diff --git a/sources/zweic/Parser.scala b/sources/zweic/Parser.scala
index 0105d34..411e43c 100755
--- a/sources/zweic/Parser.scala
+++ b/sources/zweic/Parser.scala
@@ -108,7 +108,7 @@
     while (token == CLASS) {      
       classes = classDecl() :: classes;
     }
-    var main = expression();
+    val main = expression();
     return Program(classes.reverse, main);
   }
 
@@ -162,8 +162,8 @@
    * Formal = Type ident
    */
   private def formal(): Formal = {
-    var typ = type1();
-    var name = Name(chars);
+    val typ = type1();
+    val name = Name(chars);
     accept(IDENT);
     return Formal(name, typ);
   }
@@ -191,7 +191,7 @@
   private def type1(): TypeTree = token match {
     case INT => nextToken; return IntType();
     case NULLTYPE => nextToken; return NullType();
-    case IDENT => var name=Name(chars); nextToken; return ClassType(name);
+    case IDENT => val name=Name(chars); nextToken; return ClassType(name);
     case _ => error("'Int', 'Null' or identifier token"); return null;
   }
 
@@ -299,7 +299,7 @@
   * MyCmpExpression = SumExpression [ CompOp SumExpression ]
   */
   private def cmpExpression(): Expr = {
-	var left = sumExpression();
+	val left = sumExpression();
 	if ( token == EQ || token == NE || token == LT
 	|| token == GT || token == LE || token == GE ) {
 		val op = compOp();
@@ -314,7 +314,7 @@
   * MySumExpression = Term [ SumOp SumExpression ]
   */
   private def sumExpression(): Expr = {
-	var left = term();
+	val left = term();
 	if ( token == ADD || token == SUB ) {
 		return Binop(sumOp(), left, sumExpression());
 	} else {
@@ -322,9 +322,7 @@
 		  var right = sumExpression();
 		  left.brackets = true;
 		  right.brackets = true;
-		  var bol = Unop(Operators.NOT, left);
-		  var bor = Unop(Operators.NOT, right);
-		  var bo = Binop(Operators.AND, bol, bor);
+		  var bo = Binop(Operators.AND, Unop(Operators.NOT, left), Unop(Operators.NOT, right));
 		  bo.brackets = true;
 		  return Unop(Operators.NOT, bo);
 		} else {
@@ -427,7 +425,7 @@
   */
   private def params(): List[Expr] = {
 	accept(LPAREN);
-	var exprs = expressions();
+	val exprs = expressions();
 	accept(RPAREN);
 	return exprs;
   }