diff --git a/src/include/high_level_operation.h b/src/include/high_level_operation.h
index 5dfb116..0bad1b8 100644
--- a/src/include/high_level_operation.h
+++ b/src/include/high_level_operation.h
@@ -4,33 +4,147 @@
 
 #include "base_def.h"
 #include "dynamic_operation.h"
+#include "multi_array_operation.h"
 
 namespace MultiArrayTools
 {
 
-    template <class DOp>
+    template <class DOp, class... Indices>
     class HLOBuilderBase
     {
-
+    protected:
+	//typedef typename DOp::value_type IOp;
+	DOp mDOp;
+	typedef decltype(mDOp.data()->mOp) IOpP;
+	IOpP mIOpP;
+	typedef std::shared_ptr<HLOBuilderBase<DOp>> HLOBP;
+	HLOBP mPrev;
     public:
-	virtual DOp mkDOp() const = 0;
-	virtual DynamicExpression mkGetExpr() const = 0;
+
+	HLOBuilderBase(const HLOBP& prev) : mPrev(prev) {}
+	
+	virtual void create(const std::shared_ptr<Indices>&... inds) = 0;
+
+	virtual std::shared_ptr<HLOBuilderBase<DOp,Indices...>>
+	operator*(const std::shared_ptr<HLOBuilderBase<DOp,Indices...>>& in) const = 0;
+
+	const IOpP& get() const
+	{
+	    return mIOpP;
+	}
+
+	const DOp& dget() const
+	{
+	    return mDOp;
+	}
+
+	const HLOBP& prev() const
+	{
+	    return mPrev;
+	}
+
+	void appendPrev(const HLOBP& prev)
+	{
+	    if(mPrev){
+		mPrev->append(prev);
+	    }
+	    else {
+		mPrev = prev;
+	    }
+	}
+	
+	template <class Expr>
+	DynamicExpression mkGetExpr(const Expr& expr) const
+	{
+	    if(not mPrev){
+		return DynamicExpression( mkGetExpr(mDOp, expr) );
+	    }
+	    else {
+		return DynamicExpression( mkGetExpr(mDOp, mPrev->mkGetExpr(expr) ) );
+	    }
+	}
     };
 
-    template <class DOp, class Op>
-    class HLOBuilder : public HLOBuilderBase<DOp>
+    
+    template <class DOp, class CF, class... Indices>
+    class HLOBuilder : public HLOBuilderBase<DOp,Indices...>
     {
     private:
+	typedef HLOBuilderBase<DOp,Indices...> B;
+	typedef typename B::HLOBP HLOBP;
+	CF mCF;
+    public:
+
+	HLOBuilder(const HLOBP& prev,
+		   const CF& cf) : B(prev), mCF(cf) {}
+
+	HLOBuilder(const CF& cf) : B(nullptr), mCF(cf) {}
+	
+	virtual void create(const std::shared_ptr<Indices>&... inds) override final
+	{
+	    B::mPrev->create(inds...);
+	    auto op = mCF();
+	    B::mDOp = mkDynOutOp(op, inds...);
+	    B::mIOpP = B::mDOp.data()->mOp;
+	}
+
+	virtual std::shared_ptr<B>
+	operator*(const std::shared_ptr<HLOBuilderBase<DOp,Indices...>>& in) const override final
+	{
+	    HLOBP xprev = B::mPrev;
+	    xprev->appendPrev(in->prev());
+	    xprev->append(in);
+	    xprev->appendPrev(std::make_shared<HLOBuilder<DOp,CF,Indices...>>(*this));
+	    return std::make_shared<HLOBuilder<DOp,decltype(*B::mIOpP*in->mkDOp().data()->mOp),Indices...>>
+		(xprev, [&in,this]() { this->create(); return *B::mIOpP*in->mkDOp().data()->mOp; });
+	}
+    };
+
+
+    template <class DOp, class Op, class... Indices>
+    class HLOBuilderRoot : public HLOBuilderBase<DOp,Indices...>
+    {
+    private:
+	typedef HLOBuilderBase<DOp,Indices...> B;
+	typedef typename B::HLOBP HLOBP;
 	Op mOp;
     public:
-	// ...
-	HLOBuilder(const Op& op) : mOp(op) {}
-	
-	auto operator*(const HLOBuilderBase<DOp>& in)
+
+	HLOBuilderRoot(const Op& op) : B(nullptr), mOp(op) {}
+
+	virtual void create(const std::shared_ptr<Indices>&... inds) override final
 	{
+	    //B::mPrev->create(inds...);
+	    //mOp = mCF();
+	    //B::mDOp = mkDynOutOp(op, inds...);
+	    //B::mIOpP = B::mDOp.data()->mOp;
 	}
+
+	virtual std::shared_ptr<B>
+	operator*(const std::shared_ptr<HLOBuilderBase<DOp,Indices...>>& in) const override final
+	{
+	    HLOBP xprev = in->prev();
+	    xprev->append(in);
+	    //xprev->appendPrev(in.prev());
+	    //xprev->appendPrev(std::make_shared<HLOBuilder<DOp,CF>>(*this));
+	    return std::make_shared<HLOBuilder<DOp,decltype(mOp*in->mkDOp().data()->mOp),Indices...>>
+		(xprev, [&in,this]() { this->create(); return mOp*in->mkDOp().data()->mOp; });
+	}
+    };
+
+    template <class DOp, class CF,class... Indices>
+    std::shared_ptr<HLOBuilderBase<DOp,Indices...>>
+    mkHLOBuilder( const CF& cf, const std::shared_ptr<Indices>&... inds)
+    {
+	return std::make_shared<HLOBuilder<DOp,CF,Indices...>>(cf);
+    }
+
+    template <class DOp, class Op ,class... Indices>
+    std::shared_ptr<HLOBuilderBase<DOp,Indices...>>
+    mkHLOBuilderRoot( const Op& op, const std::shared_ptr<Indices>&... inds )
+    {
+	return std::make_shared<HLOBuilderRoot<DOp,Op,Indices...>>(op);
     }
-    
 }
 
 #endif
diff --git a/src/include/multi_array_header.h b/src/include/multi_array_header.h
index 95ffbc5..6b62fbb 100644
--- a/src/include/multi_array_header.h
+++ b/src/include/multi_array_header.h
@@ -13,6 +13,7 @@
 #include "map_range.h"
 #include "dynamic_operation.h"
 //#include "expressions.h"
+#include "high_level_operation.h"
 
 #include "multi_array_header.cc.h"
 
diff --git a/src/include/xfor/xfor.h b/src/include/xfor/xfor.h
index 1bffc0f..31e94e5 100644
--- a/src/include/xfor/xfor.h
+++ b/src/include/xfor/xfor.h
@@ -457,7 +457,8 @@ namespace MultiArrayHelper
 	std::shared_ptr<ExpressionBase> mNext;
 
     public:
-	
+
+	typedef DExtT ExtType;
 	static constexpr size_t LAYER = 0;
 	static constexpr size_t SIZE = 0;
 
diff --git a/src/tests/op4_unit_test.cc b/src/tests/op4_unit_test.cc
index 253fedf..418388b 100644
--- a/src/tests/op4_unit_test.cc
+++ b/src/tests/op4_unit_test.cc
@@ -306,18 +306,29 @@ namespace
 	auto op1 = ma2(i1,di2);
 	auto op3 = ma1(i1,di1);
 	auto opr = resx4(i1,di4);
+	typedef decltype(mkDynOutOp(exp(op1), ic_1, ic_2)) DOp;
 	auto loop = mkPILoop
 	    ( [&op1,&op3,&opr,&xx,&ic_1,&ic_2,this](){
-		auto dop1 = mkDynOutOp(exp(op1), ic_1, ic_2);
-		auto op2 = *dop1.data()->mOp;
-		auto dop2 = mkDynOutOp(op3 * op2, ic_1, ic_2);
+		//auto dop1 = mkDynOutOp(exp(op1), ic_1, ic_2);
+		//auto op2 = *dop1.data()->mOp;
+		//auto dop2 = mkDynOutOp(op3 * op2, ic_1, ic_2);
+		auto dop2 = (*mkHLOBuilderRoot<DOp>( op3, ic_1, ic_2 )) * mkHLOBuilder<DOp>([&op1,this]() { return exp(op1); }, ic_1, ic_2);
+		dop2->create(ic_1,ic_2);
+		const OperationRoot<double,CI::RangeType,CI::RangeType>& yy = *dop2->get();
+		return dop2->mkGetExpr
+		    (mkILoop(std::make_tuple(dop2->dget()), std::make_tuple(ic_1, ic_2),
+			     std::make_tuple(xx),
+			     std::make_tuple(opr.assign( yy , mkMIndex(ic_1, ic_2) )),
+			     std::array<size_t,1>({1}), std::array<size_t,1>({0})));
+		/*
 		return mkGetExpr
 		    (dop1,mkGetExpr
 		     (dop2,mkILoop(std::make_tuple(*dop2.data()->mOp), std::make_tuple(ic_1, ic_2),
 				   std::make_tuple(xx),
 				   std::make_tuple(opr.assign( *dop2.data()->mOp, mkMIndex(ic_1, ic_2) )),
-				   std::array<size_t,1>({1}), std::array<size_t,1>({0})))); } );
-	
+				   std::array<size_t,1>({1}), std::array<size_t,1>({0}))));
+		*/
+	    } );
         mi->pifor(1,loop)();
         
 	auto i2_1 = imap.at("i2_1");