diff --git a/src/morphism.rs b/src/morphism.rs
index 8cf6a02..4a7d87e 100644
--- a/src/morphism.rs
+++ b/src/morphism.rs
@@ -1,8 +1,6 @@
 use {
     crate::{
-        unification::UnificationProblem, TypeDict, TypeID, TypeTerm,
-        pretty::*,
-        sugar::SugaredTypeTerm,
+        subtype_unify, sugar::SugaredTypeTerm, unification::UnificationProblem, unparser::*, TypeDict, TypeID, TypeTerm
     },
     std::{collections::HashMap, u64}
 };
@@ -135,13 +133,17 @@ impl<M: Morphism + Clone> MorphismBase<M> {
                             ]));
                     }
 
-                    dst_types.push(
-                        MorphismInstance {
-                            halo: TypeTerm::Ladder(dst_halo_ladder).normalize(),
-                            m: item_morph_inst.m.map_morphism(seq_type.clone()).expect("couldnt get map morphism"),
-                            σ: item_morph_inst.σ
-                        }
-                    );
+                    if let Some( map_morph ) = item_morph_inst.m.map_morphism( seq_type.clone() ) {
+                        dst_types.push(
+                            MorphismInstance {
+                                halo: TypeTerm::Ladder(dst_halo_ladder).normalize(),
+                                m: map_morph,
+                                σ: item_morph_inst.σ
+                            }
+                        );
+                    } else {
+                        eprintln!("could not get map morphism");
+                    }
                 }
             }
         }
@@ -245,28 +247,54 @@ impl<M: Morphism + Clone> MorphismBase<M> {
         None
     }
 
-/*
-    pub fn find_direct_morphism(&self, ty: &MorphismType) -> Option< (M, HashMap<TypeID, TypeTerm>) > {
-        for m in self.morphisms.iter() {
-            let unification_problem = UnificationProblem::new(
-                vec![
-                    ( ty.src_type.clone(), m.get_type().src_type.clone() ),
-                    ( m.get_type().dst_type.clone(), ty.dst_type.clone() )
-                ]
-            );
 
-            let unification_result = unification_problem.solve_subtype();
-            if let Ok((halo, σ)) = unification_result {
-                return Some((m.clone(), σ));
+    pub fn find_direct_morphism(&self,
+        ty: &MorphismType,
+        dict: &mut impl TypeDict
+    ) -> Option< MorphismInstance<M> > {
+        eprintln!("find direct morph");
+        for m in self.morphisms.iter() {
+            let ty = ty.clone().normalize();
+            let morph_type = m.get_type().normalize();
+
+            eprintln!("find direct morph:\n   {}  <=   {}",
+                            dict.unparse(&ty.src_type), dict.unparse(&morph_type.src_type),
+                        );
+
+            if let Ok((halo, σ)) = subtype_unify(&ty.src_type, &morph_type.src_type) {
+                eprintln!("halo: {}", dict.unparse(&halo));
+
+                let dst_type = TypeTerm::Ladder(vec![
+                    halo.clone(),
+                    morph_type.dst_type.clone()
+                ]);
+                eprintln!("----------->   {}  <=   {}",
+                    dict.unparse(&dst_type), dict.unparse(&ty.dst_type)
+                );
+
+                /*
+                let unification_problem = UnificationProblem::new(
+                                vec![
+                                    ( ty.src_type, morph_type.src_type ),
+                                    ( morph_type.dst_type, ty.dst_type )
+                                ]
+                            );*/
+
+                if let Ok((halo2, σ2)) = subtype_unify(&dst_type, &ty.dst_type) {
+                    eprintln!("match. halo2 = {}", dict.unparse(&halo2));
+                    return Some(MorphismInstance {
+                        m: m.clone(),
+                        halo: halo2,
+                        σ,
+                    });
+                }
             }
         }
         None
     }
 
-    pub fn find_map_morphism(&self, ty: &MorphismType) -> Option< (M, HashMap<TypeID, TypeTerm>) > {
+    pub fn find_map_morphism(&self, ty: &MorphismType, dict: &mut impl TypeDict) -> Option< MorphismInstance<M> > {
         for seq_type in self.seq_types.iter() {
-            eprintln!("try seq type {:?}", seq_type);
-
             if let Ok((halo, σ)) = UnificationProblem::new(vec![
                 (ty.src_type.clone().param_normalize(),
                     TypeTerm::App(vec![ seq_type.clone(), TypeTerm::TypeID(TypeID::Var(100)) ])),
@@ -281,9 +309,13 @@ impl<M: Morphism + Clone> MorphismBase<M> {
                 }.normalize();
 
                 //eprintln!("Map Morph: try to find item-morph with type {:?}", item_morph_type);
-                if let Some((m, σ)) = self.find_morphism( &item_morph_type ) {
-                    if let Some(list_morph) = m.map_morphism( seq_type.clone() ) {
-                        return Some( (list_morph, σ) );
+                if let Some(item_morph_inst) = self.find_morphism( &item_morph_type, dict ) {
+                    if let Some( list_morph ) = item_morph_inst.m.map_morphism( seq_type.clone() ) {
+                        return Some( MorphismInstance {
+                            m: list_morph,
+                            σ,
+                            halo
+                        } );
                     }
                 }
             }
@@ -292,17 +324,18 @@ impl<M: Morphism + Clone> MorphismBase<M> {
         None
     }
 
-    pub fn find_morphism(&self, ty: &MorphismType)
-    -> Option< ( M, HashMap<TypeID, TypeTerm> ) > {
-        if let Some((m,σ)) = self.find_direct_morphism(ty) {
-            return Some((m,σ));
+    pub fn find_morphism(&self, ty: &MorphismType,
+        dict: &mut impl TypeDict
+    )
+    -> Option< MorphismInstance<M> > {
+        if let Some(m) = self.find_direct_morphism(ty, dict) {
+            return Some(m);
         }
-        if let Some((m,σ)) = self.find_map_morphism(ty) {
-            return Some((m, σ));
+        if let Some(m) = self.find_map_morphism(ty, dict) {
+            return Some(m);
         }
         None
     }
-    */
 }
 
 //<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>\\