151: s = "invalid Guard"; break;

 			case 152: s = "this symbol not expected in LoopSpec"; break;

 			case 153: s = "this symbol not expected in LoopSpec"; break;

 			case 154: s = "this symbol not expected in LoopSpec"; break;

-			case 155: s = "this symbol not expected in Invariant"; break;

-			case 156: s = "invalid AttributeArg"; break;

-			case 157: s = "invalid EquivOp"; break;

-			case 158: s = "invalid ImpliesOp"; break;

-			case 159: s = "invalid AndOp"; break;

-			case 160: s = "invalid OrOp"; break;

-			case 161: s = "invalid RelOp"; break;

-			case 162: s = "invalid AddOp"; break;

-			case 163: s = "invalid UnaryExpression"; break;

-			case 164: s = "invalid MulOp"; break;

-			case 165: s = "invalid NegOp"; break;

-			case 166: s = "invalid EndlessExpression"; break;

-			case 167: s = "invalid Suffix"; break;

-			case 168: s = "invalid Suffix"; break;

+			case 155: s = "this symbol not expected in LoopSpec"; break;

+			case 156: s = "this symbol not expected in LoopSpec"; break;

+			case 157: s = "this symbol not expected in Invariant"; break;

+			case 158: s = "invalid AttributeArg"; break;

+			case 159: s = "invalid EquivOp"; break;

+			case 160: s = "invalid ImpliesOp"; break;

+			case 161: s = "invalid AndOp"; break;

+			case 162: s = "invalid OrOp"; break;

+			case 163: s = "invalid RelOp"; break;

+			case 164: s = "invalid AddOp"; break;

+			case 165: s = "invalid UnaryExpression"; break;

+			case 166: s = "invalid MulOp"; break;

+			case 167: s = "invalid NegOp"; break;

+			case 168: s = "invalid EndlessExpression"; break;

 			case 169: s = "invalid Suffix"; break;

-			case 170: s = "invalid DisplayExpr"; break;

-			case 171: s = "invalid MultiSetExpr"; break;

-			case 172: s = "invalid ConstAtomExpression"; break;

-			case 173: s = "invalid QuantifierGuts"; break;

-			case 174: s = "invalid Forall"; break;

-			case 175: s = "invalid Exists"; break;

-			case 176: s = "invalid QSep"; break;

+			case 170: s = "invalid Suffix"; break;

+			case 171: s = "invalid Suffix"; break;

+			case 172: s = "invalid DisplayExpr"; break;

+			case 173: s = "invalid MultiSetExpr"; break;

+			case 174: s = "invalid ConstAtomExpression"; break;

+			case 175: s = "invalid QuantifierGuts"; break;

+			case 176: s = "invalid Forall"; break;

+			case 177: s = "invalid Exists"; break;

+			case 178: s = "invalid QSep"; break;

 

 			default: s = "error " + n; break;

 		}

diff --git a/Dafny/Printer.cs b/Dafny/Printer.cs
index 28ce83f4..015bd490 100644
--- a/Dafny/Printer.cs
+++ b/Dafny/Printer.cs
@@ -595,23 +595,15 @@ namespace Microsoft.Dafny {
         Indent(indent);

         wr.Write("}");

 

-      } else if (stmt is UpdateStmt) {

-        var s = (UpdateStmt)stmt;

+      } else if (stmt is ConcreteUpdateStatement) {

+        var s = (ConcreteUpdateStatement)stmt;

         string sep = "";

         foreach (var lhs in s.Lhss) {

           wr.Write(sep);

           PrintExpression(lhs);

           sep = ", ";

         }

-        if (s.Lhss.Count != 0) {

-          sep = " := ";

-        }

-        foreach (var rhs in s.Rhss) {

-          wr.Write(sep);

-          PrintRhs(rhs);

-          sep = ", ";

-        }

-

+        PrintUpdateRHS(s);

         wr.Write(";");

 

       } else if (stmt is VarDeclStmt) {

@@ -627,13 +619,7 @@ namespace Microsoft.Dafny {
           sep = ", ";

         }

         if (s.Update != null) {

-          wr.Write(" := ");

-          sep = "";

-          foreach (var rhs in s.Update.Rhss) {

-            wr.Write(sep);

-            PrintRhs(rhs);

-            sep = ", ";

-          }

+          PrintUpdateRHS(s.Update);

         }

         wr.Write(";");

 

@@ -657,6 +643,31 @@ namespace Microsoft.Dafny {
       }

     }

 

+    /// <summary>

+    /// Does not print LHS

+    /// </summary>

+    void PrintUpdateRHS(ConcreteUpdateStatement s) {

+      Contract.Requires(s != null);

+      if (s is UpdateStmt) {

+        var update = (UpdateStmt)s;

+        if (update.Lhss.Count != 0) {

+          wr.Write(" := ");

+        }

+        var sep = "";

+        foreach (var rhs in update.Rhss) {

+          wr.Write(sep);

+          PrintRhs(rhs);

+          sep = ", ";

+        }

+      } else if (s is AssignSuchThatStmt) {

+        var update = (AssignSuchThatStmt)s;

+        wr.Write(" :| ");

+        PrintExpression(update.Assume.Expr);

+      } else {

+        Contract.Assert(s == null);  // otherwise, unknown type

+      }

+    }

+

     void PrintIfStatement(int indent, IfStmt s, bool omitGuard) {

       while (true) {

         if (omitGuard) {

diff --git a/Dafny/RefinementTransformer.cs b/Dafny/RefinementTransformer.cs
index 36ae8f22..f3e54b01 100644
--- a/Dafny/RefinementTransformer.cs
+++ b/Dafny/RefinementTransformer.cs
@@ -473,13 +473,17 @@ namespace Microsoft.Dafny {
         r = new MatchStmt(Tok(s.Tok), CloneExpr(s.Source),

           s.Cases.ConvertAll(c => new MatchCaseStmt(Tok(c.tok), c.Id, c.Arguments.ConvertAll(CloneBoundVar), c.Body.ConvertAll(CloneStmt))));

 

+      } else if (stmt is AssignSuchThatStmt) {

+        var s = (AssignSuchThatStmt)stmt;

+        r = new AssignSuchThatStmt(Tok(s.Tok), s.Lhss.ConvertAll(CloneExpr), CloneExpr(s.Assume.Expr));

+

       } else if (stmt is UpdateStmt) {

         var s = (UpdateStmt)stmt;

         r = new UpdateStmt(Tok(s.Tok), s.Lhss.ConvertAll(CloneExpr), s.Rhss.ConvertAll(CloneRHS), s.CanMutateKnownState);

 

       } else if (stmt is VarDeclStmt) {

         var s = (VarDeclStmt)stmt;

-        r = new VarDeclStmt(Tok(s.Tok), s.Lhss.ConvertAll(c => (VarDecl)CloneStmt(c)), (UpdateStmt)CloneStmt(s.Update));

+        r = new VarDeclStmt(Tok(s.Tok), s.Lhss.ConvertAll(c => (VarDecl)CloneStmt(c)), (ConcreteUpdateStatement)CloneStmt(s.Update));

 

       } else {

         Contract.Assert(false); throw new cce.UnreachableException();  // unexpected statement

diff --git a/Dafny/Resolver.cs b/Dafny/Resolver.cs
index b259e426..93ed3b4a 100644
--- a/Dafny/Resolver.cs
+++ b/Dafny/Resolver.cs
@@ -1308,8 +1308,8 @@ namespace Microsoft.Dafny {
         else {// this is a regular return statement.

           s.hiddenUpdate = null;

         }

-      } else if (stmt is UpdateStmt) {

-        ResolveUpdateStmt((UpdateStmt)stmt, specContextOnly, method);

+      } else if (stmt is ConcreteUpdateStatement) {

+        ResolveUpdateStmt((ConcreteUpdateStatement)stmt, specContextOnly, method);

       } else if (stmt is VarDeclStmt) {

         var s = (VarDeclStmt)stmt;

         foreach (var vd in s.Lhss) {

@@ -1725,7 +1725,7 @@ namespace Microsoft.Dafny {
       }

     }

 

-    private void ResolveUpdateStmt(UpdateStmt s, bool specContextOnly, Method method)

+    private void ResolveUpdateStmt(ConcreteUpdateStatement s, bool specContextOnly, Method method)

     {

       int prevErrorCount = ErrorCount;

       // First, resolve all LHS's and expression-looking RHS's.

@@ -1743,32 +1743,38 @@ namespace Microsoft.Dafny {
       }

       IToken firstEffectfulRhs = null;

       CallRhs callRhs = null;

+      var update = s as UpdateStmt;

       // Resolve RHSs

-      foreach (var rhs in s.Rhss) {

-        bool isEffectful;

-        if (rhs is TypeRhs) {

-          var tr = (TypeRhs)rhs;

-          ResolveTypeRhs(tr, s, specContextOnly, method);

-          isEffectful = tr.InitCall != null;

-        } else if (rhs is HavocRhs) {

-          isEffectful = false;

-        } else {

-          var er = (ExprRhs)rhs;

-          if (er.Expr is IdentifierSequence) {

-            var cRhs = ResolveIdentifierSequence((IdentifierSequence)er.Expr, true, true);

-            isEffectful = cRhs != null;

-            callRhs = callRhs ?? cRhs;

-          } else if (er.Expr is FunctionCallExpr) {

-            var cRhs = ResolveFunctionCallExpr((FunctionCallExpr)er.Expr, true, true);

-            isEffectful = cRhs != null;

-            callRhs = callRhs ?? cRhs;

-          } else {

-            ResolveExpression(er.Expr, true);

+      if (update == null) {

+        var suchThat = (AssignSuchThatStmt)s;  // this is the other possible subclass

+        s.ResolvedStatements.Add(suchThat.Assume);

+      } else {

+        foreach (var rhs in update.Rhss) {

+          bool isEffectful;

+          if (rhs is TypeRhs) {

+            var tr = (TypeRhs)rhs;

+            ResolveTypeRhs(tr, s, specContextOnly, method);

+            isEffectful = tr.InitCall != null;

+          } else if (rhs is HavocRhs) {

             isEffectful = false;

+          } else {

+            var er = (ExprRhs)rhs;

+            if (er.Expr is IdentifierSequence) {

+              var cRhs = ResolveIdentifierSequence((IdentifierSequence)er.Expr, true, true);

+              isEffectful = cRhs != null;

+              callRhs = callRhs ?? cRhs;

+            } else if (er.Expr is FunctionCallExpr) {

+              var cRhs = ResolveFunctionCallExpr((FunctionCallExpr)er.Expr, true, true);

+              isEffectful = cRhs != null;

+              callRhs = callRhs ?? cRhs;

+            } else {

+              ResolveExpression(er.Expr, true);

+              isEffectful = false;

+            }

+          }

+          if (isEffectful && firstEffectfulRhs == null) {

+            firstEffectfulRhs = rhs.Tok;

           }

-        }

-        if (isEffectful && firstEffectfulRhs == null) {

-          firstEffectfulRhs = rhs.Tok;

         }

       }

       // check for duplicate identifiers on the left (full duplication checking for references and the like is done during verification)

@@ -1784,67 +1790,69 @@ namespace Microsoft.Dafny {
         }

       }

 

-      // figure out what kind of UpdateStmt this is

-      if (firstEffectfulRhs == null) {

-        if (s.Lhss.Count == 0) {

-          Contract.Assert(s.Rhss.Count == 1);  // guaranteed by the parser

-          Error(s, "expected method call, found expression");

-        } else if (s.Lhss.Count != s.Rhss.Count) {

-          Error(s, "the number of left-hand sides ({0}) and right-hand sides ({1}) must match for a multi-assignment", s.Lhss.Count, s.Rhss.Count);

-        } else if (arrayRangeLhs != null && s.Lhss.Count != 1) {

-          Error(arrayRangeLhs, "array-range may not be used as LHS of multi-assignment; use separate assignment statements for each array-range assignment");

-        } else if (ErrorCount == prevErrorCount) {

-          // add the statements here in a sequence, but don't use that sequence later for translation (instead, should translated properly as multi-assignment)

-          for (int i = 0; i < s.Lhss.Count; i++) {

-            var a = new AssignStmt(s.Tok, s.Lhss[i].Resolved, s.Rhss[i]);

-            s.ResolvedStatements.Add(a);

-          }

-        }

-

-      } else if (s.CanMutateKnownState) {

-        if (1 < s.Rhss.Count) {

-          Error(firstEffectfulRhs, "cannot have effectful parameter in multi-return statement.");

-        } else { // it might be ok, if it is a TypeRhs

-          Contract.Assert(s.Rhss.Count == 1);

-          if (callRhs != null) {

-            Error(callRhs.Tok, "cannot have method call in return statement.");

-          } else {

-            // we have a TypeRhs

-            Contract.Assert(s.Rhss[0] is TypeRhs);

-            var tr = (TypeRhs)s.Rhss[0];

-            Contract.Assert(tr.InitCall != null); // there were effects, so this must have been a call.

-            if (tr.CanAffectPreviouslyKnownExpressions) {

-              Error(tr.Tok, "can only have initialization methods which modify at most 'this'.");

+      if (update != null) {

+        // figure out what kind of UpdateStmt this is

+        if (firstEffectfulRhs == null) {

+          if (s.Lhss.Count == 0) {

+            Contract.Assert(update.Rhss.Count == 1);  // guaranteed by the parser

+            Error(s, "expected method call, found expression");

+          } else if (s.Lhss.Count != update.Rhss.Count) {

+            Error(s, "the number of left-hand sides ({0}) and right-hand sides ({1}) must match for a multi-assignment", s.Lhss.Count, update.Rhss.Count);

+          } else if (arrayRangeLhs != null && s.Lhss.Count != 1) {

+            Error(arrayRangeLhs, "array-range may not be used as LHS of multi-assignment; use separate assignment statements for each array-range assignment");

+          } else if (ErrorCount == prevErrorCount) {

+            // add the statements here in a sequence, but don't use that sequence later for translation (instead, should translated properly as multi-assignment)

+            for (int i = 0; i < s.Lhss.Count; i++) {

+              var a = new AssignStmt(s.Tok, s.Lhss[i].Resolved, update.Rhss[i]);

+              s.ResolvedStatements.Add(a);

             }

-            var a = new AssignStmt(s.Tok, s.Lhss[0].Resolved, tr);

-            s.ResolvedStatements.Add(a);

           }

-        }

 

-      } else {

-        // if there was an effectful RHS, that must be the only RHS

-        if (s.Rhss.Count != 1) {

-          Error(firstEffectfulRhs, "an update statement is allowed an effectful RHS only if there is just one RHS");

-        } else if (arrayRangeLhs != null) {

-          Error(arrayRangeLhs, "Assignment to range of array elements must have a simple expression RHS; try using a temporary local variable");

-        } else if (callRhs == null) {

-          // must be a single TypeRhs

-          if (s.Lhss.Count != 1) {

-            Contract.Assert(2 <= s.Lhss.Count);  // the parser allows 0 Lhss only if the whole statement looks like an expression (not a TypeRhs)

-            Error(s.Lhss[1].tok, "the number of left-hand sides ({0}) and right-hand sides ({1}) must match for a multi-assignment", s.Lhss.Count, s.Rhss.Count);

-          } else if (ErrorCount == prevErrorCount) {

-            var a = new AssignStmt(s.Tok, s.Lhss[0].Resolved, s.Rhss[0]);

-            s.ResolvedStatements.Add(a);

+        } else if (update.CanMutateKnownState) {

+          if (1 < update.Rhss.Count) {

+            Error(firstEffectfulRhs, "cannot have effectful parameter in multi-return statement.");

+          } else { // it might be ok, if it is a TypeRhs

+            Contract.Assert(update.Rhss.Count == 1);

+            if (callRhs != null) {

+              Error(callRhs.Tok, "cannot have method call in return statement.");

+            } else {

+              // we have a TypeRhs

+              Contract.Assert(update.Rhss[0] is TypeRhs);

+              var tr = (TypeRhs)update.Rhss[0];

+              Contract.Assert(tr.InitCall != null); // there were effects, so this must have been a call.

+              if (tr.CanAffectPreviouslyKnownExpressions) {

+                Error(tr.Tok, "can only have initialization methods which modify at most 'this'.");

+              }

+              var a = new AssignStmt(s.Tok, s.Lhss[0].Resolved, tr);

+              s.ResolvedStatements.Add(a);

+            }

           }

+

         } else {

-          // a call statement

-          if (ErrorCount == prevErrorCount) {

-            var resolvedLhss = new List<Expression>();

-            foreach (var ll in s.Lhss) {

-              resolvedLhss.Add(ll.Resolved);

+          // if there was an effectful RHS, that must be the only RHS

+          if (update.Rhss.Count != 1) {

+            Error(firstEffectfulRhs, "an update statement is allowed an effectful RHS only if there is just one RHS");

+          } else if (arrayRangeLhs != null) {

+            Error(arrayRangeLhs, "Assignment to range of array elements must have a simple expression RHS; try using a temporary local variable");

+          } else if (callRhs == null) {

+            // must be a single TypeRhs

+            if (s.Lhss.Count != 1) {

+              Contract.Assert(2 <= s.Lhss.Count);  // the parser allows 0 Lhss only if the whole statement looks like an expression (not a TypeRhs)

+              Error(s.Lhss[1].tok, "the number of left-hand sides ({0}) and right-hand sides ({1}) must match for a multi-assignment", s.Lhss.Count, update.Rhss.Count);

+            } else if (ErrorCount == prevErrorCount) {

+              var a = new AssignStmt(s.Tok, s.Lhss[0].Resolved, update.Rhss[0]);

+              s.ResolvedStatements.Add(a);

+            }

+          } else {

+            // a call statement

+            if (ErrorCount == prevErrorCount) {

+              var resolvedLhss = new List<Expression>();

+              foreach (var ll in s.Lhss) {

+                resolvedLhss.Add(ll.Resolved);

+              }

+              var a = new CallStmt(callRhs.Tok, resolvedLhss, callRhs.Receiver, callRhs.MethodName, callRhs.Args);

+              s.ResolvedStatements.Add(a);

             }

-            var a = new CallStmt(callRhs.Tok, resolvedLhss, callRhs.Receiver, callRhs.MethodName, callRhs.Args);

-            s.ResolvedStatements.Add(a);

           }

         }

       }

diff --git a/Dafny/Rewriter.cs b/Dafny/Rewriter.cs
index addcce0a..26ec496e 100644
--- a/Dafny/Rewriter.cs
+++ b/Dafny/Rewriter.cs
@@ -296,8 +296,8 @@ namespace Microsoft.Dafny
       if (s is AssignStmt) {

         var ss = (AssignStmt)s;

         return ss.Lhs.Resolved is IdentifierExpr;

-      } else if (s is UpdateStmt) {

-        var ss = (UpdateStmt)s;

+      } else if (s is ConcreteUpdateStatement) {

+        var ss = (ConcreteUpdateStatement)s;

         return ss.Lhss.TrueForAll(e => e.Resolved is IdentifierExpr);

       } else if (s is CallStmt) {

         return false;

diff --git a/Dafny/Scanner.cs b/Dafny/Scanner.cs
index 3e021fa5..ca2ae13c 100644
--- a/Dafny/Scanner.cs
+++ b/Dafny/Scanner.cs
@@ -211,8 +211,8 @@ public class UTF8Buffer: Buffer {
 public class Scanner {

 	const char EOL = '\n';

 	const int eofSym = 0; /* pdt */

-	const int maxT = 105;

-	const int noSym = 105;

+	const int maxT = 106;

+	const int noSym = 106;

 

 

 	[ContractInvariantMethod]

@@ -258,39 +258,39 @@ public class Scanner {
 		for (int i = 48; i <= 57; ++i) start[i] = 7;

 		for (int i = 34; i <= 34; ++i) start[i] = 8;

 		start[97] = 12; 

-		start[58] = 55; 

+		start[58] = 56; 

 		start[123] = 10; 

 		start[125] = 11; 

-		start[61] = 56; 

-		start[124] = 57; 

+		start[61] = 57; 

+		start[124] = 58; 

 		start[59] = 19; 

 		start[44] = 20; 

-		start[60] = 58; 

-		start[62] = 59; 

-		start[46] = 60; 

+		start[60] = 59; 

+		start[62] = 60; 

+		start[46] = 61; 

 		start[40] = 22; 

 		start[41] = 23; 

 		start[42] = 24; 

 		start[96] = 25; 

-		start[91] = 27; 

-		start[93] = 28; 

-		start[8660] = 32; 

-		start[8658] = 34; 

-		start[38] = 35; 

-		start[8743] = 37; 

-		start[8744] = 39; 

-		start[33] = 61; 

-		start[8800] = 43; 

-		start[8804] = 44; 

-		start[8805] = 45; 

-		start[43] = 46; 

-		start[45] = 47; 

-		start[47] = 48; 

-		start[37] = 49; 

-		start[172] = 50; 

-		start[8704] = 51; 

-		start[8707] = 52; 

-		start[8226] = 54; 

+		start[91] = 28; 

+		start[93] = 29; 

+		start[8660] = 33; 

+		start[8658] = 35; 

+		start[38] = 36; 

+		start[8743] = 38; 

+		start[8744] = 40; 

+		start[33] = 62; 

+		start[8800] = 44; 

+		start[8804] = 45; 

+		start[8805] = 46; 

+		start[43] = 47; 

+		start[45] = 48; 

+		start[47] = 49; 

+		start[37] = 50; 

+		start[172] = 51; 

+		start[8704] = 52; 

+		start[8707] = 53; 

+		start[8226] = 55; 

 		start[Buffer.EOF] = -1;

 

 	}

@@ -519,29 +519,29 @@ public class Scanner {
 			case "label": t.kind = 47; break;

 			case "break": t.kind = 48; break;

 			case "return": t.kind = 49; break;

-			case "new": t.kind = 51; break;

-			case "choose": t.kind = 55; break;

-			case "if": t.kind = 56; break;

-			case "else": t.kind = 57; break;

-			case "case": t.kind = 58; break;

-			case "while": t.kind = 60; break;

-			case "invariant": t.kind = 61; break;

-			case "match": t.kind = 62; break;

-			case "assert": t.kind = 63; break;

-			case "assume": t.kind = 64; break;

-			case "print": t.kind = 65; break;

-			case "parallel": t.kind = 66; break;

-			case "in": t.kind = 80; break;

-			case "false": t.kind = 90; break;

-			case "true": t.kind = 91; break;

-			case "null": t.kind = 92; break;

-			case "this": t.kind = 93; break;

-			case "fresh": t.kind = 94; break;

-			case "allocated": t.kind = 95; break;

-			case "old": t.kind = 96; break;

-			case "then": t.kind = 97; break;

-			case "forall": t.kind = 99; break;

-			case "exists": t.kind = 101; break;

+			case "new": t.kind = 52; break;

+			case "choose": t.kind = 56; break;

+			case "if": t.kind = 57; break;

+			case "else": t.kind = 58; break;

+			case "case": t.kind = 59; break;

+			case "while": t.kind = 61; break;

+			case "invariant": t.kind = 62; break;

+			case "match": t.kind = 63; break;

+			case "assert": t.kind = 64; break;

+			case "assume": t.kind = 65; break;

+			case "print": t.kind = 66; break;

+			case "parallel": t.kind = 67; break;

+			case "in": t.kind = 81; break;

+			case "false": t.kind = 91; break;

+			case "true": t.kind = 92; break;

+			case "null": t.kind = 93; break;

+			case "this": t.kind = 94; break;

+			case "fresh": t.kind = 95; break;

+			case "allocated": t.kind = 96; break;

+			case "old": t.kind = 97; break;

+			case "then": t.kind = 98; break;

+			case "forall": t.kind = 100; break;

+			case "exists": t.kind = 102; break;

 			default: break;

 		}

 	}

@@ -663,16 +663,16 @@ public class Scanner {
 			case 26:

 				{t.kind = 50; break;}

 			case 27:

-				{t.kind = 52; break;}

+				{t.kind = 51; break;}

 			case 28:

 				{t.kind = 53; break;}

 			case 29:

-				{t.kind = 59; break;}

+				{t.kind = 54; break;}

 			case 30:

-				if (ch == '>') {AddCh(); goto case 31;}

-				else {goto case 0;}

+				{t.kind = 60; break;}

 			case 31:

-				{t.kind = 67; break;}

+				if (ch == '>') {AddCh(); goto case 32;}

+				else {goto case 0;}

 			case 32:

 				{t.kind = 68; break;}

 			case 33:

@@ -680,10 +680,10 @@ public class Scanner {
 			case 34:

 				{t.kind = 70; break;}

 			case 35:

-				if (ch == '&') {AddCh(); goto case 36;}

-				else {goto case 0;}

-			case 36:

 				{t.kind = 71; break;}

+			case 36:

+				if (ch == '&') {AddCh(); goto case 37;}

+				else {goto case 0;}

 			case 37:

 				{t.kind = 72; break;}

 			case 38:

@@ -691,13 +691,13 @@ public class Scanner {
 			case 39:

 				{t.kind = 74; break;}

 			case 40:

-				{t.kind = 77; break;}

+				{t.kind = 75; break;}

 			case 41:

 				{t.kind = 78; break;}

 			case 42:

 				{t.kind = 79; break;}

 			case 43:

-				{t.kind = 82; break;}

+				{t.kind = 80; break;}

 			case 44:

 				{t.kind = 83; break;}

 			case 45:

@@ -713,56 +713,59 @@ public class Scanner {
 			case 50:

 				{t.kind = 89; break;}

 			case 51:

-				{t.kind = 100; break;}

+				{t.kind = 90; break;}

 			case 52:

-				{t.kind = 102; break;}

+				{t.kind = 101; break;}

 			case 53:

 				{t.kind = 103; break;}

 			case 54:

 				{t.kind = 104; break;}

 			case 55:

+				{t.kind = 105; break;}

+			case 56:

 				recEnd = pos; recKind = 5;

 				if (ch == '=') {AddCh(); goto case 26;}

-				else if (ch == ':') {AddCh(); goto case 53;}

+				else if (ch == '|') {AddCh(); goto case 27;}

+				else if (ch == ':') {AddCh(); goto case 54;}

 				else {t.kind = 5; break;}

-			case 56:

+			case 57:

 				recEnd = pos; recKind = 16;

-				if (ch == '>') {AddCh(); goto case 29;}

-				else if (ch == '=') {AddCh(); goto case 62;}

+				if (ch == '>') {AddCh(); goto case 30;}

+				else if (ch == '=') {AddCh(); goto case 63;}

 				else {t.kind = 16; break;}

-			case 57:

+			case 58:

 				recEnd = pos; recKind = 17;

-				if (ch == '|') {AddCh(); goto case 38;}

+				if (ch == '|') {AddCh(); goto case 39;}

 				else {t.kind = 17; break;}

-			case 58:

+			case 59:

 				recEnd = pos; recKind = 22;

-				if (ch == '=') {AddCh(); goto case 63;}

+				if (ch == '=') {AddCh(); goto case 64;}

 				else {t.kind = 22; break;}

-			case 59:

+			case 60:

 				recEnd = pos; recKind = 23;

-				if (ch == '=') {AddCh(); goto case 40;}

+				if (ch == '=') {AddCh(); goto case 41;}

 				else {t.kind = 23; break;}

-			case 60:

-				recEnd = pos; recKind = 54;

-				if (ch == '.') {AddCh(); goto case 64;}

-				else {t.kind = 54; break;}

 			case 61:

-				recEnd = pos; recKind = 81;

-				if (ch == '=') {AddCh(); goto case 41;}

-				else if (ch == '!') {AddCh(); goto case 42;}

-				else {t.kind = 81; break;}

+				recEnd = pos; recKind = 55;

+				if (ch == '.') {AddCh(); goto case 65;}

+				else {t.kind = 55; break;}

 			case 62:

-				recEnd = pos; recKind = 75;

-				if (ch == '>') {AddCh(); goto case 33;}

-				else {t.kind = 75; break;}

+				recEnd = pos; recKind = 82;

+				if (ch == '=') {AddCh(); goto case 42;}

+				else if (ch == '!') {AddCh(); goto case 43;}

+				else {t.kind = 82; break;}

 			case 63:

 				recEnd = pos; recKind = 76;

-				if (ch == '=') {AddCh(); goto case 30;}

+				if (ch == '>') {AddCh(); goto case 34;}

 				else {t.kind = 76; break;}

 			case 64:

-				recEnd = pos; recKind = 98;

+				recEnd = pos; recKind = 77;

+				if (ch == '=') {AddCh(); goto case 31;}

+				else {t.kind = 77; break;}

+			case 65:

+				recEnd = pos; recKind = 99;

 				if (ch == '.') {AddCh(); goto case 21;}

-				else {t.kind = 98; break;}

+				else {t.kind = 99; break;}

 

 		}

 		t.val = new String(tval, 0, tlen);

diff --git a/Dafny/Translator.cs b/Dafny/Translator.cs
index a285a577..29632ea4 100644
--- a/Dafny/Translator.cs
+++ b/Dafny/Translator.cs
@@ -3331,6 +3331,25 @@ namespace Microsoft.Dafny {
           TrStmt(s.hiddenUpdate, builder, locals, etran);

         }

         builder.Add(new Bpl.ReturnCmd(stmt.Tok));

+      } else if (stmt is AssignSuchThatStmt) {

+        var s = (AssignSuchThatStmt)stmt;

+        AddComment(builder, s, "assign-such-that statement");

+        // treat like a parallel havoc, followed by an assume

+        // Here comes the havoc part

+        var lhss = new List<Expression>();

+        var havocRhss = new List<AssignmentRhs>();

+        foreach (var lhs in s.Lhss) {

+          lhss.Add(lhs.Resolved);

+          havocRhss.Add(new HavocRhs(lhs.tok));  // note, a HavocRhs is constructed as already resolved

+        }

+        List<AssignToLhs> lhsBuilder;

+        List<Bpl.IdentifierExpr> bLhss;

+        ProcessLhss(lhss, false, builder, locals, etran, out lhsBuilder, out bLhss);

+        ProcessRhss(lhsBuilder, bLhss, lhss, havocRhss, builder, locals, etran);

+        // End by doing the assume

+        TrStmt(s.Assume, builder, locals, etran);

+        builder.Add(CaptureState(s.Tok));  // just do one capture state--here, at the very end (that is, don't do one before the assume)

+

       } else if (stmt is UpdateStmt) {

         var s = (UpdateStmt)stmt;

         // This UpdateStmt can be single-target assignment, a multi-assignment, a call statement, or

diff --git a/Test/dafny0/Answer b/Test/dafny0/Answer
index 9995c817..22c24816 100644
--- a/Test/dafny0/Answer
+++ b/Test/dafny0/Answer
@@ -247,8 +247,47 @@ SmallTests.dfy(408,10): Error BP5003: A postcondition might not hold on this ret
 SmallTests.dfy(411,41): Related location: This is the postcondition that might not hold.

 Execution trace:

     (0,0): anon6_Else

+SmallTests.dfy(561,12): Error: assertion violation

+Execution trace:

+    (0,0): anon0

+    (0,0): anon3_Then

+    (0,0): anon2

+SmallTests.dfy(575,20): Error: left-hand sides 0 and 1 may refer to the same location

+Execution trace:

+    (0,0): anon0

+    (0,0): anon27_Then

+    (0,0): anon28_Then

+    (0,0): anon4

+    (0,0): anon29_Then

+    (0,0): anon30_Then

+    (0,0): anon9

+    (0,0): anon31_Then

+    (0,0): anon32_Then

+    (0,0): anon12

+SmallTests.dfy(577,15): Error: left-hand sides 1 and 2 may refer to the same location

+Execution trace:

+    (0,0): anon0

+    (0,0): anon27_Then

+    SmallTests.dfy(570,18): anon28_Else

+    (0,0): anon4

+    (0,0): anon29_Else

+    (0,0): anon7

+    (0,0): anon30_Then

+    (0,0): anon9

+    (0,0): anon31_Else

+    (0,0): anon35_Then

+    (0,0): anon36_Then

+    (0,0): anon37_Then

+    (0,0): anon22

+    (0,0): anon38_Then

+SmallTests.dfy(584,18): Error: target object may be null

+Execution trace:

+    (0,0): anon0

+SmallTests.dfy(597,10): Error: assertion violation

+Execution trace:

+    (0,0): anon0

 

-Dafny program verifier finished with 58 verified, 21 errors

+Dafny program verifier finished with 68 verified, 26 errors

 

 -------------------- Definedness.dfy --------------------

 Definedness.dfy(8,7): Error: possible division by zero

@@ -1598,8 +1637,47 @@ SmallTests.dfy(408,10): Error BP5003: A postcondition might not hold on this ret
 SmallTests.dfy(411,41): Related location: This is the postcondition that might not hold.

 Execution trace:

     (0,0): anon6_Else

+SmallTests.dfy(561,12): Error: assertion violation

+Execution trace:

+    (0,0): anon0

+    (0,0): anon3_Then

+    (0,0): anon2

+SmallTests.dfy(575,20): Error: left-hand sides 0 and 1 may refer to the same location

+Execution trace:

+    (0,0): anon0

+    (0,0): anon27_Then

+    (0,0): anon28_Then

+    (0,0): anon4

+    (0,0): anon29_Then

+    (0,0): anon30_Then

+    (0,0): anon9

+    (0,0): anon31_Then

+    (0,0): anon32_Then

+    (0,0): anon12

+SmallTests.dfy(577,15): Error: left-hand sides 1 and 2 may refer to the same location

+Execution trace:

+    (0,0): anon0

+    (0,0): anon27_Then

+    SmallTests.dfy(570,18): anon28_Else

+    (0,0): anon4

+    (0,0): anon29_Else

+    (0,0): anon7

+    (0,0): anon30_Then

+    (0,0): anon9

+    (0,0): anon31_Else

+    (0,0): anon35_Then

+    (0,0): anon36_Then

+    (0,0): anon37_Then

+    (0,0): anon22

+    (0,0): anon38_Then

+SmallTests.dfy(584,18): Error: target object may be null

+Execution trace:

+    (0,0): anon0

+SmallTests.dfy(597,10): Error: assertion violation

+Execution trace:

+    (0,0): anon0

 

-Dafny program verifier finished with 58 verified, 21 errors

+Dafny program verifier finished with 68 verified, 26 errors

 out.tmp.dfy(33,11): Error: index out of range

 Execution trace:

     (0,0): anon0

@@ -1707,8 +1785,47 @@ out.tmp.dfy(469,10): Error BP5003: A postcondition might not hold on this return
 out.tmp.dfy(470,41): Related location: This is the postcondition that might not hold.

 Execution trace:

     (0,0): anon6_Else

+out.tmp.dfy(507,12): Error: assertion violation

+Execution trace:

+    (0,0): anon0

+    (0,0): anon3_Then

+    (0,0): anon2

+out.tmp.dfy(521,20): Error: left-hand sides 0 and 1 may refer to the same location

+Execution trace:

+    (0,0): anon0

+    (0,0): anon27_Then

+    (0,0): anon28_Then

+    (0,0): anon4

+    (0,0): anon29_Then

+    (0,0): anon30_Then

+    (0,0): anon9

+    (0,0): anon31_Then

+    (0,0): anon32_Then

+    (0,0): anon12

+out.tmp.dfy(523,15): Error: left-hand sides 1 and 2 may refer to the same location

+Execution trace:

+    (0,0): anon0

+    (0,0): anon27_Then

+    out.tmp.dfy(516,18): anon28_Else

+    (0,0): anon4

+    (0,0): anon29_Else

+    (0,0): anon7

+    (0,0): anon30_Then

+    (0,0): anon9

+    (0,0): anon31_Else

+    (0,0): anon35_Then

+    (0,0): anon36_Then

+    (0,0): anon37_Then

+    (0,0): anon22

+    (0,0): anon38_Then

+out.tmp.dfy(530,18): Error: target object may be null

+Execution trace:

+    (0,0): anon0

+out.tmp.dfy(543,10): Error: assertion violation

+Execution trace:

+    (0,0): anon0

 

-Dafny program verifier finished with 58 verified, 21 errors

+Dafny program verifier finished with 68 verified, 26 errors

 

 -------------------- LetExpr.dfy --------------------

 LetExpr.dfy(5,12): Error: assertion violation

diff --git a/Test/dafny0/SmallTests.dfy b/Test/dafny0/SmallTests.dfy
index 914e228e..4d219cd3 100644
--- a/Test/dafny0/SmallTests.dfy
+++ b/Test/dafny0/SmallTests.dfy
@@ -535,3 +535,71 @@ static method TestNotNot()
 

   assert true == !(!true);

 }

+

+// ----------------------- Assign-such-that statements -------

+

+method AssignSuchThat0(a: int, b: int) returns (x: int, y: int)

+  ensures x == a && y == b;

+{

+  if (*) {

+    x, y :| a <= x < a + 1 && b + a <= y + a && y <= b;

+  } else {

+    var xx, yy :| a <= xx < a + 1 && b + a <= yy + a && yy <= b;

+    x, y := xx, yy;

+  }

+}

+

+method AssignSuchThat1(a: int, b: int) returns (x: int, y: int)

+{

+  var k :| 0 <= k < a - b;  // this acts like an 'assume 0 < a - b;'

+  assert b < a;

+  k :| k == old(2*k);  // note, the 'old' has no effect on local variables like k

+  assert k == 0;

+  var S := {2, 4, 7};

+  var T :| T <= S;

+  assert 3 !in T;

+  assert T == {};  // error: T may be larger

+}

+

+method AssignSuchThat2(i: int, j: int, ghost S: set<Node>)

+  modifies S;

+{

+  var n := new Node;

+  var a := new int[25];

+  var t;

+  if (0 <= i < j < 25) {

+    a[i], t, a[j], n.next, n :| true;

+  }

+  if (n != null && n.next != null) {

+    assume n in S && n.next in S;

+    n.next.next, n.next :| n != null && n.next != null && n.next.next == n.next;  // error: n.next may equal n (thus aliasing n.next.next and n.next)

+  } else if (0 <= i < 25 && 0 <= j < 25) {

+    t, a[i], a[j] :| t < a[i] < a[j];  // error: i may equal j (thus aliasing a[i] and a[j])

+  }

+}

+

+method AssignSuchThat3()

+{

+  var n := new Node;

+  n, n.next :| n.next == n;  // error: RHS is not well defined (RHS is evaluated after the havocking of the LHS)

+}

+

+method AssignSuchThat4()

+{

+  var n := new Node;

+  n, n.next :| n != null && n.next == n;  // that's the ticket

+}

+

+method AssignSuchThat5()

+{

+  var n := new Node;

+  n :| fresh(n);  // fine

+  assert false;  // error

+}

+

+method AssignSuchThat6()

+{

+  var n: Node;

+  n :| n != null && fresh(n);  // there is no non-null fresh object, so this amounts to 'assume false;'

+  assert false;  // no problemo

+}