diff --git a/ebcl b/ebcl
index 3adfdad..0bc11d3 160000
--- a/ebcl
+++ b/ebcl
@@ -1 +1 @@
-Subproject commit 3adfdadd119f2783877865a8365a29d4b567911f
+Subproject commit 0bc11d32d746f1075a41137adff51819007d5275
diff --git a/main.cc b/main.cc
index cf48638..343cb17 100644
--- a/main.cc
+++ b/main.cc
@@ -54,7 +54,7 @@ void T_Main::mainLoop( )
 {
 	auto& p( Globals::Profiler( ) );
 	while ( !done ) {
-		if ( demo.present( ) ) {
+		if ( demo ) {
 			auto const& dspSize( ImGui::GetIO( ).DisplaySize );
 			if ( prevSize.x != dspSize.x || prevSize.y != dspSize.y ) {
 				stopResize = ResizeDelay;
@@ -67,7 +67,7 @@ void T_Main::mainLoop( )
 				demo.clear( );
 			}
 		}
-		if ( !demo.present( ) ) {
+		if ( !demo ) {
 			initDemo( );
 		}
 
@@ -100,7 +100,7 @@ T_Main::~T_Main( )
 
 void T_Main::initDemo( )
 {
-	assert( !demo.present( ) );
+	assert( !demo );
 	auto const& dspSize( ImGui::GetIO( ).DisplaySize );
 	if ( dspSize.x < 0 || dspSize.y < 0 ) {
 		return;
@@ -108,7 +108,7 @@ void T_Main::initDemo( )
 
 	printf( "init w/ dspsize %dx%d\n" , int( dspSize.x ) , int( dspSize.y ) );
 	demo.setNew( dspSize.x , dspSize.y );
-	if ( ((T_Demo&)demo).initialise( ) ) {
+	if ( demo->initialise( ) ) {
 		Globals::Profiler( ).clear( );
 	} else {
 		demo.clear( );
@@ -155,8 +155,8 @@ void T_Main::handleCapture( )
 		ImGui::SetMouseCursor( ImGuiMouseCursor_Arrow );
 	} else if ( capture ) {
 		ImGui::SetMouseCursor( ImGuiMouseCursor_Move );
-		if ( demo.present( ) ) {
-			demo.target( )->handleDND( mouseMove , ctrl , shift , lmb );
+		if ( demo ) {
+			demo->handleDND( mouseMove , ctrl , shift , lmb );
 		}
 	} else if ( appCanGrab && mb ) {
 		capture = true;
@@ -166,8 +166,8 @@ void T_Main::handleCapture( )
 		ImGui::SetMouseCursor( ImGuiMouseCursor_Move );
 	}
 
-	if ( ( appCanGrab || capture ) && io.MouseWheel && demo.present( ) ) {
-		demo.target( )->handleWheel( io.MouseWheel , ctrl , shift );
+	if ( ( appCanGrab || capture ) && io.MouseWheel && demo ) {
+		demo->handleWheel( io.MouseWheel , ctrl , shift );
 	}
 }
 
@@ -183,25 +183,25 @@ void T_Main::makeUI( )
 	ImGui::Checkbox( "Profiler" ,		&Globals::Profiler( ).uiEnabled( ) );
 	ImGui::Checkbox( "Shaders" ,		&Globals::Shaders( ).uiEnabled( ) );
 
-	if ( demo.present( ) ) {
+	if ( demo ) {
 		ImGui::Separator( );
 		auto& sync( Globals::Sync( ) );
 		const float duration( sync.duration( ) );
 		float time( sync.time( ) );
 		if ( ImGui::SliderFloat( "" , &time , 0 , duration , "%.1fs" ) ) {
 			sync.setTime( time );
-			demo.target( )->playing = demo.target( )->playing && ! sync.finished( );
+			demo->playing = demo->playing && ! sync.finished( );
 		}
 		ImGui::SameLine( );
-		if ( ImGui::Button( demo.target( )->playing ? "Stop" : "Play" ) ) {
-			demo.target( )->playing = !demo.target( )->playing;
+		if ( ImGui::Button( demo->playing ? "Stop" : "Play" ) ) {
+			demo->playing = !demo->playing;
 		}
 	}
 
 	ImGui::End( );
 
-	if ( demo.present( ) && demoCtrl_ ) {
-		demo.target( )->makeUI( );
+	if ( demo && demoCtrl_ ) {
+		demo->makeUI( );
 	}
 
 	Globals::Profiler( ).makeUI( );
@@ -211,9 +211,9 @@ void T_Main::makeUI( )
 
 void T_Main::render( )
 {
-	if ( demo.present( ) ) {
+	if ( demo ) {
 		Globals::Profiler( ).start( "Render" );
-		demo.target( )->render( );
+		demo->render( );
 		glFinish( ); Globals::Profiler( ).end( "Render" );
 
 		Globals::Profiler( ).start( "Debug" );
diff --git a/opast.cc b/opast.cc
index 1f65085..8d98a47 100644
--- a/opast.cc
+++ b/opast.cc
@@ -491,7 +491,7 @@ void T_ParserImpl_::parseFunction(
 	fn->location( ) = fw.location( );
 
 	const auto af( root->addFunction( fn ) );
-	if ( af.dupLocation.present( ) ) {
+	if ( af.dupLocation ) {
 		T_StringBuilder esb( "duplicate " );
 		switch ( fn->type( ) ) {
 			case A_Node::DECL_FN:
@@ -505,7 +505,7 @@ void T_ParserImpl_::parseFunction(
 				break;
 			default: std::abort( );
 		}
-		esb << "; previous declaration: " << *af.dupLocation.target( );
+		esb << "; previous declaration: " << *af.dupLocation;
 		errors.addNew( std::move( esb ) , fw.location( ) );
 	}
 
@@ -527,10 +527,10 @@ void T_ParserImpl_::parseFunctionArguments(
 		}
 
 		const auto rv( function.addArgument( token ) );
-		if ( rv.present( ) ) {
+		if ( rv ) {
 			T_StringBuilder esb;
 			esb << "duplicate argument '" << token.stringValue( )
-				<< "'; previous declaration: " << *rv.target( );
+				<< "'; previous declaration: " << *rv;
 			errors.addNew( std::move( esb ) , token.location( ) );
 		}
 	}
@@ -708,10 +708,9 @@ M_INSTR_( Pipeline )
 			continue;
 		}
 		const auto dup( pipeline.addProgram( tok ) );
-		if ( dup.present( ) ) {
+		if ( dup ) {
 			T_StringBuilder esb;
-			esb << "duplicate program identifier; previous use: "
-				<< *dup.target( );
+			esb << "duplicate program identifier; previous use: " << *dup;
 			errors.addNew( std::move( esb ) , tok.location( ) );
 		}
 	}
diff --git a/parsercheck.cc b/parsercheck.cc
index 6c5a429..98ffe42 100644
--- a/parsercheck.cc
+++ b/parsercheck.cc
@@ -2,6 +2,7 @@
 #include "opast.hh"
 #include <ebcl/Files.hh>
 #include <ebcl/SRDText.hh>
+#include <ebcl/Algorithms.hh>
 
 using namespace ebcl;
 using namespace opast;
@@ -36,148 +37,6 @@ void WriteSRDError(
 /*============================================================================*/
 // FIXME TESTING, MOVE THIS LATER
 
-template<
-	typename Enum ,
-	typename Storage = uint32_t
-> class T_Flags
-{
-    private:
-	Storage flags_;
-
-    public:
-	constexpr T_Flags( ) noexcept
-		: flags_( 0 ) {}
-
-	constexpr T_Flags( T_Flags const& other ) noexcept
-		: flags_( other.flags_ ) { }
-
-	constexpr T_Flags( const Enum flag ) noexcept
-		: flags_( 1 << int( flag ) ) {}
-
-	constexpr T_Flags( std::initializer_list< Enum > flags ) noexcept
-		: flags_( 0 )
-	{
-		for ( auto f : flags ) {
-			flags_ |= ( 1 << int( f ) );
-		}
-	}
-
-	explicit constexpr T_Flags( const Storage flags ) noexcept
-		: flags_( flags ) { }
-
-	constexpr T_Flags operator |=( T_Flags other ) noexcept
-		{ flags_ |= other.flags_; return *this; }
-	constexpr T_Flags operator &=( T_Flags other ) noexcept
-		{ flags_ &= other.flags_; return *this; }
-	constexpr T_Flags operator ^=( T_Flags other ) noexcept
-		{ flags_ ^= other.flags_; return *this; }
-
-	constexpr T_Flags operator ~( ) const noexcept
-		{ return T_Flags( ~flags_ ); }
-	constexpr T_Flags operator &( T_Flags other ) const noexcept
-		{ return T_Flags( flags_ & other.flags_ ); }
-	constexpr T_Flags operator |( T_Flags other ) const noexcept
-		{ return T_Flags( flags_ & other.flags_ ); }
-	constexpr T_Flags operator ^( T_Flags other ) const noexcept
-		{ return T_Flags( flags_ ^ other.flags_ ); }
-
-	constexpr operator bool( ) const noexcept
-		{ return flags_ != 0; }
-	constexpr bool operator!( ) const noexcept
-		{ return flags_ == 0; }
-	explicit constexpr operator Storage( ) const noexcept
-		{ return flags_; }
-
-	constexpr bool operator ==( const T_Flags other ) const noexcept
-		{ return flags_ == other.flags_; }
-	constexpr bool operator !=( const T_Flags other ) const noexcept
-		{ return flags_ != other.flags_; }
-
-	constexpr bool isSet( const T_Flags value ) const noexcept
-		{ return ( *this & value ) == value; }
-	constexpr bool isClear( const T_Flags value ) const noexcept
-		{ return !( *this & value ); }
-};
-
-
-template< typename NodeType >
-class T_Visitor
-{
-    public:
-	using T_Node = NodeType;
-
-	// Node browser. Returns the Nth child of the specified node, or null
-	// if there are no children left.
-	using F_NodeBrowser = std::function< T_Node*( T_Node& , uint32_t ) >;
-
-	// Node action. Second parameter indicates whether the action is
-	// being called before (false) or after (true) visiting the children.
-	using F_NodeAction = std::function< bool( T_Node& , bool ) >;
-
-    private:
-	enum E_State_ {
-		BEFORE , CHILDREN , AFTER
-	};
-	struct T_NodeRef_ {
-		T_Node* node;
-		uint32_t child;
-		E_State_ state{ BEFORE };
-
-		explicit T_NodeRef_( T_Node* node )
-			: node( node ) , child( 0 ) {}
-		explicit T_NodeRef_( T_Node* node , uint32_t child )
-			: node( node ) , child( child ) {}
-	};
-
-	F_NodeBrowser nodeBrowser_;
-	T_Array< T_NodeRef_ > stack_;
-
-    public:
-	T_Visitor( ) = delete;
-	T_Visitor( T_Visitor const& ) = default;
-	T_Visitor( T_Visitor&& ) noexcept = default;
-
-	explicit T_Visitor( F_NodeBrowser browser ) noexcept;
-
-	void visit( T_Node& root , F_NodeAction action );
-};
-
-template< typename T >
-inline T_Visitor< T >::T_Visitor(
-		F_NodeBrowser browser ) noexcept
-	: nodeBrowser_( std::move( browser ) )
-{ }
-
-template< typename T >
-inline void T_Visitor< T >::visit(
-		T_Node& root ,
-		F_NodeAction action )
-{
-	stack_.addNew( &root , 0 );
-
-	while ( !stack_.empty( ) ) {
-		auto& n( stack_.last( ) );
-		switch ( n.state ) {
-		    case BEFORE:
-			n.state = action( *n.node , false ) ? CHILDREN : AFTER;
-			break;
-		    case CHILDREN: {
-			T_Node* child( nodeBrowser_( *n.node , n.child ++ ) );
-			if ( child ) {
-				stack_.addNew( child , 0 );
-			} else {
-				n.state = AFTER;
-			}
-			break;
-		    }
-		    case AFTER:
-			action( *n.node , true );
-			stack_.removeLast( );
-			break;
-		}
-	}
-}
-
 A_Node* OpASTBrowser(
 		A_Node& node ,
 		const uint32_t child )
@@ -372,13 +231,13 @@ bool checkCalls( T_RootNode& root )
 		return false;
 	}
 
-	T_Visitor< uint32_t > callGraphVisitor(
-			[&]( uint32_t& v , uint32_t child ) -> uint32_t* {
+	T_Visitor< uint32_t , uint32_t > callGraphVisitor(
+			[&]( uint32_t v , uint32_t child ) -> T_Optional< uint32_t > {
 				const uint32_t nc( calls.sizeOf( v ) );
 				if ( child < nc ) {
-					return &calls.get( v , child );
+					return calls.get( v , child );
 				}
-				return nullptr;
+				return {};
 			} );
 	enum class E_CallInfo_ {
 		INIT_CHECKED , FRAME_CHECKED ,
@@ -387,22 +246,22 @@ bool checkCalls( T_RootNode& root )
 	using T_CallInfo_ = T_Flags< E_CallInfo_ , uint8_t >;
 	T_CallInfo_ callInfo[ calls.size( ) ];
 
-	uint32_t initId( root.functionIndex( "*init*" ) );
-	callGraphVisitor.visit( initId , [&]( uint32_t& id , const bool exit ) -> bool {
-		if ( exit || callInfo[ id ] & E_CallInfo_::INIT_CALLED ) {
-			return false;
-		}
-		callInfo[ id ] |= E_CallInfo_::INIT_CALLED;
-		return true;
-	} );
-	uint32_t frameId( root.functionIndex( "*frame*" ) );
-	callGraphVisitor.visit( frameId , [&]( uint32_t& id , const bool exit ) -> bool {
-		if ( exit || callInfo[ id ] & E_CallInfo_::FRAME_CALLED ) {
-			return false;
-		}
-		callInfo[ id ] |= E_CallInfo_::FRAME_CALLED;
-		return true;
-	} );
+	callGraphVisitor.visit( root.functionIndex( "*init*" ) ,
+		[&]( uint32_t id , const bool exit ) -> bool {
+			if ( exit || callInfo[ id ] & E_CallInfo_::INIT_CALLED ) {
+				return false;
+			}
+			callInfo[ id ] |= E_CallInfo_::INIT_CALLED;
+			return true;
+		} );
+	callGraphVisitor.visit( root.functionIndex( "*frame*" ) ,
+		[&]( uint32_t id , const bool exit ) -> bool {
+			if ( exit || callInfo[ id ] & E_CallInfo_::FRAME_CALLED ) {
+				return false;
+			}
+			callInfo[ id ] |= E_CallInfo_::FRAME_CALLED;
+			return true;
+		} );
 
 	T_StringBuilder sb;
 	for ( auto callerId = 0u ; callerId < calls.size( ) ; callerId ++ ) {
diff --git a/rendertarget.cc b/rendertarget.cc
index 6764463..d40b5ea 100644
--- a/rendertarget.cc
+++ b/rendertarget.cc
@@ -19,7 +19,7 @@ T_RendertargetSetup& T_RendertargetSetup::add(
 T_RendertargetSetup& T_RendertargetSetup::depth(
 		__rw__ T_Texture& texture )
 {
-	assert( !depthAttachment_.present( ) );
+	assert( !depthAttachment_ );
 	checkAttachment( texture , 0 );
 	depthAttachment_.setNew( texture , 0 );
 	return *this;
@@ -65,8 +65,8 @@ T_Rendertarget T_RendertargetSetup::create( )
 				colorAttachments_[ i ].texture->id( ) ,
 				colorAttachments_[ i ].level );
 	}
-	if ( depthAttachment_.present( ) ) {
-		T_Attachment_ const& de( depthAttachment_ );
+	if ( depthAttachment_ ) {
+		T_Attachment_ const& de( *depthAttachment_ );
 		glFramebufferTexture( GL_FRAMEBUFFER ,
 				GL_DEPTH_ATTACHMENT ,
 				de.texture->id( ) ,
diff --git a/shaders.cc b/shaders.cc
index aa22562..75ae0a0 100644
--- a/shaders.cc
+++ b/shaders.cc
@@ -949,8 +949,8 @@ void T_ShaderManager::programUpdated(
 void T_ShaderManager::resetProgram(
 		T_Program_& program )
 {
-	if ( program.watch.present( ) ) {
-		program.watch.clear( );
+	if ( program.watch ) {
+		program.watch->clear( );
 	}
 	if ( program.id != 0 ) {
 		glDeleteProgram( program.id );
diff --git a/sync.cc b/sync.cc
index 9f5b45f..9f872f4 100644
--- a/sync.cc
+++ b/sync.cc
@@ -99,8 +99,8 @@ bool CPSegmentVD_( T_SRDParserData const& data )
 {
 	auto const& input( *data.input );
 	const auto ev( data.config.enumValue( "segment-type" , input[ 1 ].stringValue( ) ) );
-	assert( ev.present( ) );
-	CPHandleSegment_( (T_SyncSegment::E_SegmentType) *ev.target( ) ,
+	assert( ev );
+	CPHandleSegment_( (T_SyncSegment::E_SegmentType) *ev ,
 			input[ 2 ].list( ) , input[ 3 ].list( ) ,
 			data.errors , data.targetData->value< T_SyncCurve >( ) );
 	return true;
@@ -110,8 +110,8 @@ bool CPSegmentDV_( T_SRDParserData const& data )
 {
 	auto const& input( *data.input );
 	const auto ev( data.config.enumValue( "segment-type" , input[ 1 ].stringValue( ) ) );
-	assert( ev.present( ) );
-	CPHandleSegment_( (T_SyncSegment::E_SegmentType) *ev.target( ) ,
+	assert( ev );
+	CPHandleSegment_( (T_SyncSegment::E_SegmentType) *ev ,
 			input[ 3 ].list( ) , input[ 2 ].list( ) ,
 			data.errors , data.targetData->value< T_SyncCurve >( ) );
 	return true;