diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScope.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScope.java
deleted file mode 100644
index 24f0f1eba61..00000000000
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScope.java
+++ /dev/null
@@ -1,69 +0,0 @@
-/*
- * 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.resolve.scopes;
-
-import com.google.common.collect.Multimap;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.jet.lang.descriptors.*;
-import org.jetbrains.jet.lang.resolve.name.Name;
-
-public interface WritableScope extends JetScope {
-    enum LockLevel {
-        WRITING,
-        BOTH,
-        READING,
-    }
-
-    WritableScope changeLockLevel(LockLevel lockLevel);
-
-    void addLabeledDeclaration(@NotNull DeclarationDescriptor descriptor);
-
-    void addVariableDescriptor(@NotNull VariableDescriptor variableDescriptor);
-
-    void addPropertyDescriptor(@NotNull VariableDescriptor propertyDescriptor);
-
-    void addFunctionDescriptor(@NotNull FunctionDescriptor functionDescriptor);
-
-    void addTypeParameterDescriptor(@NotNull TypeParameterDescriptor typeParameterDescriptor);
-
-    void addClassifierDescriptor(@NotNull ClassifierDescriptor classDescriptor);
-
-    void addClassifierAlias(@NotNull Name name, @NotNull ClassifierDescriptor classifierDescriptor);
-
-    void addPackageAlias(@NotNull Name name, @NotNull PackageViewDescriptor packageView);
-    
-    void addFunctionAlias(@NotNull Name name, @NotNull FunctionDescriptor functionDescriptor);
-    
-    void addVariableAlias(@NotNull Name name, @NotNull VariableDescriptor variableDescriptor);
-
-    @NotNull
-    Multimap<Name, DeclarationDescriptor> getDeclaredDescriptorsAccessibleBySimpleName();
-
-    void importScope(@NotNull JetScope imported);
-
-    void setImplicitReceiver(@NotNull ReceiverParameterDescriptor implicitReceiver);
-
-    void importClassifierAlias(@NotNull Name importedClassifierName, @NotNull ClassifierDescriptor classifierDescriptor);
-
-    void importPackageAlias(@NotNull Name aliasName, @NotNull PackageViewDescriptor packageView);
-    
-    void importFunctionAlias(@NotNull Name aliasName, @NotNull FunctionDescriptor functionDescriptor);
-    
-    void importVariableAlias(@NotNull Name aliasName, @NotNull VariableDescriptor variableDescriptor);
-
-    void clearImports();
-}
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScope.kt b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScope.kt
new file mode 100644
index 00000000000..e567779d4e0
--- /dev/null
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/scopes/WritableScope.kt
@@ -0,0 +1,67 @@
+/*
+ * 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.
+ * 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.resolve.scopes
+
+import com.google.common.collect.Multimap
+import org.jetbrains.jet.lang.descriptors.*
+import org.jetbrains.jet.lang.resolve.name.Name
+
+public trait WritableScope : JetScope {
+    public enum class LockLevel {
+        WRITING
+        BOTH
+        READING
+    }
+
+    public fun changeLockLevel(lockLevel: LockLevel): WritableScope
+
+    public fun addLabeledDeclaration(descriptor: DeclarationDescriptor)
+
+    public fun addVariableDescriptor(variableDescriptor: VariableDescriptor)
+
+    public fun addPropertyDescriptor(propertyDescriptor: VariableDescriptor)
+
+    public fun addFunctionDescriptor(functionDescriptor: FunctionDescriptor)
+
+    public fun addTypeParameterDescriptor(typeParameterDescriptor: TypeParameterDescriptor)
+
+    public fun addClassifierDescriptor(classDescriptor: ClassifierDescriptor)
+
+    public fun addClassifierAlias(name: Name, classifierDescriptor: ClassifierDescriptor)
+
+    public fun addPackageAlias(name: Name, packageView: PackageViewDescriptor)
+
+    public fun addFunctionAlias(name: Name, functionDescriptor: FunctionDescriptor)
+
+    public fun addVariableAlias(name: Name, variableDescriptor: VariableDescriptor)
+
+    public fun getDeclaredDescriptorsAccessibleBySimpleName(): Multimap<Name, DeclarationDescriptor>
+
+    public fun importScope(imported: JetScope)
+
+    public fun setImplicitReceiver(implicitReceiver: ReceiverParameterDescriptor)
+
+    public fun importClassifierAlias(importedClassifierName: Name, classifierDescriptor: ClassifierDescriptor)
+
+    public fun importPackageAlias(aliasName: Name, packageView: PackageViewDescriptor)
+
+    public fun importFunctionAlias(aliasName: Name, functionDescriptor: FunctionDescriptor)
+
+    public fun importVariableAlias(aliasName: Name, variableDescriptor: VariableDescriptor)
+
+    public fun clearImports()
+}