diff --git a/runtime/src/jet/StringTemplate.java b/runtime/src/jet/StringTemplate.java
index 5ac79e4bb44..218216b005a 100644
--- a/runtime/src/jet/StringTemplate.java
+++ b/runtime/src/jet/StringTemplate.java
@@ -20,10 +20,10 @@ package jet;
  *
  * It is represented as an object that contains a Tuple
  */
-public class StringTemplate<T extends Tuple> {
-    private final T tuple;
+public class StringTemplate {
+    private final Tuple tuple;
 
-    public StringTemplate(T tuple) {
+    public StringTemplate(Tuple tuple) {
         this.tuple = tuple;
     }
 
@@ -50,11 +50,11 @@ public class StringTemplate<T extends Tuple> {
     @Override
     public String toString() {
         final StringBuilder builder = new StringBuilder();
-        tuple.forEach(new Function1<Object,Void>(){
+        tuple.forEach(new Function1<Object,Tuple0>(){
             @Override
-            public Void invoke(Object o) {
+            public Tuple0 invoke(Object o) {
                 builder.append(o);
-                return null;
+                return Tuple0.INSTANCE;
             }
         });
         return builder.toString();
@@ -62,9 +62,20 @@ public class StringTemplate<T extends Tuple> {
     }
 
     /**
-     * Returns the values in the string template
+     * Returns the tuple of values in the string template
      */
-    public T getValues() {
+    public Tuple getValues() {
         return tuple;
     }
+
+
+    /**
+     * Performs the given function on each value in the string template
+     */
+    public void forEach(Function1<Object, Tuple0> fn) {
+        if (tuple != null) {
+            tuple.forEach(fn);
+        }
+    }
+
 }
diff --git a/runtime/src/jet/Tuple.java b/runtime/src/jet/Tuple.java
index 1bd6a88e794..b233471944f 100644
--- a/runtime/src/jet/Tuple.java
+++ b/runtime/src/jet/Tuple.java
@@ -23,7 +23,7 @@ public abstract class Tuple extends DefaultJetObject {
     /**
      * Performs the given function on each item in the tuple
      */
-    public abstract void forEach(Function1<Object, Void> fn);
+    public abstract void forEach(Function1<Object, Tuple0> fn);
 
     /**
      * Returns the size of the tuple
diff --git a/runtime/src/jet/Tuple0.java b/runtime/src/jet/Tuple0.java
index b45e34112e7..482426597ee 100644
--- a/runtime/src/jet/Tuple0.java
+++ b/runtime/src/jet/Tuple0.java
@@ -41,7 +41,7 @@ public class Tuple0 extends Tuple {
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
     }
 
     @Override
diff --git a/runtime/src/jet/Tuple1.java b/runtime/src/jet/Tuple1.java
index 8fef66da17d..5a088e9e855 100644
--- a/runtime/src/jet/Tuple1.java
+++ b/runtime/src/jet/Tuple1.java
@@ -46,7 +46,7 @@ public class Tuple1<T1> extends Tuple {
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
     }
 
diff --git a/runtime/src/jet/Tuple10.java b/runtime/src/jet/Tuple10.java
index 9d003073513..120ebfbe465 100644
--- a/runtime/src/jet/Tuple10.java
+++ b/runtime/src/jet/Tuple10.java
@@ -109,7 +109,7 @@ public class Tuple10<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10> extends Tuple {
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple11.java b/runtime/src/jet/Tuple11.java
index 8a61d3f8f94..70e741997a0 100644
--- a/runtime/src/jet/Tuple11.java
+++ b/runtime/src/jet/Tuple11.java
@@ -116,7 +116,7 @@ public class Tuple11<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11> extends Tuple
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple12.java b/runtime/src/jet/Tuple12.java
index e4c88c68863..0ea6abac0f8 100644
--- a/runtime/src/jet/Tuple12.java
+++ b/runtime/src/jet/Tuple12.java
@@ -123,7 +123,7 @@ public class Tuple12<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12> extends
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple13.java b/runtime/src/jet/Tuple13.java
index 1260c5a97a8..cdcc16fb4e1 100644
--- a/runtime/src/jet/Tuple13.java
+++ b/runtime/src/jet/Tuple13.java
@@ -130,7 +130,7 @@ public class Tuple13<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13> ext
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple14.java b/runtime/src/jet/Tuple14.java
index b4b9844bfb1..ffae337a2f1 100644
--- a/runtime/src/jet/Tuple14.java
+++ b/runtime/src/jet/Tuple14.java
@@ -137,7 +137,7 @@ public class Tuple14<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple15.java b/runtime/src/jet/Tuple15.java
index ff1e3e3ba80..798deadf08e 100644
--- a/runtime/src/jet/Tuple15.java
+++ b/runtime/src/jet/Tuple15.java
@@ -144,7 +144,7 @@ public class Tuple15<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple16.java b/runtime/src/jet/Tuple16.java
index bb58d53e5b7..3f0a3316759 100644
--- a/runtime/src/jet/Tuple16.java
+++ b/runtime/src/jet/Tuple16.java
@@ -151,7 +151,7 @@ public class Tuple16<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple17.java b/runtime/src/jet/Tuple17.java
index c13906360f3..9b604b69c70 100644
--- a/runtime/src/jet/Tuple17.java
+++ b/runtime/src/jet/Tuple17.java
@@ -158,7 +158,7 @@ public class Tuple17<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple18.java b/runtime/src/jet/Tuple18.java
index 74f83711b0a..e79eb14e3a3 100644
--- a/runtime/src/jet/Tuple18.java
+++ b/runtime/src/jet/Tuple18.java
@@ -165,7 +165,7 @@ public class Tuple18<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple19.java b/runtime/src/jet/Tuple19.java
index c6e982a1a3f..f3b201562ad 100644
--- a/runtime/src/jet/Tuple19.java
+++ b/runtime/src/jet/Tuple19.java
@@ -172,7 +172,7 @@ public class Tuple19<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple2.java b/runtime/src/jet/Tuple2.java
index dcdf3b0ee0e..54343ce1102 100644
--- a/runtime/src/jet/Tuple2.java
+++ b/runtime/src/jet/Tuple2.java
@@ -53,7 +53,7 @@ public class Tuple2<T1, T2> extends Tuple {
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
     }
diff --git a/runtime/src/jet/Tuple20.java b/runtime/src/jet/Tuple20.java
index 8272dce6a14..9e9c4985a03 100644
--- a/runtime/src/jet/Tuple20.java
+++ b/runtime/src/jet/Tuple20.java
@@ -179,7 +179,7 @@ public class Tuple20<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple21.java b/runtime/src/jet/Tuple21.java
index 0c7818d5cc8..46b2d881b04 100644
--- a/runtime/src/jet/Tuple21.java
+++ b/runtime/src/jet/Tuple21.java
@@ -186,7 +186,7 @@ public class Tuple21<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple22.java b/runtime/src/jet/Tuple22.java
index b0179dc4cf8..860309ea071 100644
--- a/runtime/src/jet/Tuple22.java
+++ b/runtime/src/jet/Tuple22.java
@@ -193,7 +193,7 @@ public class Tuple22<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple3.java b/runtime/src/jet/Tuple3.java
index e10694f9602..61844ff6944 100644
--- a/runtime/src/jet/Tuple3.java
+++ b/runtime/src/jet/Tuple3.java
@@ -60,7 +60,7 @@ public class Tuple3<T1, T2, T3> extends Tuple {
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple4.java b/runtime/src/jet/Tuple4.java
index 75277855bc5..3ffc4043b41 100644
--- a/runtime/src/jet/Tuple4.java
+++ b/runtime/src/jet/Tuple4.java
@@ -67,7 +67,7 @@ public class Tuple4<T1, T2, T3, T4> extends Tuple {
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple5.java b/runtime/src/jet/Tuple5.java
index e1c5180c2dd..4707e3bd99a 100644
--- a/runtime/src/jet/Tuple5.java
+++ b/runtime/src/jet/Tuple5.java
@@ -74,7 +74,7 @@ public class Tuple5<T1, T2, T3, T4, T5> extends Tuple {
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple6.java b/runtime/src/jet/Tuple6.java
index df81c44049d..75262f94c5b 100644
--- a/runtime/src/jet/Tuple6.java
+++ b/runtime/src/jet/Tuple6.java
@@ -81,7 +81,7 @@ public class Tuple6<T1, T2, T3, T4, T5, T6> extends Tuple {
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple7.java b/runtime/src/jet/Tuple7.java
index 090091b41bd..211491adbe2 100644
--- a/runtime/src/jet/Tuple7.java
+++ b/runtime/src/jet/Tuple7.java
@@ -88,7 +88,7 @@ public class Tuple7<T1, T2, T3, T4, T5, T6, T7> extends Tuple {
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple8.java b/runtime/src/jet/Tuple8.java
index 2c083bd888a..92289cecf7a 100644
--- a/runtime/src/jet/Tuple8.java
+++ b/runtime/src/jet/Tuple8.java
@@ -95,7 +95,7 @@ public class Tuple8<T1, T2, T3, T4, T5, T6, T7, T8> extends Tuple {
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);
diff --git a/runtime/src/jet/Tuple9.java b/runtime/src/jet/Tuple9.java
index e4a4175565c..1cc373502e1 100644
--- a/runtime/src/jet/Tuple9.java
+++ b/runtime/src/jet/Tuple9.java
@@ -102,7 +102,7 @@ public class Tuple9<T1, T2, T3, T4, T5, T6, T7, T8, T9> extends Tuple {
     }
 
     @Override
-    public void forEach(Function1<Object, Void> fn) {
+    public void forEach(Function1<Object, Tuple0> fn) {
         fn.invoke(_1);
         fn.invoke(_2);
         fn.invoke(_3);