adapted and enhanced the dict operations to make them compatible with the new DictType

operator-dot.go

@@ -59,11 +59,11 @@ func evalDot(ctx ExprContext, self *term) (v any, err error) {
 		if index, err = verifyIndex(ctx, indexTerm, len(unboxedValue)); err == nil {
 			v = string(unboxedValue[index])
 		}
-	case map[any]any:
+	case *DictType:
 		var ok bool
 		var indexValue any
 		if indexValue, err = indexTerm.compute(ctx); err == nil {
-			if v, ok = unboxedValue[indexValue]; !ok {
+			if v, ok = (*unboxedValue)[indexValue]; !ok {
 				err = fmt.Errorf("key %v does not belong to the dictionary", rightValue)
 			}
 		}