diff --git a/src/include/operation/op_types.cc.h b/src/include/operation/op_types.cc.h
index 62419e7..4df3517 100644
--- a/src/include/operation/op_types.cc.h
+++ b/src/include/operation/op_types.cc.h
@@ -164,12 +164,6 @@ namespace CNORXZ
 	return xpr;
     }
 
-    template <typename T, class IndexT>
-    T* OpRoot<T,IndexT>::data() const
-    {
-        return mData;
-    }
-
 
     /*******************
      *   Operation     *
@@ -210,26 +204,6 @@ namespace CNORXZ
 	}
     }
 
-    template <size_t I, typename V, class OpFunction, class ETuple, class OpTuple, typename... Args>
-    inline auto
-    mkVOpExpr(std::shared_ptr<OpFunction> f, const ETuple& pos, const OpTuple& ops, Args... args)
-    {
-	if constexpr(I == std::tuple_size<OpTuple>{}){
-	    if constexpr(OpFunction::FISSTATIC){
-		return VFunc<OpFunction>::apply(args...);
-	    }
-	    else {
-		auto vf = mkVFuncPtr(f);
-		(*vf)(args...);
-	    }
-	}
-	else {
-	    typedef typename std::remove_reference<decltype(std::get<I>(ops))>::type NextOpType;
-	    return mkVOpExpr<I+1,V>( f, getX<NextOpType::SIZE>(pos), ops, args...,
-				     std::get<I>(ops).template vget<V>(pos));
-	}
-    }
-
     template <typename T, class OpFunction, class... Ops>
     template <class ET>
     inline auto Operation<T,OpFunction,Ops...>::get(ET pos) const
@@ -284,51 +258,38 @@ namespace CNORXZ
      *   Contraction     *
      *********************/
 
-    template <typename T, class Op, class IndexType>
-    Contraction<T,Op,IndexType>::Contraction(const Op& op, std::shared_ptr<IndexType> ind) :
-	mOp(op),
-	mInd(ind) {}
+    template <class CXpr>
+    Contraction<CXpr>::Contraction(CXpr&& cxpr) :
+	mCXpr(cxpr)
+    {}
 
-    // forward loop !!!!
-    template <typename T, class Op, class IndexType>
-    template <class ET>
-    inline auto Contraction<T,Op,IndexType>::get(ET pos) const
-        -> decltype(mOp.template get<ET>(pos))
+    template <class CXpr>
+    template <class PosT>
+    constexpr decltype(auto) Contraction<CXpr>::get(const PosT& pos) const
     {
-	return mOp.template get<ET>(pos);
+	return mCXpr(pos);
     }
 
-    template <typename T, class Op, class IndexType>
-    template <typename V, class ET>
-    inline auto Contraction<T,Op,IndexType>::vget(ET pos) const
-        -> decltype(mOp.template vget<V,ET>(pos))
+    template <class CXpr>
+    template <SizeT I>
+    constexpr decltype(auto) Contraction<CXpr>::rootSteps(const IndexId<I>& id) const;
     {
-	return mOp.template vget<V,ET>(pos);
+	return mCXpr.stepSize(id);
     }
 
-    template <typename T, class Op, class IndexType>
-    template <class ET>
-    inline Contraction<T,Op,IndexType>& Contraction<T,Op,IndexType>::set(ET pos)
-    {
-	mOp.set(pos);
-	return *this;
-    }
-
-    template <typename T, class Op, class IndexType>
-    auto Contraction<T,Op,IndexType>::rootSteps(std::intptr_t iPtrNum) const
-	-> decltype(mOp.rootSteps(iPtrNum))
-    {
-	return mOp.rootSteps(iPtrNum);
-    }
-
-    template <typename T, class Op, class IndexType>
+    template <class CXpr>
     template <class Expr>
-    auto Contraction<T,Op,IndexType>::loop(Expr exp) const
-	-> decltype(mInd->iforh(1,mOp.loop(exp)))
+    constexpr decltype(auto) Contraction<CXpr>::loop(Xpr&& xpr) const
     {
-	return mInd->iforh(0,mOp.loop(exp));
+	return xpr;
     }
 
+    template <class F, class Op, class IndexT>
+    constexpr decltype(auto) mkContracion(F&& f, Op&& op, const Sptr<IndexT>& i)
+    {
+	typedef decltype(i->ifor( mkOpXpr( f, op ) )) CXprT;
+	return Contraction<CXprT>( i->ifor( mkOpXpr( f, op ) ) );
+    }
 }
 
 #endif
diff --git a/src/include/operation/op_types.h b/src/include/operation/op_types.h
index 6128170..9b25aab 100644
--- a/src/include/operation/op_types.h
+++ b/src/include/operation/op_types.h
@@ -154,48 +154,30 @@ namespace CNORXZ
 	
     };
     
-    template <typename T, class Op, class IndexType>
-    class Contraction : public OperationTemplate<T,Contraction<T,Op,IndexType> >
+    template <class CXpr>
+    class Contraction : public OpInterface<Contraction<CXpr>>
     {
     public:
+	typedef OpInterface<Contraction<CXpr>> OI;
 
-	typedef T value_type;
-	typedef OperationBase<T,Contraction<T,Op,IndexType> > OT;
+	constexpr Contraction(CXpr&& cxpr);
+
+	template <class PosT>
+	constexpr decltype(auto) get(const PosT& pos) const;
+
+	template <SizeT I>
+	constexpr decltype(auto) rootSteps(const IndexId<I>& id) const;
+
+	template <class Xpr>
+	constexpr decltype(auto) loop(Xpr&& xpr) const;
 
-	static constexpr size_t SIZE = Op::SIZE;
-        static constexpr bool CONT = Op::CONT;
-        static constexpr bool VABLE = Op::VABLE;
-        
     private:
-
-	Op mOp;
-	std::shared_ptr<IndexType> mInd;
-
-    public:
-	typedef decltype(mOp.rootSteps(0)) ETuple;
-	
-	Contraction(const Op& op, std::shared_ptr<IndexType> ind);
-
-	template <class ET>
-	inline auto get(ET pos) const
-            -> decltype(mOp.template get<ET>(pos));
-
-	template <typename V, class ET>
-	inline auto vget(ET pos) const
-            -> decltype(mOp.template vget<V,ET>(pos));
-
-	template <class ET>
-	inline Contraction& set(ET pos);
-
-	T* data() const { assert(0); return nullptr; }
-
-	auto rootSteps(std::intptr_t iPtrNum = 0) const  // nullptr for simple usage with decltype
-	    -> decltype(mOp.rootSteps(iPtrNum));
-
-	template <class Expr>
-	auto loop(Expr exp) const
-	    -> decltype(mInd->iforh(1,mOp.loop(exp)));
+	CXpr mCXpr;
+	Sptr<IndexType> mInd;
     };
+
+    template <class F, class Op, class IndexT>
+    constexpr decltype(auto) mkContracion(F&& f, Op&& op, const Sptr<IndexT>& i);
 }
 
 #endif