diff --git a/core/descriptors/src/org/jetbrains/kotlin/renderer/Renderer.kt b/core/descriptors/src/org/jetbrains/kotlin/renderer/Renderer.kt
index e0efa96a459..222bad1ef21 100644
--- a/core/descriptors/src/org/jetbrains/kotlin/renderer/Renderer.kt
+++ b/core/descriptors/src/org/jetbrains/kotlin/renderer/Renderer.kt
@@ -14,11 +14,12 @@
  * limitations under the License.
  */
 
-package org.jetbrains.kotlin.renderer;
+package org.jetbrains.kotlin.renderer
 
-import org.jetbrains.annotations.NotNull;
-
-public interface Renderer<O> {
-    @NotNull
-    String render(@NotNull O object);
+public interface Renderer<in O> {
+    fun render(obj: O): String
+}
+
+fun <O> Renderer(block: (O) -> String) = object : Renderer<O> {
+    override fun render(obj: O) = block(obj)
 }