diff --git a/querydsl-collections/src/main/java/com/mysema/query/collections/ColQueryFunctions.java b/querydsl-collections/src/main/java/com/mysema/query/collections/ColQueryFunctions.java
index 14e406e75..665194d35 100644
--- a/querydsl-collections/src/main/java/com/mysema/query/collections/ColQueryFunctions.java
+++ b/querydsl-collections/src/main/java/com/mysema/query/collections/ColQueryFunctions.java
@@ -3,10 +3,17 @@ package com.mysema.query.collections;
 import java.util.Calendar;
 import java.util.Date;
 
+import javax.annotation.Nullable;
+
+/**
+ * @author tiwe
+ *
+ */
 public final class ColQueryFunctions {
     
     private ColQueryFunctions(){}
     
+    @Nullable
     public static <T> T coalesce(T... args){
         for (T arg : args){
             if (arg != null){
diff --git a/querydsl-core/src/main/java/com/mysema/query/types/expr/Coalesce.java b/querydsl-core/src/main/java/com/mysema/query/types/expr/Coalesce.java
index a5cca1570..93560074f 100644
--- a/querydsl-core/src/main/java/com/mysema/query/types/expr/Coalesce.java
+++ b/querydsl-core/src/main/java/com/mysema/query/types/expr/Coalesce.java
@@ -21,7 +21,8 @@ import com.mysema.query.types.Visitor;
  * 
  * @param <T>
  */
-public class Coalesce<T> extends ESimple<T>{
+@SuppressWarnings("unchecked")
+public class Coalesce<T extends Comparable> extends EComparable<T>{
     
     private static final long serialVersionUID = 445439522266250417L;
     
@@ -32,32 +33,47 @@ public class Coalesce<T> extends ESimple<T>{
         add(exprs);
     }
 
-    @SuppressWarnings("unchecked")
     public Coalesce(Expr<T> ...exprs){
         this((Class<T>)(exprs.length > 0 ? exprs[0].getType() : Object.class), exprs);
     }
     
+    @Override
+    public void accept(Visitor v) {                
+        OSimple.create(getType(), Ops.COALESCE, getExpressionList()).accept(v);
+    }
+    
     public Coalesce<T> add(Expr<T>... exprs){
         for (Expr<T> expr : exprs){
             this.exprs.add(expr);
         }
         return this;
     }
-    
+     
     public Coalesce<T> add(T constant){
         this.exprs.add(ExprConst.create(constant));
         return this;
     }
-        
-    @Override
-    public void accept(Visitor v) {
-        Expr<?> arg = exprs.get(0);
-        for (int i = 1; i < exprs.size(); i++){
-            arg = OSimple.create(List.class, Ops.LIST, arg, exprs.get(i));
-        }        
-        OSimple.create(getType(), Ops.COALESCE, arg).accept(v);
+    
+    public EDate<T> asDate(){
+        return (EDate<T>) ODate.create(getType(), Ops.COALESCE, getExpressionList());                
     }
-
+    
+    public EDateTime<T> asDateTime(){
+        return (EDateTime<T>) ODateTime.create(getType(), Ops.COALESCE, getExpressionList());                
+    }
+    
+    public ENumber<?> asNumber(){
+        return ONumber.create((Class)getType(), Ops.COALESCE, getExpressionList());                
+    }
+    
+    public EString asString(){
+        return OString.create(Ops.COALESCE, getExpressionList());
+    }
+    
+    public ETime<T> asTime(){
+        return (ETime<T>) OTime.create(getType(), Ops.COALESCE, getExpressionList());                
+    }
+    
     @Override
     public boolean equals(Object o) {
         if (o == this){
@@ -70,4 +86,17 @@ public class Coalesce<T> extends ESimple<T>{
         }
     }
 
+    @Override
+    public int hashCode(){
+        return exprs.hashCode();
+    }
+    
+    private Expr<?> getExpressionList(){
+        Expr<?> arg = exprs.get(0);
+        for (int i = 1; i < exprs.size(); i++){
+            arg = OSimple.create(List.class, Ops.LIST, arg, exprs.get(i));
+        }
+        return arg;
+    }
+
 }
diff --git a/querydsl-core/src/main/java/com/mysema/query/types/expr/OBoolean.java b/querydsl-core/src/main/java/com/mysema/query/types/expr/OBoolean.java
index 0ef290757..82b4446d3 100644
--- a/querydsl-core/src/main/java/com/mysema/query/types/expr/OBoolean.java
+++ b/querydsl-core/src/main/java/com/mysema/query/types/expr/OBoolean.java
@@ -24,17 +24,17 @@ public class OBoolean extends EBoolean implements Operation<Boolean> {
 
     private static final long serialVersionUID = 7432281499861357581L;
 
-    public static EBoolean create(Operator<Boolean> op, Expr<?>... args){
+    public static EBoolean create(Operator<? super Boolean> op, Expr<?>... args){
         return new OBoolean(op, args);
     }
    
     private final Operation<Boolean> opMixin;
     
-    OBoolean(Operator<Boolean> op, Expr<?>... args) {
+    OBoolean(Operator<? super Boolean> op, Expr<?>... args) {
         this(op, Arrays.asList(args));
     }
     
-    OBoolean(Operator<Boolean> op, List<Expr<?>> args) {
+    OBoolean(Operator<? super Boolean> op, List<Expr<?>> args) {
         opMixin = new OperationMixin<Boolean>(this, op, args);
     }
 
diff --git a/querydsl-core/src/main/java/com/mysema/query/types/expr/OString.java b/querydsl-core/src/main/java/com/mysema/query/types/expr/OString.java
index 608db8590..416dd3db7 100644
--- a/querydsl-core/src/main/java/com/mysema/query/types/expr/OString.java
+++ b/querydsl-core/src/main/java/com/mysema/query/types/expr/OString.java
@@ -23,17 +23,17 @@ public class OString extends EString implements Operation<String> {
     
     private static final long serialVersionUID = 6846556373847139549L;
 
-    public static EString create(Operator<String> op, Expr<?>... args){
+    public static EString create(Operator<? super String> op, Expr<?>... args){
         return new OString(op, args);
     }
     
     private final Operation<String> opMixin;
 
-    OString(Operator<String> op, Expr<?>... args) {
+    OString(Operator<? super String> op, Expr<?>... args) {
         this(op, Arrays.asList(args));
     }
 
-    OString(Operator<String> op, List<Expr<?>> args) {
+    OString(Operator<? super String> op, List<Expr<?>> args) {
         this.opMixin = new OperationMixin<String>(this, op, args);
     }
 
diff --git a/querydsl-core/src/main/java/com/mysema/util/MathUtils.java b/querydsl-core/src/main/java/com/mysema/util/MathUtils.java
index 300cc7d26..df833e723 100644
--- a/querydsl-core/src/main/java/com/mysema/util/MathUtils.java
+++ b/querydsl-core/src/main/java/com/mysema/util/MathUtils.java
@@ -45,7 +45,6 @@ public final class MathUtils {
             }else{
                 rv = new BigDecimal(num.toString());
             }
-            rv = num;
         }else if (type.equals(BigInteger.class)){
             if (num instanceof BigInteger){
                 rv = num;
diff --git a/querydsl-core/src/test/java/com/mysema/query/types/expr/CoalesceTest.java b/querydsl-core/src/test/java/com/mysema/query/types/expr/CoalesceTest.java
index d3f10d085..5f8c4cae3 100644
--- a/querydsl-core/src/test/java/com/mysema/query/types/expr/CoalesceTest.java
+++ b/querydsl-core/src/test/java/com/mysema/query/types/expr/CoalesceTest.java
@@ -1,26 +1,39 @@
 package com.mysema.query.types.expr;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
 
 import org.junit.Test;
 
 import com.mysema.query.types.path.PString;
 
+@SuppressWarnings("unchecked")
 public class CoalesceTest {
     
-    @SuppressWarnings("unchecked")
+    PString firstname = new PString("firstname");
+    
+    PString lastname = new PString("lastname");
+    
     @Test
-    public void withList(){
-        PString firstname = new PString("firstname");
-        PString lastname = new PString("lastname");
+    public void withList(){        
         Coalesce<String> c = new Coalesce<String>(firstname, lastname).add("xxx");
         assertEquals("coalesce(firstname, lastname, xxx)", c.toString());
     }
-
-    @SuppressWarnings("unchecked")
+    
     @Test
     public void withSingleArg(){
         Coalesce<String> c = new Coalesce<String>().add("xxx");
         assertEquals("coalesce(xxx)", c.toString());
     }
+    
+    @Test
+    public void asComparable(){
+        Coalesce<String> c = new Coalesce<String>(firstname, lastname);       
+        c.asc();
+    }
+    
+    @Test
+    public void asString(){
+        Coalesce<String> c = new Coalesce<String>(firstname, lastname);
+        c.asString().lower();
+    }
 }