diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
index 9f74daec6c0..c7dbfe16068 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
@@ -23,11 +23,11 @@ import com.intellij.psi.PsiElement;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.PsiTreeUtil;
 import kotlin.Function1;
+import kotlin.Function3;
 import kotlin.Unit;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.cfg.pseudocodeTraverser.Edges;
-import org.jetbrains.jet.lang.cfg.pseudocodeTraverser.InstructionDataAnalyzeStrategy;
 import org.jetbrains.jet.lang.cfg.pseudocodeTraverser.PseudocodeTraverserPackage;
 import org.jetbrains.jet.lang.cfg.PseudocodeVariablesData.VariableInitState;
 import org.jetbrains.jet.lang.cfg.PseudocodeVariablesData.VariableUseState;
@@ -267,7 +267,7 @@ public class JetFlowInformationProvider {
 
         PseudocodeTraverserPackage.traverse(
                 pseudocode, FORWARD, initializers,
-                new InstructionDataAnalyzeStrategyJ<Map<VariableDescriptor, PseudocodeVariablesData.VariableInitState>>() {
+                new InstructionDataAnalyzeStrategy<Map<VariableDescriptor, VariableInitState>>() {
             @Override
             public void execute(@NotNull Instruction instruction,
                     @Nullable Map<VariableDescriptor, VariableInitState> in,
@@ -517,7 +517,7 @@ public class JetFlowInformationProvider {
         Map<Instruction, Edges<Map<VariableDescriptor, VariableUseState>>> variableStatusData = pseudocodeVariablesData.getVariableUseStatusData();
         final Map<Instruction, DiagnosticFactory> reportedDiagnosticMap = Maps.newHashMap();
         InstructionDataAnalyzeStrategy<Map<VariableDescriptor, VariableUseState>> variableStatusAnalyzeStrategy =
-                new InstructionDataAnalyzeStrategyJ<Map<VariableDescriptor, PseudocodeVariablesData.VariableUseState>>() {
+                new InstructionDataAnalyzeStrategy<Map<VariableDescriptor, VariableUseState>>() {
             @Override
             public void execute(@NotNull Instruction instruction,
                     @Nullable Map<VariableDescriptor, VariableUseState> in,
@@ -885,7 +885,7 @@ public class JetFlowInformationProvider {
     }
 
     //TODO after KT-4621 rewrite to Kotlin
-    public abstract static class InstructionDataAnalyzeStrategyJ<D> implements InstructionDataAnalyzeStrategy<D> {
+    public abstract static class InstructionDataAnalyzeStrategy<D> implements Function3<Instruction, D, D, Unit> {
         @Override
         public Unit invoke(Instruction instruction, D enterData, D exitData) {
             execute(instruction, enterData, exitData);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeTraverser.kt b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeTraverser.kt
index 35b5e538cae..9de52f89901 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeTraverser.kt
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeTraverser.kt
@@ -60,16 +60,16 @@ fun Pseudocode.traverse(
 fun <D> Pseudocode.traverse(
         traversalOrder: TraversalOrder,
         edgesMap: Map<Instruction, Edges<D>>,
-        instructionDataAnalyzeStrategy: InstructionDataAnalyzeStrategy<D>
+        analyzeInstruction: (Instruction, D, D) -> Unit
 ) {
     val instructions = getInstructions(traversalOrder)
     for (instruction in instructions) {
         if (instruction is LocalFunctionDeclarationInstruction) {
-            instruction.getBody().traverse(traversalOrder, edgesMap, instructionDataAnalyzeStrategy)
+            instruction.getBody().traverse(traversalOrder, edgesMap, analyzeInstruction)
         }
         val edges = edgesMap.get(instruction)
         if (edges != null) {
-            instructionDataAnalyzeStrategy(instruction, edges.`in`, edges.out)
+            analyzeInstruction(instruction, edges.`in`, edges.out)
         }
     }
 }
@@ -185,9 +185,6 @@ private fun <D> Pseudocode.collectDataFromSubgraph(
     }
 }
 
-trait InstructionDataMergeStrategy<D> : (Instruction, Collection<D>) -> Edges<D>
-trait InstructionDataAnalyzeStrategy<D> : (Instruction, D, D) -> Unit
-
 data class Edges<T>(val `in`: T, val out: T)
 fun <T> createEdges(`in`: T, out: T) = Edges(`in`, out)
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeVariableDataCollector.kt b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeVariableDataCollector.kt
index 1e5e8b379e4..232c71e6da5 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeVariableDataCollector.kt
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeVariableDataCollector.kt
@@ -41,11 +41,13 @@ public class PseudocodeVariableDataCollector(
     public fun <D> collectData(
             traversalOrder: TraversalOrder,
             mergeDataWithLocalDeclarations: Boolean,
-            instructionDataMergeStrategy: InstructionDataMergeStrategy<MutableMap<VariableDescriptor, D>>
+            instructionDataMergeStrategy: InstructionDataMergeStrategy<D>
     ): MutableMap<Instruction, Edges<MutableMap<VariableDescriptor, D>>> {
         val result = pseudocode.collectData(
                 traversalOrder, mergeDataWithLocalDeclarations,
-                instructionDataMergeStrategy as InstructionDataMergeStrategy<Map<VariableDescriptor, D>>,
+                //see KT-4605
+                instructionDataMergeStrategy as
+                    (Instruction, Collection<Map<VariableDescriptor, D>>) -> Edges<Map<VariableDescriptor, D>>,
                 { (from, to, data) -> filterOutVariablesOutOfScope(from, to, data)},
                 Collections.emptyMap<VariableDescriptor, D>())
         //see KT-4605
@@ -88,6 +90,10 @@ public class PseudocodeVariableDataCollector(
     }
 }
 
+//todo may be a type alias
+trait InstructionDataMergeStrategy<D> :
+  (Instruction, Collection<MutableMap<VariableDescriptor, D>>) -> Edges<MutableMap<VariableDescriptor, D>>
+
 public trait LexicalScopeVariableInfo {
     val declaredIn : Map<VariableDescriptor, LexicalScope>
     val scopeVariables : Map<LexicalScope, Collection<VariableDescriptor>>
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeVariablesData.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeVariablesData.java
index aed54128222..728c65aab00 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeVariablesData.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/PseudocodeVariablesData.java
@@ -23,7 +23,6 @@ import kotlin.Unit;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.cfg.pseudocodeTraverser.Edges;
-import org.jetbrains.jet.lang.cfg.pseudocodeTraverser.InstructionDataMergeStrategy;
 import org.jetbrains.jet.lang.cfg.pseudocodeTraverser.PseudocodeTraverserPackage;
 import org.jetbrains.jet.lang.cfg.pseudocode.*;
 import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
@@ -148,7 +147,7 @@ public class PseudocodeVariablesData {
 
         return pseudocodeVariableDataCollector.collectData(
                 FORWARD, /*mergeDataWithLocalDeclarations=*/ false,
-                new InstructionDataMergeStrategy<Map<VariableDescriptor, VariableInitState>>() {
+                new InstructionDataMergeStrategy<VariableInitState>() {
                     @NotNull
                     @Override
                     public Edges<Map<VariableDescriptor, VariableInitState>> invoke(
@@ -248,7 +247,7 @@ public class PseudocodeVariablesData {
     public Map<Instruction, Edges<Map<VariableDescriptor, VariableUseState>>> getVariableUseStatusData() {
         return pseudocodeVariableDataCollector.collectData(
                 BACKWARD, /*mergeDataWithLocalDeclarations=*/ true,
-                new InstructionDataMergeStrategy<Map<VariableDescriptor, VariableUseState>>() {
+                new InstructionDataMergeStrategy<VariableUseState>() {
                     @NotNull
                     @Override
                     public Edges<Map<VariableDescriptor, VariableUseState>> invoke(