diff --git a/compiler/frontend/src/jet/ExtensionFunctions.jet b/compiler/frontend/src/jet/ExtensionFunctions.jet
index 580f3358e71..edd95b75e86 100644
--- a/compiler/frontend/src/jet/ExtensionFunctions.jet
+++ b/compiler/frontend/src/jet/ExtensionFunctions.jet
@@ -2,72 +2,72 @@
 
 package jet
 
-public abstract class ExtensionFunction0<in T, out R> {
-  public abstract fun T.invoke() : R
+public trait ExtensionFunction0<in T, out R> {
+    public fun T.invoke() : R
 }
-public abstract class ExtensionFunction1<in T, in P1, out R> {
-  public abstract fun T.invoke(p1: P1) : R
+public trait ExtensionFunction1<in T, in P1, out R> {
+    public fun T.invoke(p1: P1) : R
 }
-public abstract class ExtensionFunction2<in T, in P1, in P2, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2) : R
+public trait ExtensionFunction2<in T, in P1, in P2, out R> {
+    public fun T.invoke(p1: P1, p2: P2) : R
 }
-public abstract class ExtensionFunction3<in T, in P1, in P2, in P3, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3) : R
+public trait ExtensionFunction3<in T, in P1, in P2, in P3, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3) : R
 }
-public abstract class ExtensionFunction4<in T, in P1, in P2, in P3, in P4, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4) : R
+public trait ExtensionFunction4<in T, in P1, in P2, in P3, in P4, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4) : R
 }
-public abstract class ExtensionFunction5<in T, in P1, in P2, in P3, in P4, in P5, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5) : R
+public trait ExtensionFunction5<in T, in P1, in P2, in P3, in P4, in P5, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5) : R
 }
-public abstract class ExtensionFunction6<in T, in P1, in P2, in P3, in P4, in P5, in P6, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6) : R
+public trait ExtensionFunction6<in T, in P1, in P2, in P3, in P4, in P5, in P6, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6) : R
 }
-public abstract class ExtensionFunction7<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7) : R
+public trait ExtensionFunction7<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7) : R
 }
-public abstract class ExtensionFunction8<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8) : R
+public trait ExtensionFunction8<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8) : R
 }
-public abstract class ExtensionFunction9<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9) : R
+public trait ExtensionFunction9<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9) : R
 }
-public abstract class ExtensionFunction10<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10) : R
+public trait ExtensionFunction10<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10) : R
 }
-public abstract class ExtensionFunction11<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11) : R
+public trait ExtensionFunction11<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11) : R
 }
-public abstract class ExtensionFunction12<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12) : R
+public trait ExtensionFunction12<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12) : R
 }
-public abstract class ExtensionFunction13<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13) : R
+public trait ExtensionFunction13<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13) : R
 }
-public abstract class ExtensionFunction14<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14) : R
+public trait ExtensionFunction14<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14) : R
 }
-public abstract class ExtensionFunction15<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15) : R
+public trait ExtensionFunction15<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15) : R
 }
-public abstract class ExtensionFunction16<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16) : R
+public trait ExtensionFunction16<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16) : R
 }
-public abstract class ExtensionFunction17<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17) : R
+public trait ExtensionFunction17<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17) : R
 }
-public abstract class ExtensionFunction18<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18) : R
+public trait ExtensionFunction18<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18) : R
 }
-public abstract class ExtensionFunction19<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19) : R
+public trait ExtensionFunction19<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19) : R
 }
-public abstract class ExtensionFunction20<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20) : R
+public trait ExtensionFunction20<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20) : R
 }
-public abstract class ExtensionFunction21<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, in P21, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20, p21: P21) : R
+public trait ExtensionFunction21<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, in P21, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20, p21: P21) : R
 }
-public abstract class ExtensionFunction22<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, in P21, in P22, out R> {
-  public abstract fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20, p21: P21, p22: P22) : R
+public trait ExtensionFunction22<in T, in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, in P21, in P22, out R> {
+    public fun T.invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20, p21: P21, p22: P22) : R
 }
diff --git a/compiler/frontend/src/jet/Functions.jet b/compiler/frontend/src/jet/Functions.jet
index 727a60f3fea..0ac68dd2251 100644
--- a/compiler/frontend/src/jet/Functions.jet
+++ b/compiler/frontend/src/jet/Functions.jet
@@ -2,72 +2,72 @@
 
 package jet
 
-public abstract class Function0<out R> {
-  public abstract fun invoke() : R
+public trait Function0<out R> {
+    public fun invoke() : R
 }
-public abstract class Function1<in P1, out R> {
-  public abstract fun invoke(p1: P1) : R
+public trait Function1<in P1, out R> {
+    public fun invoke(p1: P1) : R
 }
-public abstract class Function2<in P1, in P2, out R> {
-  public abstract fun invoke(p1: P1, p2: P2) : R
+public trait Function2<in P1, in P2, out R> {
+    public fun invoke(p1: P1, p2: P2) : R
 }
-public abstract class Function3<in P1, in P2, in P3, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3) : R
+public trait Function3<in P1, in P2, in P3, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3) : R
 }
-public abstract class Function4<in P1, in P2, in P3, in P4, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4) : R
+public trait Function4<in P1, in P2, in P3, in P4, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4) : R
 }
-public abstract class Function5<in P1, in P2, in P3, in P4, in P5, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5) : R
+public trait Function5<in P1, in P2, in P3, in P4, in P5, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5) : R
 }
-public abstract class Function6<in P1, in P2, in P3, in P4, in P5, in P6, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6) : R
+public trait Function6<in P1, in P2, in P3, in P4, in P5, in P6, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6) : R
 }
-public abstract class Function7<in P1, in P2, in P3, in P4, in P5, in P6, in P7, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7) : R
+public trait Function7<in P1, in P2, in P3, in P4, in P5, in P6, in P7, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7) : R
 }
-public abstract class Function8<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8) : R
+public trait Function8<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8) : R
 }
-public abstract class Function9<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9) : R
+public trait Function9<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9) : R
 }
-public abstract class Function10<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10) : R
+public trait Function10<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10) : R
 }
-public abstract class Function11<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11) : R
+public trait Function11<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11) : R
 }
-public abstract class Function12<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12) : R
+public trait Function12<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12) : R
 }
-public abstract class Function13<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13) : R
+public trait Function13<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13) : R
 }
-public abstract class Function14<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14) : R
+public trait Function14<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14) : R
 }
-public abstract class Function15<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15) : R
+public trait Function15<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15) : R
 }
-public abstract class Function16<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16) : R
+public trait Function16<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16) : R
 }
-public abstract class Function17<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17) : R
+public trait Function17<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17) : R
 }
-public abstract class Function18<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18) : R
+public trait Function18<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18) : R
 }
-public abstract class Function19<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19) : R
+public trait Function19<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19) : R
 }
-public abstract class Function20<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20) : R
+public trait Function20<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20) : R
 }
-public abstract class Function21<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, in P21, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20, p21: P21) : R
+public trait Function21<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, in P21, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20, p21: P21) : R
 }
-public abstract class Function22<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, in P21, in P22, out R> {
-  public abstract fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20, p21: P21, p22: P22) : R
+public trait Function22<in P1, in P2, in P3, in P4, in P5, in P6, in P7, in P8, in P9, in P10, in P11, in P12, in P13, in P14, in P15, in P16, in P17, in P18, in P19, in P20, in P21, in P22, out R> {
+    public fun invoke(p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, p10: P10, p11: P11, p12: P12, p13: P13, p14: P14, p15: P15, p16: P16, p17: P17, p18: P18, p19: P19, p20: P20, p21: P21, p22: P22) : R
 }
diff --git a/compiler/testData/builtin-classes.txt b/compiler/testData/builtin-classes.txt
index 3621e23a323..8684c33fec2 100644
--- a/compiler/testData/builtin-classes.txt
+++ b/compiler/testData/builtin-classes.txt
@@ -378,118 +378,95 @@ public abstract class Enum</*0*/ E : jet.Enum<E>> {
     public final fun ordinal() : jet.Int
 }
 
-public abstract class ExtensionFunction0</*0*/ in T, /*1*/ out R> {
-    public constructor ExtensionFunction0</*0*/ in T, /*1*/ out R>()
+public trait ExtensionFunction0</*0*/ in T, /*1*/ out R> {
     public abstract fun T.invoke() : R
 }
 
-public abstract class ExtensionFunction1</*0*/ in T, /*1*/ in P1, /*2*/ out R> {
-    public constructor ExtensionFunction1</*0*/ in T, /*1*/ in P1, /*2*/ out R>()
+public trait ExtensionFunction1</*0*/ in T, /*1*/ in P1, /*2*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1) : R
 }
 
-public abstract class ExtensionFunction10</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ out R> {
-    public constructor ExtensionFunction10</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ out R>()
+public trait ExtensionFunction10</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10) : R
 }
 
-public abstract class ExtensionFunction11</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ out R> {
-    public constructor ExtensionFunction11</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ out R>()
+public trait ExtensionFunction11</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11) : R
 }
 
-public abstract class ExtensionFunction12</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ out R> {
-    public constructor ExtensionFunction12</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ out R>()
+public trait ExtensionFunction12</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12) : R
 }
 
-public abstract class ExtensionFunction13</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ out R> {
-    public constructor ExtensionFunction13</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ out R>()
+public trait ExtensionFunction13</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13) : R
 }
 
-public abstract class ExtensionFunction14</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ out R> {
-    public constructor ExtensionFunction14</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ out R>()
+public trait ExtensionFunction14</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14) : R
 }
 
-public abstract class ExtensionFunction15</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ out R> {
-    public constructor ExtensionFunction15</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ out R>()
+public trait ExtensionFunction15</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15) : R
 }
 
-public abstract class ExtensionFunction16</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ out R> {
-    public constructor ExtensionFunction16</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ out R>()
+public trait ExtensionFunction16</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16) : R
 }
 
-public abstract class ExtensionFunction17</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ out R> {
-    public constructor ExtensionFunction17</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ out R>()
+public trait ExtensionFunction17</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17) : R
 }
 
-public abstract class ExtensionFunction18</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ out R> {
-    public constructor ExtensionFunction18</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ out R>()
+public trait ExtensionFunction18</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17, /*17*/ p18 : P18) : R
 }
 
-public abstract class ExtensionFunction19</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ out R> {
-    public constructor ExtensionFunction19</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ out R>()
+public trait ExtensionFunction19</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17, /*17*/ p18 : P18, /*18*/ p19 : P19) : R
 }
 
-public abstract class ExtensionFunction2</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ out R> {
-    public constructor ExtensionFunction2</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ out R>()
+public trait ExtensionFunction2</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2) : R
 }
 
-public abstract class ExtensionFunction20</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ out R> {
-    public constructor ExtensionFunction20</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ out R>()
+public trait ExtensionFunction20</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17, /*17*/ p18 : P18, /*18*/ p19 : P19, /*19*/ p20 : P20) : R
 }
 
-public abstract class ExtensionFunction21</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ in P21, /*22*/ out R> {
-    public constructor ExtensionFunction21</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ in P21, /*22*/ out R>()
+public trait ExtensionFunction21</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ in P21, /*22*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17, /*17*/ p18 : P18, /*18*/ p19 : P19, /*19*/ p20 : P20, /*20*/ p21 : P21) : R
 }
 
-public abstract class ExtensionFunction22</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ in P21, /*22*/ in P22, /*23*/ out R> {
-    public constructor ExtensionFunction22</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ in P21, /*22*/ in P22, /*23*/ out R>()
+public trait ExtensionFunction22</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ in P10, /*11*/ in P11, /*12*/ in P12, /*13*/ in P13, /*14*/ in P14, /*15*/ in P15, /*16*/ in P16, /*17*/ in P17, /*18*/ in P18, /*19*/ in P19, /*20*/ in P20, /*21*/ in P21, /*22*/ in P22, /*23*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17, /*17*/ p18 : P18, /*18*/ p19 : P19, /*19*/ p20 : P20, /*20*/ p21 : P21, /*21*/ p22 : P22) : R
 }
 
-public abstract class ExtensionFunction3</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ out R> {
-    public constructor ExtensionFunction3</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ out R>()
+public trait ExtensionFunction3</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3) : R
 }
 
-public abstract class ExtensionFunction4</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ out R> {
-    public constructor ExtensionFunction4</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ out R>()
+public trait ExtensionFunction4</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4) : R
 }
 
-public abstract class ExtensionFunction5</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ out R> {
-    public constructor ExtensionFunction5</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ out R>()
+public trait ExtensionFunction5</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5) : R
 }
 
-public abstract class ExtensionFunction6</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ out R> {
-    public constructor ExtensionFunction6</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ out R>()
+public trait ExtensionFunction6</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6) : R
 }
 
-public abstract class ExtensionFunction7</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ out R> {
-    public constructor ExtensionFunction7</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ out R>()
+public trait ExtensionFunction7</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7) : R
 }
 
-public abstract class ExtensionFunction8</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ out R> {
-    public constructor ExtensionFunction8</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ out R>()
+public trait ExtensionFunction8</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8) : R
 }
 
-public abstract class ExtensionFunction9</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ out R> {
-    public constructor ExtensionFunction9</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ out R>()
+public trait ExtensionFunction9</*0*/ in T, /*1*/ in P1, /*2*/ in P2, /*3*/ in P3, /*4*/ in P4, /*5*/ in P5, /*6*/ in P6, /*7*/ in P7, /*8*/ in P8, /*9*/ in P9, /*10*/ out R> {
     public abstract fun T.invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9) : R
 }
 
@@ -597,118 +574,95 @@ public final class FloatRange : jet.Range<jet.Float>, jet.Progression<jet.Float>
     }
 }
 
-public abstract class Function0</*0*/ out R> {
-    public constructor Function0</*0*/ out R>()
+public trait Function0</*0*/ out R> {
     public abstract fun invoke() : R
 }
 
-public abstract class Function1</*0*/ in P1, /*1*/ out R> {
-    public constructor Function1</*0*/ in P1, /*1*/ out R>()
+public trait Function1</*0*/ in P1, /*1*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1) : R
 }
 
-public abstract class Function10</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ out R> {
-    public constructor Function10</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ out R>()
+public trait Function10</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10) : R
 }
 
-public abstract class Function11</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ out R> {
-    public constructor Function11</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ out R>()
+public trait Function11</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11) : R
 }
 
-public abstract class Function12</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ out R> {
-    public constructor Function12</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ out R>()
+public trait Function12</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12) : R
 }
 
-public abstract class Function13</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ out R> {
-    public constructor Function13</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ out R>()
+public trait Function13</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13) : R
 }
 
-public abstract class Function14</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ out R> {
-    public constructor Function14</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ out R>()
+public trait Function14</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14) : R
 }
 
-public abstract class Function15</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ out R> {
-    public constructor Function15</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ out R>()
+public trait Function15</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15) : R
 }
 
-public abstract class Function16</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ out R> {
-    public constructor Function16</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ out R>()
+public trait Function16</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16) : R
 }
 
-public abstract class Function17</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ out R> {
-    public constructor Function17</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ out R>()
+public trait Function17</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17) : R
 }
 
-public abstract class Function18</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ out R> {
-    public constructor Function18</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ out R>()
+public trait Function18</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17, /*17*/ p18 : P18) : R
 }
 
-public abstract class Function19</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ out R> {
-    public constructor Function19</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ out R>()
+public trait Function19</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17, /*17*/ p18 : P18, /*18*/ p19 : P19) : R
 }
 
-public abstract class Function2</*0*/ in P1, /*1*/ in P2, /*2*/ out R> {
-    public constructor Function2</*0*/ in P1, /*1*/ in P2, /*2*/ out R>()
+public trait Function2</*0*/ in P1, /*1*/ in P2, /*2*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2) : R
 }
 
-public abstract class Function20</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ in P20, /*20*/ out R> {
-    public constructor Function20</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ in P20, /*20*/ out R>()
+public trait Function20</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ in P20, /*20*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17, /*17*/ p18 : P18, /*18*/ p19 : P19, /*19*/ p20 : P20) : R
 }
 
-public abstract class Function21</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ in P20, /*20*/ in P21, /*21*/ out R> {
-    public constructor Function21</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ in P20, /*20*/ in P21, /*21*/ out R>()
+public trait Function21</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ in P20, /*20*/ in P21, /*21*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17, /*17*/ p18 : P18, /*18*/ p19 : P19, /*19*/ p20 : P20, /*20*/ p21 : P21) : R
 }
 
-public abstract class Function22</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ in P20, /*20*/ in P21, /*21*/ in P22, /*22*/ out R> {
-    public constructor Function22</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ in P20, /*20*/ in P21, /*21*/ in P22, /*22*/ out R>()
+public trait Function22</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ in P10, /*10*/ in P11, /*11*/ in P12, /*12*/ in P13, /*13*/ in P14, /*14*/ in P15, /*15*/ in P16, /*16*/ in P17, /*17*/ in P18, /*18*/ in P19, /*19*/ in P20, /*20*/ in P21, /*21*/ in P22, /*22*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9, /*9*/ p10 : P10, /*10*/ p11 : P11, /*11*/ p12 : P12, /*12*/ p13 : P13, /*13*/ p14 : P14, /*14*/ p15 : P15, /*15*/ p16 : P16, /*16*/ p17 : P17, /*17*/ p18 : P18, /*18*/ p19 : P19, /*19*/ p20 : P20, /*20*/ p21 : P21, /*21*/ p22 : P22) : R
 }
 
-public abstract class Function3</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ out R> {
-    public constructor Function3</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ out R>()
+public trait Function3</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3) : R
 }
 
-public abstract class Function4</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ out R> {
-    public constructor Function4</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ out R>()
+public trait Function4</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4) : R
 }
 
-public abstract class Function5</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ out R> {
-    public constructor Function5</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ out R>()
+public trait Function5</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5) : R
 }
 
-public abstract class Function6</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ out R> {
-    public constructor Function6</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ out R>()
+public trait Function6</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6) : R
 }
 
-public abstract class Function7</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ out R> {
-    public constructor Function7</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ out R>()
+public trait Function7</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7) : R
 }
 
-public abstract class Function8</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ out R> {
-    public constructor Function8</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ out R>()
+public trait Function8</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8) : R
 }
 
-public abstract class Function9</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ out R> {
-    public constructor Function9</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ out R>()
+public trait Function9</*0*/ in P1, /*1*/ in P2, /*2*/ in P3, /*3*/ in P4, /*4*/ in P5, /*5*/ in P6, /*6*/ in P7, /*7*/ in P8, /*8*/ in P9, /*9*/ out R> {
     public abstract fun invoke(/*0*/ p1 : P1, /*1*/ p2 : P2, /*2*/ p3 : P3, /*3*/ p4 : P4, /*4*/ p5 : P5, /*5*/ p6 : P6, /*6*/ p7 : P7, /*7*/ p8 : P8, /*8*/ p9 : P9) : R
 }
 
diff --git a/compiler/testData/diagnostics/tests/override/ExtendFunctionClass.kt b/compiler/testData/diagnostics/tests/override/ExtendFunctionClass.kt
index bfbc3238d3b..a86867d8b90 100644
--- a/compiler/testData/diagnostics/tests/override/ExtendFunctionClass.kt
+++ b/compiler/testData/diagnostics/tests/override/ExtendFunctionClass.kt
@@ -1,9 +1,9 @@
 package extendFunctionClass
 
-class <!ABSTRACT_MEMBER_NOT_IMPLEMENTED!>A<!> : Function1<Int, Int>() {
+class <!ABSTRACT_MEMBER_NOT_IMPLEMENTED!>A<!> : Function1<Int, Int> {
 
 }
 
-class B : Function1<Int, Int>() {
+class B : Function1<Int, Int> {
     override fun invoke(p1 : Int) = p1
 }
diff --git a/generators/org/jetbrains/jet/generators/runtime/GenerateFunctions.java b/generators/org/jetbrains/jet/generators/runtime/GenerateFunctions.java
index a27b14b1cfa..9cea5e8efa4 100644
--- a/generators/org/jetbrains/jet/generators/runtime/GenerateFunctions.java
+++ b/generators/org/jetbrains/jet/generators/runtime/GenerateFunctions.java
@@ -18,7 +18,6 @@ package org.jetbrains.jet.generators.runtime;
 
 import com.intellij.openapi.util.io.FileUtil;
 import org.jetbrains.jet.utils.ExceptionUtils;
-import org.jetbrains.jet.utils.Printer;
 
 import java.io.File;
 import java.io.FileNotFoundException;
@@ -41,12 +40,20 @@ public class GenerateFunctions {
             this.classNamePrefix = classNamePrefix;
             this.hasReceiverParameter = hasReceiverParameter;
         }
+
+        public String getClassName(int i) {
+            return classNamePrefix + i;
+        }
+
+        public String getImplClassName(int i) {
+            return classNamePrefix + "Impl" + i;
+        }
     }
 
     private static void generateBuiltInFunctions(PrintStream out, int count, FunctionKind kind) {
         generated(out);
         for (int i = 0; i <= count; i++) {
-            out.print("public abstract class " + kind.classNamePrefix + i);
+            out.print("public trait " + kind.getClassName(i));
             out.print("<");
             if (kind.hasReceiverParameter) {
                 out.print("in T, ");
@@ -56,7 +63,7 @@ public class GenerateFunctions {
             }
             out.print("out R> {");
             out.println();
-            out.print("  public abstract fun " + (kind.hasReceiverParameter ? "T." : "") + "invoke(");
+            out.print("    public fun " + (kind.hasReceiverParameter ? "T." : "") + "invoke(");
             for (int j = 1; j <= i; j++) {
                 out.print("p" + j + ": " + "P" + j);
                 if (j < i) {
@@ -72,17 +79,14 @@ public class GenerateFunctions {
     private static void generateRuntimeFunction(PrintStream out, int i, FunctionKind kind) {
         generateRuntimeClassHeader(out);
 
-        out.print("public abstract class " + kind.classNamePrefix + i);
-        out.print("<");
-        if (kind.hasReceiverParameter) {
-            out.print("T, ");
-        }
-        for (int j = 1; j <= i; j++) {
-            out.print("P" + j + ", ");
-        }
-        out.print("R> extends DefaultJetObject {");
+        out.println("import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;");
         out.println();
-        out.print("    public abstract R invoke(");
+        out.println("@AssertInvisibleInResolver");
+
+        out.print("public interface " + kind.getClassName(i));
+        generateTypeParameters(out, i, kind);
+        out.println(" {");
+        out.print("    R invoke(");
         if (kind.hasReceiverParameter) {
             out.print("T receiver");
             if (i > 0) {
@@ -95,8 +99,31 @@ public class GenerateFunctions {
                 out.print(", ");
             }
         }
-        out.print(");");
-        out.println();
+        out.println(");");
+        out.println("}");
+    }
+
+    private static void generateTypeParameters(PrintStream out, int i, FunctionKind kind) {
+        out.print("<");
+        if (kind.hasReceiverParameter) {
+            out.print("T, ");
+        }
+        for (int j = 1; j <= i; j++) {
+            out.print("P" + j + ", ");
+        }
+        out.print("R>");
+    }
+
+    private static void generateRuntimeFunctionImpl(PrintStream out, int i, FunctionKind kind) {
+        generateRuntimeClassHeader(out);
+
+        out.print("public abstract class " + kind.getImplClassName(i));
+        generateTypeParameters(out, i, kind);
+        out.print(" extends DefaultJetObject");
+        out.print(" implements " + kind.getClassName(i));
+        generateTypeParameters(out, i, kind);
+        out.println(" {");
+        // TODO: toString()
         out.println("}");
     }
 
@@ -109,9 +136,6 @@ public class GenerateFunctions {
         }
         out.println("package jet;");
         out.println();
-        out.println("import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;");
-        out.println();
-        out.println("@AssertInvisibleInResolver");
     }
 
     private static void generated(PrintStream out) {
@@ -138,9 +162,13 @@ public class GenerateFunctions {
 
         for (FunctionKind kind : FunctionKind.values()) {
             for (int i = 0; i <= MAX_PARAM_COUNT; i++) {
-                PrintStream function = new PrintStream(new File(baseDir, kind.classNamePrefix + i + ".java"));
+                PrintStream function = new PrintStream(new File(baseDir, kind.getClassName(i) + ".java"));
                 generateRuntimeFunction(function, i, kind);
                 function.close();
+
+                PrintStream functionImpl = new PrintStream(new File(baseDir, kind.getImplClassName(i) + ".java"));
+                generateRuntimeFunctionImpl(functionImpl, i, kind);
+                functionImpl.close();
             }
         }
     }
diff --git a/runtime/src/jet/ExtensionFunction0.java b/runtime/src/jet/ExtensionFunction0.java
index 8adb43ca82e..6d459301d73 100644
--- a/runtime/src/jet/ExtensionFunction0.java
+++ b/runtime/src/jet/ExtensionFunction0.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction0<T, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver);
+public interface ExtensionFunction0<T, R> {
+    R invoke(T receiver);
 }
diff --git a/runtime/src/jet/ExtensionFunction1.java b/runtime/src/jet/ExtensionFunction1.java
index 52a063cf7b6..1be47c601d9 100644
--- a/runtime/src/jet/ExtensionFunction1.java
+++ b/runtime/src/jet/ExtensionFunction1.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction1<T, P1, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1);
+public interface ExtensionFunction1<T, P1, R> {
+    R invoke(T receiver, P1 p1);
 }
diff --git a/runtime/src/jet/ExtensionFunction10.java b/runtime/src/jet/ExtensionFunction10.java
index d91bcef211c..ce43c9456ad 100644
--- a/runtime/src/jet/ExtensionFunction10.java
+++ b/runtime/src/jet/ExtensionFunction10.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction10<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10);
+public interface ExtensionFunction10<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10);
 }
diff --git a/runtime/src/jet/ExtensionFunction11.java b/runtime/src/jet/ExtensionFunction11.java
index 9b28dee094d..1ee2de7354a 100644
--- a/runtime/src/jet/ExtensionFunction11.java
+++ b/runtime/src/jet/ExtensionFunction11.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction11<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11);
+public interface ExtensionFunction11<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11);
 }
diff --git a/runtime/src/jet/ExtensionFunction12.java b/runtime/src/jet/ExtensionFunction12.java
index 89091ab889a..97c75a6c551 100644
--- a/runtime/src/jet/ExtensionFunction12.java
+++ b/runtime/src/jet/ExtensionFunction12.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction12<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12);
+public interface ExtensionFunction12<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12);
 }
diff --git a/runtime/src/jet/ExtensionFunction13.java b/runtime/src/jet/ExtensionFunction13.java
index 526627e804f..a54a952cc99 100644
--- a/runtime/src/jet/ExtensionFunction13.java
+++ b/runtime/src/jet/ExtensionFunction13.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction13<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13);
+public interface ExtensionFunction13<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13);
 }
diff --git a/runtime/src/jet/ExtensionFunction14.java b/runtime/src/jet/ExtensionFunction14.java
index 6af2383d733..91de2eb4d47 100644
--- a/runtime/src/jet/ExtensionFunction14.java
+++ b/runtime/src/jet/ExtensionFunction14.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction14<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14);
+public interface ExtensionFunction14<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14);
 }
diff --git a/runtime/src/jet/ExtensionFunction15.java b/runtime/src/jet/ExtensionFunction15.java
index 7ae3e23d041..95ec651b6a8 100644
--- a/runtime/src/jet/ExtensionFunction15.java
+++ b/runtime/src/jet/ExtensionFunction15.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction15<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15);
+public interface ExtensionFunction15<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15);
 }
diff --git a/runtime/src/jet/ExtensionFunction16.java b/runtime/src/jet/ExtensionFunction16.java
index e95db560a34..553c798e1b1 100644
--- a/runtime/src/jet/ExtensionFunction16.java
+++ b/runtime/src/jet/ExtensionFunction16.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction16<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16);
+public interface ExtensionFunction16<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16);
 }
diff --git a/runtime/src/jet/ExtensionFunction17.java b/runtime/src/jet/ExtensionFunction17.java
index 7a5b704a65d..77fef39818a 100644
--- a/runtime/src/jet/ExtensionFunction17.java
+++ b/runtime/src/jet/ExtensionFunction17.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction17<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17);
+public interface ExtensionFunction17<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17);
 }
diff --git a/runtime/src/jet/ExtensionFunction18.java b/runtime/src/jet/ExtensionFunction18.java
index 83050783732..54b8cdcc448 100644
--- a/runtime/src/jet/ExtensionFunction18.java
+++ b/runtime/src/jet/ExtensionFunction18.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction18<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18);
+public interface ExtensionFunction18<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18);
 }
diff --git a/runtime/src/jet/ExtensionFunction19.java b/runtime/src/jet/ExtensionFunction19.java
index 2af7d1dc207..ddec083d7c2 100644
--- a/runtime/src/jet/ExtensionFunction19.java
+++ b/runtime/src/jet/ExtensionFunction19.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction19<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19);
+public interface ExtensionFunction19<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19);
 }
diff --git a/runtime/src/jet/ExtensionFunction2.java b/runtime/src/jet/ExtensionFunction2.java
index 8895b7baaaf..7bea4f5fbf6 100644
--- a/runtime/src/jet/ExtensionFunction2.java
+++ b/runtime/src/jet/ExtensionFunction2.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction2<T, P1, P2, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2);
+public interface ExtensionFunction2<T, P1, P2, R> {
+    R invoke(T receiver, P1 p1, P2 p2);
 }
diff --git a/runtime/src/jet/ExtensionFunction20.java b/runtime/src/jet/ExtensionFunction20.java
index 075d3aabbd8..b22762d5fac 100644
--- a/runtime/src/jet/ExtensionFunction20.java
+++ b/runtime/src/jet/ExtensionFunction20.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction20<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20);
+public interface ExtensionFunction20<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20);
 }
diff --git a/runtime/src/jet/ExtensionFunction21.java b/runtime/src/jet/ExtensionFunction21.java
index 54202f161a1..4e0e49692e7 100644
--- a/runtime/src/jet/ExtensionFunction21.java
+++ b/runtime/src/jet/ExtensionFunction21.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction21<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20, P21 p21);
+public interface ExtensionFunction21<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20, P21 p21);
 }
diff --git a/runtime/src/jet/ExtensionFunction22.java b/runtime/src/jet/ExtensionFunction22.java
index d16ca136ca8..7b558139df6 100644
--- a/runtime/src/jet/ExtensionFunction22.java
+++ b/runtime/src/jet/ExtensionFunction22.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction22<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20, P21 p21, P22 p22);
+public interface ExtensionFunction22<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20, P21 p21, P22 p22);
 }
diff --git a/runtime/src/jet/ExtensionFunction3.java b/runtime/src/jet/ExtensionFunction3.java
index 10c50ea6147..ec6facc893a 100644
--- a/runtime/src/jet/ExtensionFunction3.java
+++ b/runtime/src/jet/ExtensionFunction3.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction3<T, P1, P2, P3, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3);
+public interface ExtensionFunction3<T, P1, P2, P3, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3);
 }
diff --git a/runtime/src/jet/ExtensionFunction4.java b/runtime/src/jet/ExtensionFunction4.java
index ddae3a14727..18ad38dedd0 100644
--- a/runtime/src/jet/ExtensionFunction4.java
+++ b/runtime/src/jet/ExtensionFunction4.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction4<T, P1, P2, P3, P4, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4);
+public interface ExtensionFunction4<T, P1, P2, P3, P4, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4);
 }
diff --git a/runtime/src/jet/ExtensionFunction5.java b/runtime/src/jet/ExtensionFunction5.java
index 1553e4d52de..731c201abcb 100644
--- a/runtime/src/jet/ExtensionFunction5.java
+++ b/runtime/src/jet/ExtensionFunction5.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction5<T, P1, P2, P3, P4, P5, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5);
+public interface ExtensionFunction5<T, P1, P2, P3, P4, P5, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5);
 }
diff --git a/runtime/src/jet/ExtensionFunction6.java b/runtime/src/jet/ExtensionFunction6.java
index 80c66899d68..f6d1fceaace 100644
--- a/runtime/src/jet/ExtensionFunction6.java
+++ b/runtime/src/jet/ExtensionFunction6.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction6<T, P1, P2, P3, P4, P5, P6, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6);
+public interface ExtensionFunction6<T, P1, P2, P3, P4, P5, P6, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6);
 }
diff --git a/runtime/src/jet/ExtensionFunction7.java b/runtime/src/jet/ExtensionFunction7.java
index e0517231d3e..7d10425c728 100644
--- a/runtime/src/jet/ExtensionFunction7.java
+++ b/runtime/src/jet/ExtensionFunction7.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction7<T, P1, P2, P3, P4, P5, P6, P7, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7);
+public interface ExtensionFunction7<T, P1, P2, P3, P4, P5, P6, P7, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7);
 }
diff --git a/runtime/src/jet/ExtensionFunction8.java b/runtime/src/jet/ExtensionFunction8.java
index 63fbcc2d1fa..77768dcdb74 100644
--- a/runtime/src/jet/ExtensionFunction8.java
+++ b/runtime/src/jet/ExtensionFunction8.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction8<T, P1, P2, P3, P4, P5, P6, P7, P8, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8);
+public interface ExtensionFunction8<T, P1, P2, P3, P4, P5, P6, P7, P8, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8);
 }
diff --git a/runtime/src/jet/ExtensionFunction9.java b/runtime/src/jet/ExtensionFunction9.java
index 9f26b835c0b..9e4a8dfb081 100644
--- a/runtime/src/jet/ExtensionFunction9.java
+++ b/runtime/src/jet/ExtensionFunction9.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class ExtensionFunction9<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, R> extends DefaultJetObject {
-    public abstract R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9);
+public interface ExtensionFunction9<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, R> {
+    R invoke(T receiver, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9);
 }
diff --git a/runtime/src/jet/ExtensionFunctionImpl0.java b/runtime/src/jet/ExtensionFunctionImpl0.java
new file mode 100644
index 00000000000..8524cd84a4e
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl0.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl0<T, R> extends DefaultJetObject implements ExtensionFunction0<T, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl1.java b/runtime/src/jet/ExtensionFunctionImpl1.java
new file mode 100644
index 00000000000..b8553352e98
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl1.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl1<T, P1, R> extends DefaultJetObject implements ExtensionFunction1<T, P1, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl10.java b/runtime/src/jet/ExtensionFunctionImpl10.java
new file mode 100644
index 00000000000..a7d5683fb65
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl10.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl10<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, R> extends DefaultJetObject implements ExtensionFunction10<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl11.java b/runtime/src/jet/ExtensionFunctionImpl11.java
new file mode 100644
index 00000000000..3d13aaf7f6c
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl11.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl11<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, R> extends DefaultJetObject implements ExtensionFunction11<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl12.java b/runtime/src/jet/ExtensionFunctionImpl12.java
new file mode 100644
index 00000000000..8aa75bdaec7
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl12.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl12<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, R> extends DefaultJetObject implements ExtensionFunction12<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl13.java b/runtime/src/jet/ExtensionFunctionImpl13.java
new file mode 100644
index 00000000000..04b3df87fa8
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl13.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl13<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, R> extends DefaultJetObject implements ExtensionFunction13<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl14.java b/runtime/src/jet/ExtensionFunctionImpl14.java
new file mode 100644
index 00000000000..bf58458ffa4
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl14.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl14<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, R> extends DefaultJetObject implements ExtensionFunction14<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl15.java b/runtime/src/jet/ExtensionFunctionImpl15.java
new file mode 100644
index 00000000000..25fcde8dac9
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl15.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl15<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, R> extends DefaultJetObject implements ExtensionFunction15<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl16.java b/runtime/src/jet/ExtensionFunctionImpl16.java
new file mode 100644
index 00000000000..f062c501668
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl16.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl16<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, R> extends DefaultJetObject implements ExtensionFunction16<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl17.java b/runtime/src/jet/ExtensionFunctionImpl17.java
new file mode 100644
index 00000000000..94e2cbb75f9
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl17.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl17<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, R> extends DefaultJetObject implements ExtensionFunction17<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl18.java b/runtime/src/jet/ExtensionFunctionImpl18.java
new file mode 100644
index 00000000000..89c76b1c0c6
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl18.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl18<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, R> extends DefaultJetObject implements ExtensionFunction18<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl19.java b/runtime/src/jet/ExtensionFunctionImpl19.java
new file mode 100644
index 00000000000..4825ceadfc5
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl19.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl19<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, R> extends DefaultJetObject implements ExtensionFunction19<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl2.java b/runtime/src/jet/ExtensionFunctionImpl2.java
new file mode 100644
index 00000000000..73bca5f3f7c
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl2.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl2<T, P1, P2, R> extends DefaultJetObject implements ExtensionFunction2<T, P1, P2, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl20.java b/runtime/src/jet/ExtensionFunctionImpl20.java
new file mode 100644
index 00000000000..dd396b4c197
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl20.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl20<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, R> extends DefaultJetObject implements ExtensionFunction20<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl21.java b/runtime/src/jet/ExtensionFunctionImpl21.java
new file mode 100644
index 00000000000..b9c89e3391b
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl21.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl21<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, R> extends DefaultJetObject implements ExtensionFunction21<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl22.java b/runtime/src/jet/ExtensionFunctionImpl22.java
new file mode 100644
index 00000000000..26e7d52c4f0
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl22.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl22<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22, R> extends DefaultJetObject implements ExtensionFunction22<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl3.java b/runtime/src/jet/ExtensionFunctionImpl3.java
new file mode 100644
index 00000000000..cacdca97e6b
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl3.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl3<T, P1, P2, P3, R> extends DefaultJetObject implements ExtensionFunction3<T, P1, P2, P3, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl4.java b/runtime/src/jet/ExtensionFunctionImpl4.java
new file mode 100644
index 00000000000..66d187e8b6e
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl4.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl4<T, P1, P2, P3, P4, R> extends DefaultJetObject implements ExtensionFunction4<T, P1, P2, P3, P4, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl5.java b/runtime/src/jet/ExtensionFunctionImpl5.java
new file mode 100644
index 00000000000..dc0a6771041
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl5.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl5<T, P1, P2, P3, P4, P5, R> extends DefaultJetObject implements ExtensionFunction5<T, P1, P2, P3, P4, P5, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl6.java b/runtime/src/jet/ExtensionFunctionImpl6.java
new file mode 100644
index 00000000000..275931c6911
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl6.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl6<T, P1, P2, P3, P4, P5, P6, R> extends DefaultJetObject implements ExtensionFunction6<T, P1, P2, P3, P4, P5, P6, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl7.java b/runtime/src/jet/ExtensionFunctionImpl7.java
new file mode 100644
index 00000000000..e8a744b3fad
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl7.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl7<T, P1, P2, P3, P4, P5, P6, P7, R> extends DefaultJetObject implements ExtensionFunction7<T, P1, P2, P3, P4, P5, P6, P7, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl8.java b/runtime/src/jet/ExtensionFunctionImpl8.java
new file mode 100644
index 00000000000..7de6683e746
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl8.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl8<T, P1, P2, P3, P4, P5, P6, P7, P8, R> extends DefaultJetObject implements ExtensionFunction8<T, P1, P2, P3, P4, P5, P6, P7, P8, R> {
+}
diff --git a/runtime/src/jet/ExtensionFunctionImpl9.java b/runtime/src/jet/ExtensionFunctionImpl9.java
new file mode 100644
index 00000000000..3b0f78b9122
--- /dev/null
+++ b/runtime/src/jet/ExtensionFunctionImpl9.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class ExtensionFunctionImpl9<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, R> extends DefaultJetObject implements ExtensionFunction9<T, P1, P2, P3, P4, P5, P6, P7, P8, P9, R> {
+}
diff --git a/runtime/src/jet/Function0.java b/runtime/src/jet/Function0.java
index eeb6cc9a2ef..cc53dd134a5 100644
--- a/runtime/src/jet/Function0.java
+++ b/runtime/src/jet/Function0.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function0<R> extends DefaultJetObject {
-    public abstract R invoke();
+public interface Function0<R> {
+    R invoke();
 }
diff --git a/runtime/src/jet/Function1.java b/runtime/src/jet/Function1.java
index da45cfa24e8..edd8a05faf7 100644
--- a/runtime/src/jet/Function1.java
+++ b/runtime/src/jet/Function1.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function1<P1, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1);
+public interface Function1<P1, R> {
+    R invoke(P1 p1);
 }
diff --git a/runtime/src/jet/Function10.java b/runtime/src/jet/Function10.java
index 91631b601fe..c2a9a394b3f 100644
--- a/runtime/src/jet/Function10.java
+++ b/runtime/src/jet/Function10.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function10<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10);
+public interface Function10<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10);
 }
diff --git a/runtime/src/jet/Function11.java b/runtime/src/jet/Function11.java
index c4f89cc5237..81c3bc428a8 100644
--- a/runtime/src/jet/Function11.java
+++ b/runtime/src/jet/Function11.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function11<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11);
+public interface Function11<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11);
 }
diff --git a/runtime/src/jet/Function12.java b/runtime/src/jet/Function12.java
index 860c0d7c33e..ec5a8bcf9c0 100644
--- a/runtime/src/jet/Function12.java
+++ b/runtime/src/jet/Function12.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function12<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12);
+public interface Function12<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12);
 }
diff --git a/runtime/src/jet/Function13.java b/runtime/src/jet/Function13.java
index b0ed559940f..9093239a509 100644
--- a/runtime/src/jet/Function13.java
+++ b/runtime/src/jet/Function13.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function13<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13);
+public interface Function13<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13);
 }
diff --git a/runtime/src/jet/Function14.java b/runtime/src/jet/Function14.java
index bfc346555b5..116b5cdf797 100644
--- a/runtime/src/jet/Function14.java
+++ b/runtime/src/jet/Function14.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function14<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14);
+public interface Function14<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14);
 }
diff --git a/runtime/src/jet/Function15.java b/runtime/src/jet/Function15.java
index 17036f39e59..aca4035d148 100644
--- a/runtime/src/jet/Function15.java
+++ b/runtime/src/jet/Function15.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function15<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15);
+public interface Function15<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15);
 }
diff --git a/runtime/src/jet/Function16.java b/runtime/src/jet/Function16.java
index 6bbf95c6380..47a1ec7c5c2 100644
--- a/runtime/src/jet/Function16.java
+++ b/runtime/src/jet/Function16.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function16<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16);
+public interface Function16<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16);
 }
diff --git a/runtime/src/jet/Function17.java b/runtime/src/jet/Function17.java
index 64e5dc1d43f..bd1010889bd 100644
--- a/runtime/src/jet/Function17.java
+++ b/runtime/src/jet/Function17.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function17<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17);
+public interface Function17<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17);
 }
diff --git a/runtime/src/jet/Function18.java b/runtime/src/jet/Function18.java
index a4543c13b0b..2333f9b0a75 100644
--- a/runtime/src/jet/Function18.java
+++ b/runtime/src/jet/Function18.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function18<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18);
+public interface Function18<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18);
 }
diff --git a/runtime/src/jet/Function19.java b/runtime/src/jet/Function19.java
index b797bc2af72..d6ed60062da 100644
--- a/runtime/src/jet/Function19.java
+++ b/runtime/src/jet/Function19.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function19<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19);
+public interface Function19<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19);
 }
diff --git a/runtime/src/jet/Function2.java b/runtime/src/jet/Function2.java
index a3826ba5351..3a8cb702094 100644
--- a/runtime/src/jet/Function2.java
+++ b/runtime/src/jet/Function2.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function2<P1, P2, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2);
+public interface Function2<P1, P2, R> {
+    R invoke(P1 p1, P2 p2);
 }
diff --git a/runtime/src/jet/Function20.java b/runtime/src/jet/Function20.java
index 4cb897f9b31..23c1e277e80 100644
--- a/runtime/src/jet/Function20.java
+++ b/runtime/src/jet/Function20.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function20<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20);
+public interface Function20<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20);
 }
diff --git a/runtime/src/jet/Function21.java b/runtime/src/jet/Function21.java
index d59daa08476..5d2da22875b 100644
--- a/runtime/src/jet/Function21.java
+++ b/runtime/src/jet/Function21.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function21<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20, P21 p21);
+public interface Function21<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20, P21 p21);
 }
diff --git a/runtime/src/jet/Function22.java b/runtime/src/jet/Function22.java
index 0fbb735c77f..b35bd0e0478 100644
--- a/runtime/src/jet/Function22.java
+++ b/runtime/src/jet/Function22.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function22<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20, P21 p21, P22 p22);
+public interface Function22<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9, P10 p10, P11 p11, P12 p12, P13 p13, P14 p14, P15 p15, P16 p16, P17 p17, P18 p18, P19 p19, P20 p20, P21 p21, P22 p22);
 }
diff --git a/runtime/src/jet/Function3.java b/runtime/src/jet/Function3.java
index 3664c15aa9b..17754e2f232 100644
--- a/runtime/src/jet/Function3.java
+++ b/runtime/src/jet/Function3.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function3<P1, P2, P3, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3);
+public interface Function3<P1, P2, P3, R> {
+    R invoke(P1 p1, P2 p2, P3 p3);
 }
diff --git a/runtime/src/jet/Function4.java b/runtime/src/jet/Function4.java
index db32f50473b..2517c14dfb7 100644
--- a/runtime/src/jet/Function4.java
+++ b/runtime/src/jet/Function4.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function4<P1, P2, P3, P4, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4);
+public interface Function4<P1, P2, P3, P4, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4);
 }
diff --git a/runtime/src/jet/Function5.java b/runtime/src/jet/Function5.java
index 9c6cba56381..ef3efbee626 100644
--- a/runtime/src/jet/Function5.java
+++ b/runtime/src/jet/Function5.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function5<P1, P2, P3, P4, P5, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5);
+public interface Function5<P1, P2, P3, P4, P5, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5);
 }
diff --git a/runtime/src/jet/Function6.java b/runtime/src/jet/Function6.java
index fe84516d5cf..47a16a6e4dd 100644
--- a/runtime/src/jet/Function6.java
+++ b/runtime/src/jet/Function6.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function6<P1, P2, P3, P4, P5, P6, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6);
+public interface Function6<P1, P2, P3, P4, P5, P6, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6);
 }
diff --git a/runtime/src/jet/Function7.java b/runtime/src/jet/Function7.java
index dd565930506..a231b8441f5 100644
--- a/runtime/src/jet/Function7.java
+++ b/runtime/src/jet/Function7.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function7<P1, P2, P3, P4, P5, P6, P7, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7);
+public interface Function7<P1, P2, P3, P4, P5, P6, P7, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7);
 }
diff --git a/runtime/src/jet/Function8.java b/runtime/src/jet/Function8.java
index 875756c4912..7967fcd77b8 100644
--- a/runtime/src/jet/Function8.java
+++ b/runtime/src/jet/Function8.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function8<P1, P2, P3, P4, P5, P6, P7, P8, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8);
+public interface Function8<P1, P2, P3, P4, P5, P6, P7, P8, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8);
 }
diff --git a/runtime/src/jet/Function9.java b/runtime/src/jet/Function9.java
index ebb647868c9..0bade772321 100644
--- a/runtime/src/jet/Function9.java
+++ b/runtime/src/jet/Function9.java
@@ -19,6 +19,6 @@ package jet;
 import org.jetbrains.jet.rt.annotation.AssertInvisibleInResolver;
 
 @AssertInvisibleInResolver
-public abstract class Function9<P1, P2, P3, P4, P5, P6, P7, P8, P9, R> extends DefaultJetObject {
-    public abstract R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9);
+public interface Function9<P1, P2, P3, P4, P5, P6, P7, P8, P9, R> {
+    R invoke(P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6, P7 p7, P8 p8, P9 p9);
 }
diff --git a/runtime/src/jet/FunctionImpl0.java b/runtime/src/jet/FunctionImpl0.java
new file mode 100644
index 00000000000..8e3a9474c59
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl0.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl0<R> extends DefaultJetObject implements Function0<R> {
+}
diff --git a/runtime/src/jet/FunctionImpl1.java b/runtime/src/jet/FunctionImpl1.java
new file mode 100644
index 00000000000..e6f13d5f88f
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl1.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl1<P1, R> extends DefaultJetObject implements Function1<P1, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl10.java b/runtime/src/jet/FunctionImpl10.java
new file mode 100644
index 00000000000..2e264de780f
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl10.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl10<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, R> extends DefaultJetObject implements Function10<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl11.java b/runtime/src/jet/FunctionImpl11.java
new file mode 100644
index 00000000000..ad08b2973f3
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl11.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl11<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, R> extends DefaultJetObject implements Function11<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl12.java b/runtime/src/jet/FunctionImpl12.java
new file mode 100644
index 00000000000..0365ff25c33
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl12.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl12<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, R> extends DefaultJetObject implements Function12<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl13.java b/runtime/src/jet/FunctionImpl13.java
new file mode 100644
index 00000000000..dcdfa2853d7
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl13.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl13<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, R> extends DefaultJetObject implements Function13<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl14.java b/runtime/src/jet/FunctionImpl14.java
new file mode 100644
index 00000000000..f6b038848bb
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl14.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl14<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, R> extends DefaultJetObject implements Function14<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl15.java b/runtime/src/jet/FunctionImpl15.java
new file mode 100644
index 00000000000..2a8e294fc0f
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl15.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl15<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, R> extends DefaultJetObject implements Function15<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl16.java b/runtime/src/jet/FunctionImpl16.java
new file mode 100644
index 00000000000..93c0983a727
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl16.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl16<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, R> extends DefaultJetObject implements Function16<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl17.java b/runtime/src/jet/FunctionImpl17.java
new file mode 100644
index 00000000000..6de4c517c5e
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl17.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl17<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, R> extends DefaultJetObject implements Function17<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl18.java b/runtime/src/jet/FunctionImpl18.java
new file mode 100644
index 00000000000..a850e14ab08
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl18.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl18<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, R> extends DefaultJetObject implements Function18<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl19.java b/runtime/src/jet/FunctionImpl19.java
new file mode 100644
index 00000000000..e79e39088ab
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl19.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl19<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, R> extends DefaultJetObject implements Function19<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl2.java b/runtime/src/jet/FunctionImpl2.java
new file mode 100644
index 00000000000..c4807dde544
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl2.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl2<P1, P2, R> extends DefaultJetObject implements Function2<P1, P2, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl20.java b/runtime/src/jet/FunctionImpl20.java
new file mode 100644
index 00000000000..93507834dc5
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl20.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl20<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, R> extends DefaultJetObject implements Function20<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl21.java b/runtime/src/jet/FunctionImpl21.java
new file mode 100644
index 00000000000..c227caebc04
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl21.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl21<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, R> extends DefaultJetObject implements Function21<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl22.java b/runtime/src/jet/FunctionImpl22.java
new file mode 100644
index 00000000000..a3fbc333b9d
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl22.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl22<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22, R> extends DefaultJetObject implements Function22<P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl3.java b/runtime/src/jet/FunctionImpl3.java
new file mode 100644
index 00000000000..1ff55eaa615
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl3.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl3<P1, P2, P3, R> extends DefaultJetObject implements Function3<P1, P2, P3, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl4.java b/runtime/src/jet/FunctionImpl4.java
new file mode 100644
index 00000000000..fe26537320e
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl4.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl4<P1, P2, P3, P4, R> extends DefaultJetObject implements Function4<P1, P2, P3, P4, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl5.java b/runtime/src/jet/FunctionImpl5.java
new file mode 100644
index 00000000000..36413b9c05f
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl5.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl5<P1, P2, P3, P4, P5, R> extends DefaultJetObject implements Function5<P1, P2, P3, P4, P5, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl6.java b/runtime/src/jet/FunctionImpl6.java
new file mode 100644
index 00000000000..61de172e525
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl6.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl6<P1, P2, P3, P4, P5, P6, R> extends DefaultJetObject implements Function6<P1, P2, P3, P4, P5, P6, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl7.java b/runtime/src/jet/FunctionImpl7.java
new file mode 100644
index 00000000000..995f104870c
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl7.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl7<P1, P2, P3, P4, P5, P6, P7, R> extends DefaultJetObject implements Function7<P1, P2, P3, P4, P5, P6, P7, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl8.java b/runtime/src/jet/FunctionImpl8.java
new file mode 100644
index 00000000000..6952ef4138c
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl8.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl8<P1, P2, P3, P4, P5, P6, P7, P8, R> extends DefaultJetObject implements Function8<P1, P2, P3, P4, P5, P6, P7, P8, R> {
+}
diff --git a/runtime/src/jet/FunctionImpl9.java b/runtime/src/jet/FunctionImpl9.java
new file mode 100644
index 00000000000..cc3bec590f3
--- /dev/null
+++ b/runtime/src/jet/FunctionImpl9.java
@@ -0,0 +1,20 @@
+/*
+ * 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 jet;
+
+public abstract class FunctionImpl9<P1, P2, P3, P4, P5, P6, P7, P8, P9, R> extends DefaultJetObject implements Function9<P1, P2, P3, P4, P5, P6, P7, P8, P9, R> {
+}