diff --git a/platform/platform-api/src/org/jetbrains/concurrency/AsyncPromise.java b/platform/platform-api/src/org/jetbrains/concurrency/AsyncPromise.java
index dbfabfc57c24..51a81a86bfb6 100644
--- a/platform/platform-api/src/org/jetbrains/concurrency/AsyncPromise.java
+++ b/platform/platform-api/src/org/jetbrains/concurrency/AsyncPromise.java
@@ -13,311 +13,263 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.jetbrains.concurrency;
+package org.jetbrains.concurrency
 
-import com.intellij.openapi.diagnostic.Logger;
-import com.intellij.openapi.util.Getter;
-import com.intellij.util.Consumer;
-import com.intellij.util.Function;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
+import com.intellij.openapi.diagnostic.Logger
+import com.intellij.openapi.util.Getter
+import com.intellij.util.Consumer
+import com.intellij.util.Function
+import java.util.*
 
-import java.util.ArrayList;
-import java.util.List;
+private val LOG = Logger.getInstance(AsyncPromise::class.java)
 
-public class AsyncPromise<T> extends Promise<T> implements Getter<T> {
-  private static final Logger LOG = Logger.getInstance(AsyncPromise.class);
+@SuppressWarnings("ThrowableResultOfMethodCallIgnored")
+val OBSOLETE_ERROR = Promise.createError("Obsolete")
 
-  @SuppressWarnings("ThrowableResultOfMethodCallIgnored")
-  public static final RuntimeException OBSOLETE_ERROR = Promise.createError("Obsolete");
+open class AsyncPromise<T> : Promise<T>(), Getter<T> {
+  @Volatile private var done: Consumer<in T>? = null
+  @Volatile private var rejected: Consumer<in Throwable>? = null
 
-  private volatile Consumer<? super T> done;
-  private volatile Consumer<? super Throwable> rejected;
+  @Volatile private var state: Promise.State = Promise.State.PENDING
 
-  protected volatile State state = State.PENDING;
   // result object or error message
-  private volatile Object result;
+  @Volatile private var result: Any? = null
 
-  @NotNull
-  @Override
-  public State getState() {
-    return state;
-  }
+  override fun getState() = state
 
-  @NotNull
-  @Override
-  public Promise<T> done(@NotNull Consumer<? super T> done) {
+  override fun done(done: Consumer<in T>): Promise<T> {
     if (isObsolete(done)) {
-      return this;
+      return this
     }
 
-    switch (state) {
-      case PENDING:
-        break;
-      case FULFILLED:
-        //noinspection unchecked
-        done.consume((T)result);
-        return this;
-      case REJECTED:
-        return this;
+    when (state) {
+      Promise.State.PENDING -> {
+      }
+      Promise.State.FULFILLED -> {
+        @Suppress("UNCHECKED_CAST")
+        done.consume(result as T?)
+        return this
+      }
+      Promise.State.REJECTED -> return this
     }
 
-    this.done = setHandler(this.done, done);
-    return this;
+    this.done = setHandler(this.done, done)
+    return this
   }
 
-  @NotNull
-  @Override
-  public Promise<T> rejected(@NotNull Consumer<Throwable> rejected) {
+  override fun rejected(rejected: Consumer<Throwable>): Promise<T> {
     if (isObsolete(rejected)) {
-      return this;
+      return this
     }
 
-    switch (state) {
-      case PENDING:
-        break;
-      case FULFILLED:
-        return this;
-      case REJECTED:
-        rejected.consume((Throwable)result);
-        return this;
+    when (state) {
+      Promise.State.PENDING -> {
+      }
+      Promise.State.FULFILLED -> return this
+      Promise.State.REJECTED -> {
+        rejected.consume(result as Throwable?)
+        return this
+      }
     }
 
-    this.rejected = setHandler(this.rejected, rejected);
-    return this;
+    this.rejected = setHandler(this.rejected, rejected)
+    return this
   }
 
-  @Override
-  public T get() {
-    //noinspection unchecked
-    return state == State.FULFILLED ? (T)result : null;
+  @Suppress("UNCHECKED_CAST")
+  override fun get() = if (state == Promise.State.FULFILLED) result as T? else null
+
+  override fun <SUB_RESULT> then(fulfilled: Function<in T, out SUB_RESULT>): Promise<SUB_RESULT> {
+    @Suppress("UNCHECKED_CAST")
+    when (state) {
+      Promise.State.PENDING -> {
+      }
+      Promise.State.FULFILLED -> return DonePromise<SUB_RESULT>(fulfilled.`fun`(result as T?))
+      Promise.State.REJECTED -> return rejectedPromise(result as Throwable)
+    }
+
+    val promise = AsyncPromise<SUB_RESULT>()
+    addHandlers(Consumer({ result ->
+                           promise.catchError {
+                             if (fulfilled is Obsolescent && fulfilled.isObsolete) {
+                               promise.setError(OBSOLETE_ERROR)
+                             }
+                             else {
+                               promise.setResult(fulfilled.`fun`(result))
+                             }
+                           }
+                         }), Consumer({ promise.setError(it) }))
+    return promise
   }
 
-  @SuppressWarnings("SynchronizeOnThis")
-  private static final class CompoundConsumer<T> implements Consumer<T> {
-    private List<Consumer<? super T>> consumers = new ArrayList<>();
+  override fun notify(child: AsyncPromise<in T>) {
+    LOG.assertTrue(child !== this)
 
-    public CompoundConsumer(@NotNull Consumer<? super T> c1, @NotNull Consumer<? super T> c2) {
-      synchronized (this) {
-        consumers.add(c1);
-        consumers.add(c2);
+    when (state) {
+      Promise.State.PENDING -> {
+      }
+      Promise.State.FULFILLED -> {
+        @Suppress("UNCHECKED_CAST")
+        child.setResult(result as T)
+        return
+      }
+      Promise.State.REJECTED -> {
+        child.setError((result as Throwable?)!!)
+        return
       }
     }
 
-    @Override
-    public void consume(T t) {
-      List<Consumer<? super T>> list;
-      synchronized (this) {
-        list = consumers;
-        consumers = null;
-      }
-
-      if (list != null) {
-        for (Consumer<? super T> consumer : list) {
-          if (!isObsolete(consumer)) {
-            consumer.consume(t);
-          }
-        }
-      }
-    }
-
-    public void add(@NotNull Consumer<? super T> consumer) {
-      synchronized (this) {
-        if (consumers != null) {
-          consumers.add(consumer);
-        }
-      }
-    }
+    addHandlers(Consumer({ child.catchError { child.setResult(it) } }), Consumer({ child.setError(it) }))
   }
 
-  @Override
-  @NotNull
-  public <SUB_RESULT> Promise<SUB_RESULT> then(@NotNull final Function<? super T, ? extends SUB_RESULT> fulfilled) {
-    switch (state) {
-      case PENDING:
-        break;
-      case FULFILLED:
-        //noinspection unchecked
-        return new DonePromise<SUB_RESULT>(fulfilled.fun((T)result));
-      case REJECTED:
-        return new RejectedPromise<SUB_RESULT>((Throwable)result);
+  override fun <SUB_RESULT> thenAsync(fulfilled: Function<in T, Promise<SUB_RESULT>>): Promise<SUB_RESULT> {
+    @Suppress("UNCHECKED_CAST")
+    when (state) {
+      Promise.State.PENDING -> {
+      }
+      Promise.State.FULFILLED -> return fulfilled.`fun`(result as T?)
+      Promise.State.REJECTED -> return rejectedPromise(result as Throwable)
     }
 
-    final AsyncPromise<SUB_RESULT> promise = new AsyncPromise<SUB_RESULT>();
-    addHandlers(result -> {
-      try {
-        if (fulfilled instanceof Obsolescent && ((Obsolescent)fulfilled).isObsolete()) {
-          promise.setError(OBSOLETE_ERROR);
-        }
-        else {
-          promise.setResult(fulfilled.fun(result));
-        }
-      }
-      catch (Throwable e) {
-        promise.setError(e);
-      }
-    }, promise::setError);
-    return promise;
+    val promise = AsyncPromise<SUB_RESULT>()
+    val rejectedHandler = Consumer<Throwable>({ promise.setError(it) })
+    addHandlers(Consumer({
+                           promise.catchError {
+                             fulfilled.`fun`(it)
+                                 .done { promise.catchError { promise.setResult(it) } }
+                                 .rejected(rejectedHandler)
+                           }
+                         }), rejectedHandler)
+    return promise
   }
 
-  @Override
-  public void notify(@NotNull final AsyncPromise<? super T> child) {
-    LOG.assertTrue(child != this);
-
-    switch (state) {
-      case PENDING:
-        break;
-      case FULFILLED:
-        //noinspection unchecked
-        child.setResult((T)result);
-        return;
-      case REJECTED:
-        child.setError((Throwable)result);
-        return;
+  override fun processed(fulfilled: AsyncPromise<in T>): Promise<T> {
+    when (state) {
+      Promise.State.PENDING -> {
+      }
+      Promise.State.FULFILLED -> {
+        @Suppress("UNCHECKED_CAST")
+        fulfilled.setResult(result as T)
+        return this
+      }
+      Promise.State.REJECTED -> {
+        fulfilled.setError((result as Throwable?)!!)
+        return this
+      }
     }
 
-    addHandlers(result -> {
-      try {
-        child.setResult(result);
-      }
-      catch (Throwable e) {
-        child.setError(e);
-      }
-    }, child::setError);
+    addHandlers(Consumer({ result -> fulfilled.catchError { fulfilled.setResult(result) } }), Consumer({ fulfilled.setError(it) }))
+    return this
   }
 
-  @Override
-  @NotNull
-  public <SUB_RESULT> Promise<SUB_RESULT> thenAsync(@NotNull final Function<? super T, Promise<SUB_RESULT>> fulfilled) {
-    switch (state) {
-      case PENDING:
-        break;
-      case FULFILLED:
-        //noinspection unchecked
-        return fulfilled.fun((T)result);
-      case REJECTED:
-        return Promise.reject((Throwable)result);
-    }
-
-    final AsyncPromise<SUB_RESULT> promise = new AsyncPromise<SUB_RESULT>();
-    final Consumer<Throwable> rejectedHandler = promise::setError;
-    addHandlers(result -> {
-      try {
-        fulfilled.fun(result)
-          .done(subResult -> {
-            try {
-              promise.setResult(subResult);
-            }
-            catch (Throwable e) {
-              promise.setError(e);
-            }
-          })
-          .rejected(rejectedHandler);
-      }
-      catch (Throwable e) {
-        promise.setError(e);
-      }
-    }, rejectedHandler);
-    return promise;
+  private fun addHandlers(done: Consumer<T>, rejected: Consumer<Throwable>) {
+    this.done = setHandler(this.done, done)
+    this.rejected = setHandler(this.rejected, rejected)
   }
 
-  @Override
-  @NotNull
-  public Promise<T> processed(@NotNull AsyncPromise<? super T> fulfilled) {
-    switch (state) {
-      case PENDING:
-        break;
-      case FULFILLED:
-        //noinspection unchecked
-        fulfilled.setResult((T)result);
-        return this;
-      case REJECTED:
-        fulfilled.setError((Throwable)result);
-        return this;
+  fun setResult(result: T?) {
+    if (state != Promise.State.PENDING) {
+      return
     }
 
-    addHandlers(result -> {
-      try {
-        fulfilled.setResult(result);
-      }
-      catch (Throwable e) {
-        fulfilled.setError(e);
-      }
-    }, fulfilled::setError);
-    return this;
-  }
+    this.result = result
+    state = Promise.State.FULFILLED
 
-  private void addHandlers(@NotNull Consumer<T> done, @NotNull Consumer<Throwable> rejected) {
-    this.done = setHandler(this.done, done);
-    this.rejected = setHandler(this.rejected, rejected);
-  }
-
-  @NotNull
-  private static <T> Consumer<? super T> setHandler(@Nullable Consumer<? super T> oldConsumer, @NotNull Consumer<? super T> newConsumer) {
-    if (oldConsumer == null) {
-      return newConsumer;
-    }
-    else if (oldConsumer instanceof CompoundConsumer) {
-      //noinspection unchecked
-      ((CompoundConsumer<T>)oldConsumer).add(newConsumer);
-      return oldConsumer;
-    }
-    else {
-      return new CompoundConsumer<T>(oldConsumer, newConsumer);
-    }
-  }
-
-  public void setResult(T result) {
-    if (state != State.PENDING) {
-      return;
-    }
-
-    this.result = result;
-    state = State.FULFILLED;
-
-    Consumer<? super T> done = this.done;
-    clearHandlers();
+    val done = this.done
+    clearHandlers()
     if (done != null && !isObsolete(done)) {
-      done.consume(result);
+      done.consume(result)
     }
   }
 
-  static boolean isObsolete(@Nullable Consumer<?> consumer) {
-    return consumer instanceof Obsolescent && ((Obsolescent)consumer).isObsolete();
+  fun setError(error: String): Boolean {
+    return setError(Promise.createError(error))
   }
 
-  public boolean setError(@NotNull String error) {
-    return setError(Promise.createError(error));
-  }
-
-  public boolean setError(@NotNull Throwable error) {
-    if (state != State.PENDING) {
-      return false;
+  open fun setError(error: Throwable): Boolean {
+    if (state != Promise.State.PENDING) {
+      return false
     }
 
-    result = error;
-    state = State.REJECTED;
+    result = error
+    state = Promise.State.REJECTED
 
-    Consumer<? super Throwable> rejected = this.rejected;
-    clearHandlers();
+    val rejected = this.rejected
+    clearHandlers()
     if (rejected == null) {
-      Promise.logError(LOG, error);
+      Promise.logError(LOG, error)
     }
     else if (!isObsolete(rejected)) {
-      rejected.consume(error);
+      rejected.consume(error)
     }
-    return true;
+    return true
   }
 
-  private void clearHandlers() {
-    done = null;
-    rejected = null;
+  private fun clearHandlers() {
+    done = null
+    rejected = null
   }
 
-  @Override
-  public Promise<T> processed(@NotNull Consumer<? super T> processed) {
-    done(processed);
-    rejected(error -> processed.consume(null));
-    return this;
+  override fun processed(processed: Consumer<in T>): Promise<T> {
+    done(processed)
+    rejected({ error -> processed.consume(null) })
+    return this
   }
-}
\ No newline at end of file
+}
+
+private class CompoundConsumer<T>(c1: Consumer<in T>, c2: Consumer<in T>) : Consumer<T> {
+  private var consumers: MutableList<Consumer<in T>>? = ArrayList()
+
+  init {
+    synchronized(this) {
+      consumers!!.add(c1)
+      consumers!!.add(c2)
+    }
+  }
+
+  override fun consume(t: T) {
+    val list = synchronized(this) {
+      val list = consumers
+      consumers = null
+      list
+    } ?: return
+
+    for (consumer in list) {
+      if (!isObsolete(consumer)) {
+        consumer.consume(t)
+      }
+    }
+  }
+
+  fun add(consumer: Consumer<in T>) {
+    synchronized(this) {
+      if (consumers != null) {
+        consumers!!.add(consumer)
+      }
+    }
+  }
+}
+
+private fun <T> setHandler(oldConsumer: Consumer<in T>?, newConsumer: Consumer<in T>) = when (oldConsumer) {
+  null -> newConsumer
+  is CompoundConsumer<*> -> {
+    @Suppress("UNCHECKED_CAST")
+    (oldConsumer as CompoundConsumer<T>).add(newConsumer)
+    oldConsumer
+  }
+  else -> CompoundConsumer(oldConsumer, newConsumer)
+}
+
+internal fun isObsolete(consumer: Consumer<*>?) = consumer is Obsolescent && consumer.isObsolete
+
+inline fun <T> AsyncPromise<*>.catchError(runnable: () -> T): T? {
+  try {
+    return runnable()
+  }
+  catch (e: Throwable) {
+    setError(e)
+    return null
+  }
+}
+
+fun <T> rejectedPromise(error: Throwable): Promise<T> = Promise.reject(error)
\ No newline at end of file
diff --git a/platform/script-debugger/debugger-ui/src/org/jetbrains/debugger/RejectErrorReporter.java b/platform/script-debugger/debugger-ui/src/org/jetbrains/debugger/RejectErrorReporter.java
index 337ec586106e..604718a562e6 100644
--- a/platform/script-debugger/debugger-ui/src/org/jetbrains/debugger/RejectErrorReporter.java
+++ b/platform/script-debugger/debugger-ui/src/org/jetbrains/debugger/RejectErrorReporter.java
@@ -13,34 +13,19 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.jetbrains.debugger;
+package org.jetbrains.debugger
 
-import com.intellij.util.Consumer;
-import com.intellij.xdebugger.XDebugSession;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-import org.jetbrains.concurrency.AsyncPromise;
-import org.jetbrains.concurrency.Promise;
-import org.jetbrains.rpc.CommandProcessorKt;
+import com.intellij.util.Consumer
+import com.intellij.xdebugger.XDebugSession
+import org.jetbrains.concurrency.OBSOLETE_ERROR
+import org.jetbrains.concurrency.Promise
+import org.jetbrains.rpc.LOG
 
-public final class RejectErrorReporter implements Consumer<Throwable> {
-  private final XDebugSession session;
-  private final String description;
-
-  public RejectErrorReporter(@NotNull XDebugSession session) {
-    this(session, null);
-  }
-
-  public RejectErrorReporter(@NotNull XDebugSession session, @Nullable String description) {
-    this.session = session;
-    this.description = description;
-  }
-
-  @Override
-  public void consume(Throwable error) {
-    Promise.logError(CommandProcessorKt.getLOG(), error);
-    if (error != AsyncPromise.OBSOLETE_ERROR) {
-      session.reportError((description == null ? "" : description + ": ") + error.getMessage());
+class RejectErrorReporter @JvmOverloads constructor(private val session: XDebugSession, private val description: String? = null) : Consumer<Throwable> {
+  override fun consume(error: Throwable) {
+    Promise.logError(LOG, error)
+    if (error !== OBSOLETE_ERROR) {
+      session.reportError((if (description == null) "" else "$description: ") + error.message)
     }
   }
 }
\ No newline at end of file