diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/ScriptCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/ScriptCodegen.java
index b52dcc3dd94..9c9592a86cf 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/ScriptCodegen.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/ScriptCodegen.java
@@ -30,7 +30,9 @@ import org.jetbrains.jet.codegen.state.GenerationState;
 import org.jetbrains.jet.lang.descriptors.ClassDescriptor;
 import org.jetbrains.jet.lang.descriptors.ScriptDescriptor;
 import org.jetbrains.jet.lang.descriptors.ValueParameterDescriptor;
-import org.jetbrains.jet.lang.psi.*;
+import org.jetbrains.jet.lang.psi.JetDeclaration;
+import org.jetbrains.jet.lang.psi.JetScript;
+import org.jetbrains.jet.lang.psi.JetTypeParameterListOwner;
 import org.jetbrains.jet.lang.resolve.BindingContext;
 
 import java.util.Collections;
@@ -63,13 +65,13 @@ public class ScriptCodegen extends MemberCodegen {
     }
 
     @NotNull
-    private JetScript scriptDeclaration;
+    private final JetScript scriptDeclaration;
 
     @NotNull
     private final ScriptContext context;
 
     @NotNull
-    private List<ScriptDescriptor> earlierScripts;
+    private final List<ScriptDescriptor> earlierScripts;
 
     private ScriptCodegen(
             @NotNull JetScript scriptDeclaration,
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/ScriptBodyResolver.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/ScriptBodyResolver.java
index 82824ac4626..3839ad5a7db 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/ScriptBodyResolver.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/ScriptBodyResolver.java
@@ -19,6 +19,7 @@ package org.jetbrains.jet.lang.resolve;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.descriptors.CallableMemberDescriptor;
 import org.jetbrains.jet.lang.descriptors.ScriptDescriptor;
+import org.jetbrains.jet.lang.descriptors.ScriptDescriptorImpl;
 import org.jetbrains.jet.lang.descriptors.SimpleFunctionDescriptor;
 import org.jetbrains.jet.lang.descriptors.impl.PropertyDescriptorImpl;
 import org.jetbrains.jet.lang.psi.JetDeclaration;
@@ -67,7 +68,7 @@ public class ScriptBodyResolver {
     public void resolveScriptBodies(@NotNull BodiesResolveContext c) {
         for (Map.Entry<JetScript, ScriptDescriptor> e : c.getScripts().entrySet()) {
             JetScript declaration = e.getKey();
-            ScriptDescriptor descriptor = e.getValue();
+            ScriptDescriptorImpl descriptor = (ScriptDescriptorImpl) e.getValue();
             WritableScope scope = c.getScriptScopes().get(declaration);
 
             // TODO: lock in resolveScriptDeclarations
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/ScriptHeaderResolver.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/ScriptHeaderResolver.java
index c1623218db1..0f56519e72e 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/ScriptHeaderResolver.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/ScriptHeaderResolver.java
@@ -19,16 +19,12 @@ package org.jetbrains.jet.lang.resolve;
 import com.google.common.collect.Lists;
 import com.intellij.openapi.util.Key;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.jet.lang.descriptors.ClassDescriptor;
-import org.jetbrains.jet.lang.descriptors.PackageFragmentDescriptor;
-import org.jetbrains.jet.lang.descriptors.ScriptDescriptor;
-import org.jetbrains.jet.lang.descriptors.ValueParameterDescriptor;
+import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.descriptors.annotations.Annotations;
 import org.jetbrains.jet.lang.descriptors.impl.ValueParameterDescriptorImpl;
 import org.jetbrains.jet.lang.parsing.JetScriptDefinition;
 import org.jetbrains.jet.lang.parsing.JetScriptDefinitionProvider;
 import org.jetbrains.jet.lang.psi.JetFile;
-import org.jetbrains.jet.lang.psi.JetPackageDirective;
 import org.jetbrains.jet.lang.psi.JetScript;
 import org.jetbrains.jet.lang.resolve.name.FqName;
 import org.jetbrains.jet.lang.resolve.name.Name;
@@ -115,7 +111,7 @@ public class ScriptHeaderResolver {
 
         FqName nameForScript = ScriptNameUtil.classNameForScript((JetFile) script.getContainingFile());
         Name className = nameForScript.shortName();
-        ScriptDescriptor scriptDescriptor = new ScriptDescriptor(ns, priority, outerScope, className);
+        ScriptDescriptor scriptDescriptor = new ScriptDescriptorImpl(ns, priority, outerScope, className);
 
         //WriteThroughScope scriptScope = new WriteThroughScope(
         //        outerScope, ns.getMemberScope(), new TraceBasedRedeclarationHandler(trace));
@@ -133,7 +129,7 @@ public class ScriptHeaderResolver {
     public void resolveScriptDeclarations(@NotNull TopDownAnalysisContext c) {
         for (Map.Entry<JetScript, ScriptDescriptor> e : c.getScripts().entrySet()) {
             JetScript declaration = e.getKey();
-            ScriptDescriptor descriptor = e.getValue();
+            ScriptDescriptorImpl descriptor = (ScriptDescriptorImpl) e.getValue();
             WritableScope scope = c.getScriptScopes().get(declaration);
 
             List<ValueParameterDescriptor> valueParameters = Lists.newArrayList();
diff --git a/core/descriptors/src/org/jetbrains/jet/lang/descriptors/ScriptDescriptor.java b/core/descriptors/src/org/jetbrains/jet/lang/descriptors/ScriptDescriptor.java
index 1c036910e12..46796b152b8 100644
--- a/core/descriptors/src/org/jetbrains/jet/lang/descriptors/ScriptDescriptor.java
+++ b/core/descriptors/src/org/jetbrains/jet/lang/descriptors/ScriptDescriptor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2013 JetBrains s.r.o.
+ * Copyright 2010-2014 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,173 +17,31 @@
 package org.jetbrains.jet.lang.descriptors;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.jet.lang.descriptors.annotations.Annotations;
-import org.jetbrains.jet.lang.descriptors.impl.*;
-import org.jetbrains.jet.lang.resolve.DescriptorFactory;
-import org.jetbrains.jet.lang.resolve.name.Name;
-import org.jetbrains.jet.lang.resolve.scopes.JetScope;
-import org.jetbrains.jet.lang.resolve.scopes.RedeclarationHandler;
-import org.jetbrains.jet.lang.resolve.scopes.WritableScope;
-import org.jetbrains.jet.lang.resolve.scopes.WritableScopeImpl;
-import org.jetbrains.jet.lang.resolve.scopes.receivers.ScriptReceiver;
+import org.jetbrains.jet.lang.descriptors.annotations.Annotated;
+import org.jetbrains.jet.lang.descriptors.impl.ScriptCodeDescriptor;
 import org.jetbrains.jet.lang.types.JetType;
-import org.jetbrains.jet.lang.types.TypeSubstitutor;
-import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns;
+import org.jetbrains.jet.lang.resolve.name.Name;
 
-import java.util.Collections;
-import java.util.HashSet;
 import java.util.List;
 
-// SCRIPT: Script declaration descriptor
-public class ScriptDescriptor extends DeclarationDescriptorNonRootImpl {
-    public static final String LAST_EXPRESSION_VALUE_FIELD_NAME = "rv";
-    private static final Name NAME = Name.special("<script>");
-
-    private final int priority;
-
-    private JetType returnType;
-    private List<ValueParameterDescriptor> valueParameters;
-
-    private final ScriptCodeDescriptor scriptCodeDescriptor = new ScriptCodeDescriptor(this);
-    private final ReceiverParameterDescriptor implicitReceiver = new ReceiverParameterDescriptorImpl(this,
-                                                                                                     // Putting Any here makes no sense,
-                                                                                                     // it is simply copied from someplace else
-                                                                                                     // during a refactoring
-                                                                                                     KotlinBuiltIns.getInstance().getAnyType(),
-                                                                                                     new ScriptReceiver(this));
-
-    private final ClassDescriptorImpl classDescriptor;
-
-    private final WritableScopeImpl classScope;
-
-    public ScriptDescriptor(
-            @NotNull DeclarationDescriptor containingDeclaration,
-            int priority,
-            @NotNull JetScope scriptScope,
-            @NotNull Name className
-    ) {
-        super(containingDeclaration, Annotations.EMPTY, NAME);
-        this.priority = priority;
-
-        classDescriptor = new ClassDescriptorImpl(containingDeclaration, className, Modality.FINAL,
-                                                  Collections.singleton(KotlinBuiltIns.getInstance().getAnyType()));
-        classScope = new WritableScopeImpl(scriptScope, containingDeclaration, RedeclarationHandler.DO_NOTHING, "script members");
-        classScope.changeLockLevel(WritableScope.LockLevel.BOTH);
-        classDescriptor.initialize(classScope, new HashSet<ConstructorDescriptor>(), null);
-    }
-
-    public void initialize(
-            @NotNull JetType returnType,
-            @NotNull List<? extends PropertyDescriptorImpl> properties,
-            @NotNull List<? extends FunctionDescriptor> functions
-    ) {
-        this.returnType = returnType;
-        scriptCodeDescriptor.initialize(implicitReceiver, valueParameters, returnType);
-
-        PropertyDescriptorImpl propertyDescriptor = PropertyDescriptorImpl.create(classDescriptor,
-                                                                                  Annotations.EMPTY,
-                                                                                  Modality.FINAL,
-                                                                                  Visibilities.PUBLIC,
-                                                                                  false,
-                                                                                  Name.identifier(LAST_EXPRESSION_VALUE_FIELD_NAME),
-                                                                                  CallableMemberDescriptor.Kind.DECLARATION);
-        propertyDescriptor.setType(
-                returnType,
-                Collections.<TypeParameterDescriptor>emptyList(),
-                classDescriptor.getThisAsReceiverParameter(),
-                ReceiverParameterDescriptor.NO_RECEIVER_PARAMETER);
-        propertyDescriptor.initialize(null, null);
-        classScope.addPropertyDescriptor(propertyDescriptor);
-
-        for (PropertyDescriptorImpl property : properties) {
-            initializeWithDefaultGetterSetter(property);
-            classScope.addPropertyDescriptor(property);
-        }
-
-        for (FunctionDescriptor function : functions) {
-            classScope.addFunctionDescriptor(function);
-        }
-    }
-
-    public static void initializeWithDefaultGetterSetter(PropertyDescriptorImpl propertyDescriptor) {
-        PropertyGetterDescriptorImpl getter = propertyDescriptor.getGetter();
-        if (getter == null && propertyDescriptor.getVisibility() != Visibilities.PRIVATE) {
-            getter = DescriptorFactory.createDefaultGetter(propertyDescriptor);
-            getter.initialize(propertyDescriptor.getType());
-        }
-
-        PropertySetterDescriptor setter = propertyDescriptor.getSetter();
-        if (setter == null && propertyDescriptor.isVar()) {
-            setter = DescriptorFactory.createDefaultSetter(propertyDescriptor);
-        }
-        propertyDescriptor.initialize(getter, setter);
-    }
-
-    public int getPriority() {
-        return priority;
-    }
+public interface ScriptDescriptor extends Annotated, DeclarationDescriptor, DeclarationDescriptorNonRoot {
+    String LAST_EXPRESSION_VALUE_FIELD_NAME = "rv";
+    Name NAME = Name.special("<script>");
 
     @NotNull
-    public JetType getReturnType() {
-        return returnType;
-    }
+    JetType getReturnType();
+
+    int getPriority();
 
     @NotNull
-    public List<ValueParameterDescriptor> getValueParameters() {
-        return valueParameters;
-    }
+    List<ValueParameterDescriptor> getValueParameters();
 
     @NotNull
-    public ScriptCodeDescriptor getScriptCodeDescriptor() {
-        return scriptCodeDescriptor;
-    }
+    ScriptCodeDescriptor getScriptCodeDescriptor();
 
     @NotNull
-    public ReceiverParameterDescriptor getThisAsReceiverParameter() {
-        return implicitReceiver;
-    }
-
-    @Override
-    public DeclarationDescriptor substitute(@NotNull TypeSubstitutor substitutor) {
-        throw new IllegalStateException("nothing to substitute in script");
-    }
-
-    @Override
-    public <R, D> R accept(DeclarationDescriptorVisitor<R, D> visitor, D data) {
-        return visitor.visitScriptDescriptor(this, data);
-    }
-
-    public void setValueParameters(@NotNull List<ValueParameterDescriptor> valueParameters) {
-        this.valueParameters = valueParameters;
-        ConstructorDescriptorImpl constructorDescriptor =
-                ConstructorDescriptorImpl.create(classDescriptor, Annotations.EMPTY, true)
-                        .initialize(Collections.<TypeParameterDescriptor>emptyList(), valueParameters, Visibilities.PUBLIC, false);
-        constructorDescriptor.setReturnType(classDescriptor.getDefaultType());
-
-        classDescriptor.getConstructors().add(constructorDescriptor);
-        classDescriptor.setPrimaryConstructor(constructorDescriptor);
-
-        for (ValueParameterDescriptor parameter : valueParameters) {
-            PropertyDescriptorImpl propertyDescriptor = PropertyDescriptorImpl.create(classDescriptor,
-                                                                                      Annotations.EMPTY,
-                                                                                      Modality.FINAL,
-                                                                                      Visibilities.PUBLIC,
-                                                                                      false,
-                                                                                      parameter.getName(),
-                                                                                      CallableMemberDescriptor.Kind.DECLARATION);
-            propertyDescriptor.setType(
-                    parameter.getType(),
-                    Collections.<TypeParameterDescriptor>emptyList(),
-                    classDescriptor.getThisAsReceiverParameter(), ReceiverParameterDescriptor.NO_RECEIVER_PARAMETER);
-            //PropertyGetterDescriptor getter = DescriptorResolver.createDefaultGetter(propertyDescriptor);
-            //getter.initialize(propertyDescriptor.getType());
-            propertyDescriptor.initialize(null, null);
-            classScope.addPropertyDescriptor(propertyDescriptor);
-        }
-    }
+    ReceiverParameterDescriptor getThisAsReceiverParameter();
 
     @NotNull
-    public ClassDescriptor getClassDescriptor() {
-        return classDescriptor;
-    }
+    ClassDescriptor getClassDescriptor();
 }
diff --git a/core/descriptors/src/org/jetbrains/jet/lang/descriptors/ScriptDescriptorImpl.java b/core/descriptors/src/org/jetbrains/jet/lang/descriptors/ScriptDescriptorImpl.java
new file mode 100644
index 00000000000..4407a0c1bd2
--- /dev/null
+++ b/core/descriptors/src/org/jetbrains/jet/lang/descriptors/ScriptDescriptorImpl.java
@@ -0,0 +1,193 @@
+/*
+ * Copyright 2010-2013 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.lang.descriptors;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.jet.lang.descriptors.annotations.Annotations;
+import org.jetbrains.jet.lang.descriptors.impl.*;
+import org.jetbrains.jet.lang.resolve.DescriptorFactory;
+import org.jetbrains.jet.lang.resolve.name.Name;
+import org.jetbrains.jet.lang.resolve.scopes.JetScope;
+import org.jetbrains.jet.lang.resolve.scopes.RedeclarationHandler;
+import org.jetbrains.jet.lang.resolve.scopes.WritableScope;
+import org.jetbrains.jet.lang.resolve.scopes.WritableScopeImpl;
+import org.jetbrains.jet.lang.resolve.scopes.receivers.ScriptReceiver;
+import org.jetbrains.jet.lang.types.JetType;
+import org.jetbrains.jet.lang.types.TypeSubstitutor;
+import org.jetbrains.jet.lang.types.lang.KotlinBuiltIns;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+
+// SCRIPT: Script declaration descriptor
+public class ScriptDescriptorImpl extends DeclarationDescriptorNonRootImpl implements ScriptDescriptor {
+
+    private final int priority;
+
+    private JetType returnType;
+    private List<ValueParameterDescriptor> valueParameters;
+
+    private final ScriptCodeDescriptor scriptCodeDescriptor = new ScriptCodeDescriptor(this);
+    private final ReceiverParameterDescriptor implicitReceiver = new ReceiverParameterDescriptorImpl(this,
+                                                                                                     // Putting Any here makes no sense,
+                                                                                                     // it is simply copied from someplace else
+                                                                                                     // during a refactoring
+                                                                                                     KotlinBuiltIns.getInstance().getAnyType(),
+                                                                                                     new ScriptReceiver(this));
+
+    private final ClassDescriptorImpl classDescriptor;
+
+    private final WritableScopeImpl classScope;
+
+    public ScriptDescriptorImpl(
+            @NotNull DeclarationDescriptor containingDeclaration,
+            int priority,
+            @NotNull JetScope scriptScope,
+            @NotNull Name className
+    ) {
+        super(containingDeclaration, Annotations.EMPTY, NAME);
+        this.priority = priority;
+
+        classDescriptor = new ClassDescriptorImpl(containingDeclaration, className, Modality.FINAL,
+                                                  Collections.singleton(KotlinBuiltIns.getInstance().getAnyType()));
+        classScope = new WritableScopeImpl(scriptScope, containingDeclaration, RedeclarationHandler.DO_NOTHING, "script members");
+        classScope.changeLockLevel(WritableScope.LockLevel.BOTH);
+        classDescriptor.initialize(classScope, new HashSet<ConstructorDescriptor>(), null);
+    }
+
+    public void initialize(
+            @NotNull JetType returnType,
+            @NotNull List<? extends PropertyDescriptorImpl> properties,
+            @NotNull List<? extends FunctionDescriptor> functions
+    ) {
+        this.returnType = returnType;
+        scriptCodeDescriptor.initialize(implicitReceiver, valueParameters, returnType);
+
+        PropertyDescriptorImpl propertyDescriptor = PropertyDescriptorImpl.create(classDescriptor,
+                                                                                  Annotations.EMPTY,
+                                                                                  Modality.FINAL,
+                                                                                  Visibilities.PUBLIC,
+                                                                                  false,
+                                                                                  Name.identifier(LAST_EXPRESSION_VALUE_FIELD_NAME),
+                                                                                  CallableMemberDescriptor.Kind.DECLARATION);
+        propertyDescriptor.setType(
+                returnType,
+                Collections.<TypeParameterDescriptor>emptyList(),
+                classDescriptor.getThisAsReceiverParameter(),
+                ReceiverParameterDescriptor.NO_RECEIVER_PARAMETER);
+        propertyDescriptor.initialize(null, null);
+        classScope.addPropertyDescriptor(propertyDescriptor);
+
+        for (PropertyDescriptorImpl property : properties) {
+            initializeWithDefaultGetterSetter(property);
+            classScope.addPropertyDescriptor(property);
+        }
+
+        for (FunctionDescriptor function : functions) {
+            classScope.addFunctionDescriptor(function);
+        }
+    }
+
+    public static void initializeWithDefaultGetterSetter(PropertyDescriptorImpl propertyDescriptor) {
+        PropertyGetterDescriptorImpl getter = propertyDescriptor.getGetter();
+        if (getter == null && propertyDescriptor.getVisibility() != Visibilities.PRIVATE) {
+            getter = DescriptorFactory.createDefaultGetter(propertyDescriptor);
+            getter.initialize(propertyDescriptor.getType());
+        }
+
+        PropertySetterDescriptor setter = propertyDescriptor.getSetter();
+        if (setter == null && propertyDescriptor.isVar()) {
+            setter = DescriptorFactory.createDefaultSetter(propertyDescriptor);
+        }
+        propertyDescriptor.initialize(getter, setter);
+    }
+
+    @Override
+    public int getPriority() {
+        return priority;
+    }
+
+    @Override
+    @NotNull
+    public JetType getReturnType() {
+        return returnType;
+    }
+
+    @Override
+    @NotNull
+    public List<ValueParameterDescriptor> getValueParameters() {
+        return valueParameters;
+    }
+
+    @Override
+    @NotNull
+    public ScriptCodeDescriptor getScriptCodeDescriptor() {
+        return scriptCodeDescriptor;
+    }
+
+    @Override
+    @NotNull
+    public ReceiverParameterDescriptor getThisAsReceiverParameter() {
+        return implicitReceiver;
+    }
+
+    @Override
+    public DeclarationDescriptor substitute(@NotNull TypeSubstitutor substitutor) {
+        throw new IllegalStateException("nothing to substitute in script");
+    }
+
+    @Override
+    public <R, D> R accept(DeclarationDescriptorVisitor<R, D> visitor, D data) {
+        return visitor.visitScriptDescriptor(this, data);
+    }
+
+    public void setValueParameters(@NotNull List<ValueParameterDescriptor> valueParameters) {
+        this.valueParameters = valueParameters;
+        ConstructorDescriptorImpl constructorDescriptor =
+                ConstructorDescriptorImpl.create(classDescriptor, Annotations.EMPTY, true)
+                        .initialize(Collections.<TypeParameterDescriptor>emptyList(), valueParameters, Visibilities.PUBLIC, false);
+        constructorDescriptor.setReturnType(classDescriptor.getDefaultType());
+
+        classDescriptor.getConstructors().add(constructorDescriptor);
+        classDescriptor.setPrimaryConstructor(constructorDescriptor);
+
+        for (ValueParameterDescriptor parameter : valueParameters) {
+            PropertyDescriptorImpl propertyDescriptor = PropertyDescriptorImpl.create(classDescriptor,
+                                                                                      Annotations.EMPTY,
+                                                                                      Modality.FINAL,
+                                                                                      Visibilities.PUBLIC,
+                                                                                      false,
+                                                                                      parameter.getName(),
+                                                                                      CallableMemberDescriptor.Kind.DECLARATION);
+            propertyDescriptor.setType(
+                    parameter.getType(),
+                    Collections.<TypeParameterDescriptor>emptyList(),
+                    classDescriptor.getThisAsReceiverParameter(), ReceiverParameterDescriptor.NO_RECEIVER_PARAMETER);
+            //PropertyGetterDescriptor getter = DescriptorResolver.createDefaultGetter(propertyDescriptor);
+            //getter.initialize(propertyDescriptor.getType());
+            propertyDescriptor.initialize(null, null);
+            classScope.addPropertyDescriptor(propertyDescriptor);
+        }
+    }
+
+    @Override
+    @NotNull
+    public ClassDescriptor getClassDescriptor() {
+        return classDescriptor;
+    }
+}