diff --git a/nested/src/commander.rs b/nested/src/commander.rs
index d58db3d..2dee032 100644
--- a/nested/src/commander.rs
+++ b/nested/src/commander.rs
@@ -7,12 +7,18 @@ pub trait Commander {
 
 use std::sync::{Arc, RwLock};
 use crate::{
-    type_system::ReprTree
+    type_system::ReprTree,
+    tree::{nav::TreeNavResult, NestedNode}
 };
 
 //use r3vi::view::singleton::*;
 
 pub trait ObjCommander {
+
+    fn send_cmd_node(&mut self, node: NestedNode) -> TreeNavResult {
+        TreeNavResult::Continue
+    }
+
     fn send_cmd_obj(&mut self, cmd_obj: Arc<RwLock<ReprTree>>);
 }
 
@@ -20,7 +26,7 @@ pub trait ObjCommander {
 impl<C: Commander> ObjCommander for C
 where C::Cmd: 'static
 {
-    fn send_cmd_obj(&mut self, cmd_obj: Arc<RwLock<ReprTree>>) {
+    fn send_cmd_obj(&mut self, _cmd_obj: Arc<RwLock<ReprTree>>) {
         /*
         self.send_cmd(
             &cmd_obj.read().unwrap()
diff --git a/nested/src/editors/char/mod.rs b/nested/src/editors/char/mod.rs
index c4d9374..e77175a 100644
--- a/nested/src/editors/char/mod.rs
+++ b/nested/src/editors/char/mod.rs
@@ -8,13 +8,12 @@ use {
     },
     crate::{
         type_system::{Context, ReprTree},
-        terminal::{TerminalAtom, TerminalEvent, TerminalStyle},
+        terminal::{TerminalAtom, TerminalStyle},
         tree::NestedNode,
         commander::{ObjCommander}
     },
     std::sync::Arc,
-    std::sync::RwLock,
-    termion::event::{Event, Key}
+    std::sync::RwLock
 };
 
 pub struct CharEditor {
@@ -24,13 +23,11 @@ pub struct CharEditor {
 
 impl ObjCommander for CharEditor {
     fn send_cmd_obj(&mut self, cmd_obj: Arc<RwLock<ReprTree>>) {
-        let ctx = self.ctx.read().unwrap();
-
         let cmd_obj = cmd_obj.read().unwrap();
         let cmd_type = cmd_obj.get_type().clone();
 
-        let char_type = ctx.type_term_from_str("( Char )").unwrap();
-        let term_event_type = ctx.type_term_from_str("( TerminalEvent )").unwrap();
+        let char_type = (&self.ctx, "( Char )").into();
+        //let _term_event_type = (&ctx, "( TerminalEvent )").into();
 
         if cmd_type == char_type {
             if let Some(cmd_view) = cmd_obj.get_view::<dyn SingletonView<Item = char>>() {
diff --git a/nested/src/editors/integer/editor.rs b/nested/src/editors/integer/editor.rs
index 1bfe69b..5863557 100644
--- a/nested/src/editors/integer/editor.rs
+++ b/nested/src/editors/integer/editor.rs
@@ -79,7 +79,7 @@ impl DigitEditor {
     pub fn into_node(self, depth: usize) -> NestedNode {
         let data = self.get_data();        
         let editor = Arc::new(RwLock::new(self));
-        let mut ed = editor.write().unwrap();
+        let ed = editor.write().unwrap();
         let r = ed.radix;
 
         NestedNode::new(depth)
@@ -140,7 +140,7 @@ pub struct PosIntEditor {
 
 impl PosIntEditor {
     pub fn new(ctx: Arc<RwLock<Context>>, radix: u32) -> Self {
-        let mut editor = PTYListEditor::new(
+        let editor = PTYListEditor::new(
             ctx.clone(),
             TypeTerm::Type {
                 id: ctx.read().unwrap().get_typeid("Digit").unwrap(),
diff --git a/nested/src/editors/list/editor.rs b/nested/src/editors/list/editor.rs
index cf662b1..1c27977 100644
--- a/nested/src/editors/list/editor.rs
+++ b/nested/src/editors/list/editor.rs
@@ -1,24 +1,14 @@
 use {
     r3vi::{
-        view::{
-            OuterViewPort,
-            singleton::*,
-            sequence::*,
-        },
-        buffer::{
-            singleton::*,
-            vec::*,
-        }
+        view::{OuterViewPort, singleton::*, sequence::*},
+        buffer::{singleton::*, vec::*}
     },
     crate::{
         type_system::{Context, TypeTerm, ReprTree},
-        editors::list::{
-            ListCursor,
-            ListCursorMode
-        },
+        editors::list::{ListCursor, ListCursorMode},
         tree::{NestedNode, TreeNav}
     },
-    std::sync::{Arc, RwLock},
+    std::sync::{Arc, RwLock}
 };
 
 //<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
@@ -246,7 +236,7 @@ impl ListEditor {
             self.cursor.set(cur);
         }
     }
-    
+
     /// split the list off at the current cursor position and return the second half
     pub fn split(&mut self) -> ListEditor {
         let mut le = ListEditor::new(self.ctx.clone(), self.typ.clone());
@@ -258,6 +248,35 @@ impl ListEditor {
                 le.data.push( self.data.get(idx) );
                 self.data.remove(idx);
             }
+
+            if self.is_listlist() {
+                if idx > 0 && idx < self.data.len() {
+                    let prev_idx = idx - 1;
+                    let prev_node = self.data.get(prev_idx);
+
+                    if let Some(prev_editor) = prev_node.editor.clone() {
+                        eprintln!("prev prev editor");
+                        let mut prev_editor = prev_editor.downcast::<RwLock<ListEditor>>().unwrap();
+                        let mut prev_editor = prev_editor.write().unwrap();
+                        if prev_editor.get_data_port().get_view().unwrap()
+                            .iter().filter(
+                                |x|
+                                /*
+                                if let Some(data) = x.data.clone() {
+                                    let data = data.;
+                                    data.read().unwrap().is_some()
+                                } else {
+                                    false
+                            }
+                                */ true
+                            ).count() == 0
+                        {
+                            drop(prev_editor);
+                            self.data.remove(prev_idx);
+                        }
+                    }
+                }
+            }
         }
 
         le
diff --git a/nested/src/editors/list/pty_editor.rs b/nested/src/editors/list/pty_editor.rs
index 9871520..8a21fe2 100644
--- a/nested/src/editors/list/pty_editor.rs
+++ b/nested/src/editors/list/pty_editor.rs
@@ -1,23 +1,12 @@
 use {
     r3vi::{
-        view::{
-            OuterViewPort,
-            sequence::*,
-        },
+        view::{OuterViewPort, sequence::*},
         projection::decorate_sequence::*,
     },
     crate::{
         type_system::{Context, TypeTerm, ReprTree},
-        editors::list::{
-            ListCursor, ListCursorMode,
-            segment::{ListSegmentSequence},
-            editor::ListEditor
-        },
-        terminal::{
-            TerminalEvent,
-            TerminalView,
-            make_label
-        },
+        editors::list::*,
+        terminal::{TerminalEvent, TerminalView, make_label},
         tree::{TreeCursor, TreeNav},
         diagnostics::{Diagnostics},
         tree::NestedNode,
@@ -274,11 +263,21 @@ impl ObjCommander for PTYListEditor {
                                             e.delete_nexd();
                                         }
                                         _ => {
-                                            let mut new_edit = Context::make_node(&e.ctx, e.typ.clone(), self.depth).unwrap();
-                                            new_edit.goto(TreeCursor::home());
-                                            new_edit.send_cmd_obj(cmd_obj);
+                                            let mut node = Context::make_node(&e.ctx, e.typ.clone(), self.depth).unwrap();
+                                            node.goto(TreeCursor::home());
+                                            node.send_cmd_obj(cmd_obj);
+/*
+                                            if e.is_listlist() {
+                                                if let Some(new_edit) = node.get_edit::<ListEditor>() {
+                                                    if new_edit.data.len() == 0 {
+                                                        remove = true;
+                                                    }
+                                                }
+                                            }
 
-                                            e.insert(new_edit);
+                                            if ! remove {
+                                            */
+                                            e.insert(node);
                                         }
                                     }
                                 },
@@ -302,7 +301,7 @@ impl ObjCommander for PTYListEditor {
                                                         if item_cur.tree_addr.len() > 1 {
                                                         let mut item = e.get_item_mut().unwrap();
                                                         item.handle_terminal_event(event);
-                                                    }
+                                                        }
                                                          */
                                                     } else {
                                                         item.send_cmd_obj(cmd_obj);
diff --git a/nested/src/editors/product/editor.rs b/nested/src/editors/product/editor.rs
index 64ab5c6..ef9d88d 100644
--- a/nested/src/editors/product/editor.rs
+++ b/nested/src/editors/product/editor.rs
@@ -185,75 +185,84 @@ impl ProductEditor {
             self.update_segment(c);
         }
     }
-}
 
-use crate::commander::Commander;
-impl Commander for ProductEditor {
-    type Cmd = TerminalEvent;
-
-    fn send_cmd(&mut self, ev: &TerminalEvent) {
-        self.handle_terminal_event(ev);
-    }
-}
-
-impl TerminalEditor for ProductEditor {
-    fn get_term_view(&self) -> OuterViewPort<dyn TerminalView> {
+    pub fn get_term_view(&self) -> OuterViewPort<dyn TerminalView> {
         let ctx = self.ctx.clone();
         self.segments
             .get_port()
             .map_item(move |_pos, e: &ProductEditorSegment| { e.get_view(ctx.clone()) })
             .flatten()
     }
+}
 
-    fn handle_terminal_event(&mut self, event: &TerminalEvent) -> TerminalEditorResult {
-        let mut update_segment = false;
+use r3vi::view::singleton::SingletonView;
+use crate::{commander::ObjCommander, type_system::ReprTree};
 
-        let result = if let Some(mut segment) = self.get_cur_segment_mut().as_deref_mut() {
-            if let Some(ProductEditorSegment::N{ t, editor, ed_depth, cur_depth, cur_dist: _ }) = segment.deref_mut() {
-                *cur_depth = self.get_cursor().tree_addr.len();
+impl ObjCommander for ProductEditor {
+    fn send_cmd_obj(&mut self, cmd_obj: Arc<RwLock<ReprTree>>) {
+        let co = cmd_obj.read().unwrap();
+        let cmd_type = co.get_type().clone();
+        let term_event_type = (&self.ctx, "( TerminalEvent )").into();
 
-                if let Some(mut e) = editor.clone() {
-                    match e.handle_terminal_event(event) {
-                        TerminalEditorResult::Exit =>
-                            match event {
-                                TerminalEvent::Input(Event::Key(Key::Backspace)) => {
-                                    *editor = None;
-                                    update_segment = true;
+        if cmd_type == term_event_type {
+            if let Some(te_view) = co.get_view::<dyn SingletonView<Item = TerminalEvent>>() {
+                drop(co);
+                let event = te_view.get();
+
+                let mut update_segment = false;
+
+                let result = if let Some(mut segment) = self.get_cur_segment_mut().as_deref_mut() {
+                    if let Some(ProductEditorSegment::N{ t, editor, ed_depth, cur_depth, cur_dist: _ }) = segment.deref_mut() {
+                        *cur_depth = self.get_cursor().tree_addr.len();
+
+                        if let Some(mut e) = editor.clone() {
+                            match e.handle_terminal_event(&event) {
+                                TerminalEditorResult::Exit =>
+                                    match event {
+                                        TerminalEvent::Input(Event::Key(Key::Backspace)) => {
+                                            *editor = None;
+                                            update_segment = true;
+                                            TerminalEditorResult::Continue
+                                        }
+                                        _ => {
+                                            *cur_depth = e.get_cursor().tree_addr.len();
+                                            match self.nexd() {
+                                                TreeNavResult::Continue => TerminalEditorResult::Continue,
+                                                TreeNavResult::Exit => TerminalEditorResult::Exit
+                                            }
+                                        }
+                                    },
+                                TerminalEditorResult::Continue => {
+                                    *cur_depth = e.get_cursor().tree_addr.len();
                                     TerminalEditorResult::Continue
                                 }
-                                _ => {
-                                    *cur_depth = e.get_cursor().tree_addr.len();
-                                    match self.nexd() {
-                                        TreeNavResult::Continue => TerminalEditorResult::Continue,
-                                        TreeNavResult::Exit => TerminalEditorResult::Exit
-                                    }
-                                }
-                            },
-                        TerminalEditorResult::Continue => {
-                            *cur_depth = e.get_cursor().tree_addr.len();
-                            TerminalEditorResult::Continue
+                            }
+                        } else {
+                            let mut e = Context::make_node(&self.ctx, t[0].clone(), *ed_depth+1).unwrap();
+                            *editor = Some(e.clone());
+                            update_segment = true;
+
+                            e.dn();
+                            let x = e.handle_terminal_event(&event);
+                            x
                         }
+                    } else {
+                        unreachable!();
                     }
                 } else {
-                    let mut e = Context::make_node(&self.ctx, t[0].clone(), *ed_depth+1).unwrap();
-                    *editor = Some(e.clone());
-                    update_segment = true;
+                    TerminalEditorResult::Exit
+                };
 
-                    e.dn();
-                    let x = e.handle_terminal_event(event);
-                    x
+                if update_segment {
+                    self.update_cur_segment();
                 }
-            } else {
-                unreachable!();
             }
         } else {
-            TerminalEditorResult::Exit
-        };
-
-        if update_segment {
-            self.update_cur_segment();
+            drop(co);
+            if let Some(mut node) = self.get_cur_editor() {
+                node.send_cmd_obj(cmd_obj);
+            }
         }
-        result
     }
 }
 
diff --git a/nested/src/editors/product/nav.rs b/nested/src/editors/product/nav.rs
index 89354d2..7747715 100644
--- a/nested/src/editors/product/nav.rs
+++ b/nested/src/editors/product/nav.rs
@@ -172,7 +172,7 @@ impl TreeNav for ProductEditor {
                 let nav_result =
                     if let Some(mut element) = self.get_cur_segment_mut() {
                         if let Some(ProductEditorSegment::N{ t: _, editor, ed_depth: _, cur_depth, cur_dist:_ }) = element.deref_mut() {
-                            if let Some(mut e) = editor.as_mut() {
+                            if let Some(e) = editor.as_mut() {
                                 //\\//\\//\\//\\
                                 // horizontal //
                                 //\\//\\//\\//\\
diff --git a/nested/src/editors/sum/editor.rs b/nested/src/editors/sum/editor.rs
index 51574c4..86f49ac 100644
--- a/nested/src/editors/sum/editor.rs
+++ b/nested/src/editors/sum/editor.rs
@@ -2,6 +2,7 @@ use {
     r3vi::{
         view::{
             ViewPort, OuterViewPort,
+            singleton::*,
             sequence::*,            
         }
     },
@@ -10,11 +11,12 @@ use {
             TerminalEditor, TerminalEditorResult,
             TerminalEvent, TerminalView
         },
-        type_system::{Context},
+        editors::list::ListCursorMode,
+        type_system::{Context, ReprTree},
         tree::{TreeNav, TreeCursor, TreeNavResult},
         diagnostics::{Diagnostics, Message},
         tree::NestedNode,
-        commander::Commander,
+        commander::{ObjCommander},
         PtySegment
     },
     cgmath::{Vector2},
@@ -26,6 +28,9 @@ pub struct SumEditor {
     cur: usize,
     pub editors: Vec< NestedNode >,
 
+    addr_port: ViewPort< dyn SequenceView<Item = isize> >,
+    mode_port: ViewPort< dyn SingletonView<Item = ListCursorMode> >,
+
     port: ViewPort< dyn TerminalView >,
     diag_port: ViewPort< dyn SequenceView<Item = Message> >
 }
@@ -40,7 +45,11 @@ impl SumEditor {
             cur: 0,
             editors,
             port,
-            diag_port: ViewPort::new()
+            diag_port: ViewPort::new(),
+
+
+            addr_port: ViewPort::new(),
+            mode_port: ViewPort::new()
         }
     }
 
@@ -50,6 +59,7 @@ impl SumEditor {
         NestedNode::new(0)
             .set_ctx(ctx)
             .set_view(view)
+            .set_editor(editor.clone())
             .set_cmd(editor.clone())
             .set_nav(editor.clone())
 //            .set_diag(editor.read().unwrap().diag.clone())
@@ -62,7 +72,7 @@ impl SumEditor {
     pub fn select(&mut self, idx: usize) {
         self.cur = idx;
 
-        let tv = self.editors[ self.cur ].get_term_view();
+        let tv = self.editors[ self.cur ].get_view();
         tv.add_observer( self.port.get_cast() );
         self.port.update_hooks.write().unwrap().clear();
         self.port.add_update_hook( Arc::new(tv.0.clone()) );
@@ -73,6 +83,18 @@ impl SumEditor {
         self.diag_port.update_hooks.write().unwrap().clear();
         self.diag_port.add_update_hook( Arc::new(dv.0.clone()) );
         self.diag_port.set_view( Some(dv.get_view_arc()) );
+
+        let dv = self.editors[ self.cur ].get_addr_view();
+        dv.add_observer( self.addr_port.get_cast() );
+        self.addr_port.update_hooks.write().unwrap().clear();
+        self.addr_port.add_update_hook( Arc::new(dv.0.clone()) );
+        self.addr_port.set_view( Some(dv.get_view_arc()) );
+        
+        let dv = self.editors[ self.cur ].get_mode_view();
+        dv.add_observer( self.mode_port.get_cast() );
+        self.mode_port.update_hooks.write().unwrap().clear();
+        self.mode_port.add_update_hook( Arc::new(dv.0.clone()) );
+        self.mode_port.set_view( Some(dv.get_view_arc()) );
     }
 }
 
@@ -92,6 +114,14 @@ impl TreeNav for SumEditor {
     fn goto(&mut self, new_cursor: TreeCursor) -> TreeNavResult {
         self.editors[ self.cur ].goto( new_cursor )
     }
+
+    fn get_addr_view(&self) -> OuterViewPort<dyn SequenceView<Item = isize>> {
+        self.addr_port.outer()
+    }
+
+    fn get_mode_view(&self) -> OuterViewPort<dyn SingletonView<Item = ListCursorMode>> {
+        self.mode_port.outer()
+    }
 }
 
 impl PtySegment for SumEditor {
@@ -100,26 +130,8 @@ impl PtySegment for SumEditor {
     }
 }
 
-impl Commander for SumEditor {
-    type Cmd = TerminalEvent;
-
-    fn send_cmd(&mut self, event: &TerminalEvent) {
-        match event {
-            TerminalEvent::Input( termion::event::Event::Key(Key::Ctrl('x')) ) => {
-                let res = self.editors[ self.cur ].handle_terminal_event( event );
-                match res {
-                    TerminalEditorResult::Exit => {
-                        self.select( (self.cur + 1) % self.editors.len() );
-                        if self.editors[ self.cur ].get_cursor().tree_addr.len() == 0 {
-                            self.dn();
-                        }
-                    },
-                    _ => {}
-                }
-            },
-            event => {
-                self.editors[ self.cur ].handle_terminal_event( event );
-            }
-        }
+impl ObjCommander for SumEditor {
+    fn send_cmd_obj(&mut self, obj: Arc<RwLock<ReprTree>>) {
+        self.editors[ self.cur ].send_cmd_obj( obj );
     }
 }
diff --git a/nested/src/tree/node.rs b/nested/src/tree/node.rs
index 697adaa..55377d7 100644
--- a/nested/src/tree/node.rs
+++ b/nested/src/tree/node.rs
@@ -1,17 +1,13 @@
 use {
     std::{sync::{Arc, RwLock}, any::Any},
-    cgmath::Vector2,
+    cgmath::{Vector2, Point2},
     r3vi::{
-        view::{
-            ViewPort, OuterViewPort, AnyOuterViewPort,
-            singleton::*,
-            sequence::*
-        },
+        view::{View, ViewPort, OuterViewPort, AnyOuterViewPort, singleton::*, sequence::*},
         buffer::{singleton::*}
     },
     crate::{
         type_system::{ReprTree, Context, TypeTerm},
-        terminal::{TerminalView, TerminalEvent, TerminalEditor, TerminalEditorResult},
+        terminal::{TerminalView, TerminalEvent, TerminalEditor, TerminalEditorResult, TerminalAtom},
         diagnostics::{Diagnostics, Message},
         tree::{TreeNav, TreeCursor, TreeNavResult},
         editors::list::{ListCursorMode},
@@ -101,7 +97,7 @@ impl TreeNav for NestedNode {
             tn.read().unwrap().get_addr_view()
         } else {
             OuterViewPort::default()
-        }        
+        }
     }
 
     fn get_mode_view(&self) -> OuterViewPort<dyn SingletonView<Item = ListCursorMode>> {
@@ -161,6 +157,31 @@ impl NestedNode {
         }
     }
 
+    pub fn from_char(ctx: Arc<RwLock<Context>>, c: char) -> NestedNode {
+        let buf = r3vi::buffer::singleton::SingletonBuffer::<char>::new(c);
+
+        NestedNode::new(0)
+            .set_view(buf.get_port()
+                      .map(|c| TerminalAtom::from(c))
+                      .to_index()
+                      .map_key(
+                          |x| {
+                              Point2::new(0, 0)
+                          },
+                          |p| {
+                              if *p == Point2::new(0,0) { Some(()) } else { None }
+                          })
+            )
+            .set_data(
+                ReprTree::new_leaf(
+                    (&ctx, "( Char )"),
+                    buf.get_port().into()
+                )
+            )
+            .set_editor(Arc::new(RwLock::new(buf)))
+            .set_ctx(ctx)
+    }
+
     pub fn set_ctx(mut self, ctx: Arc<RwLock<Context>>) -> Self {
         self.ctx = Some(ctx);
         self
@@ -207,5 +228,36 @@ impl NestedNode {
     pub fn morph(self, ty: TypeTerm) -> NestedNode {
         Context::morph_node(self, ty)
     }
+
+    pub fn get_data_view<'a, V: View + ?Sized + 'static>(&'a self, type_str: impl Iterator<Item = &'a str>) -> Option<Arc<V>>
+    where V::Msg: Clone {
+        if let Some(ctx) = self.ctx.clone() {
+            if let Some(data) = self.data.clone() {
+                let type_ladder = type_str.map(|s| ((&ctx, s)).into());
+
+                let repr_tree = ReprTree::descend_ladder(&data, type_ladder)?;
+                repr_tree.clone().read().unwrap()
+                    .get_view::<V>().clone()
+            } else {
+                eprintln!("get_data(): no data port");
+                None
+            }
+        } else {
+            eprintln!("get_data(): no ctx");
+            None
+        }
+    }
+
+    pub fn get_edit<T: Send + Sync + 'static>(&self) -> Option<Arc<RwLock<T>>> {
+        if let Some(edit) = self.editor.clone() {
+            if let Ok(edit) = edit.downcast::<RwLock<T>>() {
+                Some(edit)
+            } else {
+                None
+            }
+        } else {
+            None
+        }
+    }
 }
 
diff --git a/nested/src/type_system/context.rs b/nested/src/type_system/context.rs
index 90ce78e..c8300d8 100644
--- a/nested/src/type_system/context.rs
+++ b/nested/src/type_system/context.rs
@@ -42,14 +42,18 @@ pub struct MorphismType {
 
 #[derive(Hash, Eq, PartialEq, Debug)]
 pub struct MorphismTypePattern {
-    pub src_type: Option<TypeTerm>,
+    pub src_tyid: Option<TypeID>,
     pub dst_tyid: TypeID
 }
 
 impl From<MorphismType> for MorphismTypePattern {
     fn from(value: MorphismType) -> MorphismTypePattern {
         MorphismTypePattern {
-            src_type: value.src_type,
+            src_tyid: match value.src_type {
+                Some(TypeTerm::Type { id, args: _ }) => Some(id),
+                _ => None,
+            },
+
             dst_tyid: match value.dst_type {
                 TypeTerm::Type { id, args: _ } => id,
                 _ => unreachable!()
@@ -84,6 +88,12 @@ pub struct Context {
     parent: Option<Arc<RwLock<Context>>>,
 }
 
+impl Into<TypeTerm> for (&Arc<RwLock<Context>>, &str) {
+    fn into(self) -> TypeTerm {
+        self.0.read().unwrap().type_term_from_str(self.1).unwrap()
+    }
+}
+
 impl Context {
     pub fn with_parent(parent: Option<Arc<RwLock<Context>>>) -> Self {
         Context {
@@ -154,7 +164,7 @@ impl Context {
             };
 
         let morphism_pattern = MorphismTypePattern {
-            src_type: None,
+            src_tyid: None,
             dst_tyid: tyid
         };
 
diff --git a/nested/src/type_system/make_editor.rs b/nested/src/type_system/make_editor.rs
index 317e30b..dda3555 100644
--- a/nested/src/type_system/make_editor.rs
+++ b/nested/src/type_system/make_editor.rs
@@ -5,13 +5,12 @@ use {
             char::*,
             list::*,
             integer::*,
-            product::*,
-            sum::*
+            product::*
         },
         tree::{NestedNode},        
         terminal::{TerminalEditor},
         diagnostics::{Diagnostics},
-        type_system::{TypeTermEditor, MorphismTypePattern},
+        type_system::{MorphismTypePattern},
     },
     std::sync::{Arc, RwLock},
     cgmath::Point2
@@ -28,7 +27,7 @@ pub fn init_mem_ctx(parent: Arc<RwLock<Context>>) -> Arc<RwLock<Context>> {
                         id: _, args
                     } => {
                         if args.len() > 0 {
-                            let mut buf = r3vi::buffer::vec::VecBuffer::<char>::new();
+                            let buf = r3vi::buffer::vec::VecBuffer::<char>::new();
                             let data = ReprTree::new_leaf(
                                 ctx.read().unwrap().type_term_from_str("( Char )").unwrap(),
                                 buf.get_port().into()
@@ -105,7 +104,7 @@ pub fn init_editor_ctx(parent: Arc<RwLock<Context>>) -> Arc<RwLock<Context>> {
 
     ctx.write().unwrap().add_list_typename("Symbol".into());
     let pattern = MorphismTypePattern {
-        src_type: ctx.read().unwrap().type_term_from_str("( List Char )"),
+        src_tyid: ctx.read().unwrap().get_typeid("List"),
         dst_tyid: ctx.read().unwrap().get_typeid("Symbol").unwrap()
     };
     ctx.write().unwrap().add_morphism(pattern,
@@ -151,7 +150,7 @@ pub fn init_editor_ctx(parent: Arc<RwLock<Context>>) -> Arc<RwLock<Context>> {
 
     ctx.write().unwrap().add_list_typename("String".into());
     let pattern = MorphismTypePattern {
-        src_type: ctx.read().unwrap().type_term_from_str("( List Char )"),
+        src_tyid: ctx.read().unwrap().get_typeid("List"),
         dst_tyid: ctx.read().unwrap().get_typeid("String").unwrap()
     };
     ctx.write().unwrap().add_morphism(pattern,
@@ -196,7 +195,7 @@ pub fn init_editor_ctx(parent: Arc<RwLock<Context>>) -> Arc<RwLock<Context>> {
             }
         )
     );
-
+/*
     ctx.write().unwrap().add_list_typename("TypeTerm".into());
     ctx.write().unwrap().add_node_ctor(
         "TypeTerm", Arc::new(
@@ -205,7 +204,7 @@ pub fn init_editor_ctx(parent: Arc<RwLock<Context>>) -> Arc<RwLock<Context>> {
             }
         )
     );
-
+*/
     ctx.write().unwrap().add_typename("TerminalEvent".into());
     ctx
 }
@@ -246,7 +245,7 @@ pub fn init_math_ctx(parent: Arc<RwLock<Context>>) -> Arc<RwLock<Context>> {
 
     ctx.write().unwrap().add_list_typename("PosInt".into());
     let pattern = MorphismTypePattern {
-        src_type: ctx.read().unwrap().type_term_from_str("( List ( Digit 10 ) )"),
+        src_tyid: ctx.read().unwrap().get_typeid("List"),
         dst_tyid: ctx.read().unwrap().get_typeid("PosInt").unwrap()
     };
     ctx.write().unwrap().add_morphism(pattern,
@@ -255,13 +254,15 @@ pub fn init_math_ctx(parent: Arc<RwLock<Context>>) -> Arc<RwLock<Context>> {
                 let depth = node.depth;
                 let editor = node.editor.clone().unwrap().downcast::<RwLock<ListEditor>>().unwrap();
 
+                // todo: check src_type parameter to be ( Digit radix )
+                
                 match dst_type {
                     TypeTerm::Type {
                         id: _, args
                     } => {
                         if args.len() > 0 {
                             match args[0] {
-                                TypeTerm::Num(radix) => {
+                                TypeTerm::Num(_radix) => {
                                     let pty_editor = PTYListEditor::from_editor(
                                         editor,
                                         Some(','),
diff --git a/nested/src/type_system/mod.rs b/nested/src/type_system/mod.rs
index 2db9051..a4c590a 100644
--- a/nested/src/type_system/mod.rs
+++ b/nested/src/type_system/mod.rs
@@ -3,13 +3,13 @@ pub mod type_term;
 pub mod repr_tree;
 pub mod context;
 pub mod make_editor;
-pub mod type_term_editor;
+//pub mod type_term_editor;
 
 pub use {
     repr_tree::{ReprTree},
     type_term::{TypeDict, TypeID, TypeTerm, TypeLadder},
     context::{Context, MorphismMode, MorphismType, MorphismTypePattern},
-    type_term_editor::TypeTermEditor,
+//    type_term_editor::TypeTermEditor,
     make_editor::*
 };
 
diff --git a/nested/src/type_system/repr_tree.rs b/nested/src/type_system/repr_tree.rs
index e551c9b..7fa3a1c 100644
--- a/nested/src/type_system/repr_tree.rs
+++ b/nested/src/type_system/repr_tree.rs
@@ -19,9 +19,9 @@ pub struct ReprTree {
 }
 
 impl ReprTree {
-    pub fn new(type_tag: TypeTerm) -> Self {
+    pub fn new(type_tag: impl Into<TypeTerm>) -> Self {
         ReprTree {
-            type_tag,
+            type_tag: type_tag.into(),
             port: None,
             branches: HashMap::new(),
         }
@@ -31,8 +31,8 @@ impl ReprTree {
         &self.type_tag
     }
 
-    pub fn new_leaf(type_tag: TypeTerm, port: AnyOuterViewPort) -> Arc<RwLock<Self>> {
-        let mut tree = ReprTree::new(type_tag);
+    pub fn new_leaf(type_tag: impl Into<TypeTerm>, port: AnyOuterViewPort) -> Arc<RwLock<Self>> {
+        let mut tree = ReprTree::new(type_tag.into());
         tree.insert_leaf(vec![].into_iter(), port);
         Arc::new(RwLock::new(tree))
     }
@@ -82,18 +82,22 @@ impl ReprTree {
                 .get_view()
     }
 
-    pub fn descend(&self, dst_type: &TypeTerm) -> Option<Arc<RwLock<ReprTree>>> {
-        self.branches.get(dst_type).cloned()
+    pub fn descend(&self, dst_type: impl Into<TypeTerm>) -> Option<Arc<RwLock<ReprTree>>> {
+        self.branches.get(&dst_type.into()).cloned()
     }
 
-    pub fn descend_ladder(&self, mut repr_ladder: impl Iterator<Item = TypeTerm>) -> Option<Arc<RwLock<ReprTree>>> {
-        let first = repr_ladder.next()?;
-        repr_ladder.fold(
-            self.descend(&first),
-            |s, t| s?.read().unwrap().descend(&t))
+    pub fn descend_ladder(rt: &Arc<RwLock<Self>>, mut repr_ladder: impl Iterator<Item = TypeTerm>) -> Option<Arc<RwLock<ReprTree>>> {
+        if let Some(first) = repr_ladder.next() {
+            let rt = rt.read().unwrap();
+            repr_ladder.fold(
+                rt.descend(first),
+                |s, t| s?.read().unwrap().descend(t))
+        } else {
+            Some(rt.clone())
+        }
     }
 
-    pub fn ascend(rt: &Arc<RwLock<Self>>, type_term: TypeTerm) -> Arc<RwLock<ReprTree>> {
+    pub fn ascend(rt: &Arc<RwLock<Self>>, type_term: impl Into<TypeTerm>) -> Arc<RwLock<ReprTree>> {
         let mut n = Self::new(type_term);
         n.insert_branch(rt.clone());
         Arc::new(RwLock::new(n))
diff --git a/nested/src/type_system/type_term.rs b/nested/src/type_system/type_term.rs
index de2281d..fb3243e 100644
--- a/nested/src/type_system/type_term.rs
+++ b/nested/src/type_system/type_term.rs
@@ -11,6 +11,7 @@ pub type TypeLadder = Vec<TypeTerm>;
 pub enum TypeTerm {
     Type { id: TypeID, args: Vec<TypeTerm> },
     Num(i64),
+//    Var(u64),
 }
 
 impl TypeTerm {
diff --git a/nested/src/type_system/type_term_editor.rs b/nested/src/type_system/type_term_editor.rs
index 775d62e..19a385d 100644
--- a/nested/src/type_system/type_term_editor.rs
+++ b/nested/src/type_system/type_term_editor.rs
@@ -2,9 +2,7 @@ use {
     crate::{
         type_system::{Context},
         terminal::{TerminalEvent},
-        editors::{
-            sum::*,
-        },
+        editors::{sum::*},
         tree::{TreeNav},
         tree::NestedNode,
         commander::Commander,
@@ -37,9 +35,9 @@ impl TypeTermEditor {
             ty: TypeTermVar::Any,
             sum_edit: Arc::new(RwLock::new(SumEditor::new(
                 vec![
-                    Context::make_node( &ctx, ctx.read().unwrap().type_term_from_str("( List TypeTerm )").unwrap(), depth + 1).unwrap(),
-                    Context::make_node( &ctx, ctx.read().unwrap().type_term_from_str("( PosInt 10 )").unwrap(), depth + 1 ).unwrap(),
-                    Context::make_node( &ctx, ctx.read().unwrap().type_term_from_str("( Symbol )").unwrap(), depth + 1 ).unwrap()
+                    Context::make_node( &ctx, (&ctx, "( List TypeTerm )").into(), depth + 1).unwrap(),
+                    Context::make_node( &ctx, (&ctx, "( PosInt 10 )").into(), depth + 1 ).unwrap(),
+                    Context::make_node( &ctx, (&ctx, "( Symbol )").into(), depth + 1 ).unwrap()
                 ])))
         }
     }