ok kinda works?

bidir/src/bidir_debruijn.rs

@@ -203,26 +203,25 @@ pub fn synthesize(ctx: &Context, term: &Term) -> Result<(Type, Context)> {
       let ex_b_2 = ex_b.transform_with_visitor(&V(1, aug_ctx.size()))?;
       let e_2 = e.transform_with_visitor(&V(0, aug_ctx.size()))?;
 
-      println!("---");
       let wtf_ctx = typecheck(&aug_ctx, &e_2, &ex_b_2)?;
 
       let (before_marker, after_marker) = wtf_ctx.split_at(&marker_idx);
 
       // Bump the levels down since we're splitting teh array
-      struct V2(usize);
+      struct V2(usize, usize);
       impl Visitor for V2 {
         fn visit_index(&self, index: &mut ContextIndex) -> Result<()> {
-          index.debruijn_level -= 1;
-          index.debruijn_index = self.0 - 1 - index.debruijn_level;
+          index.debruijn_level -= self.0;
+          index.debruijn_index = self.1 - 1 - index.debruijn_level;
           Ok(())
         }
       }
       let after_marker =
-        after_marker.transform_with_visitor(&V2(after_marker.size()))?;
+        after_marker.transform_with_visitor(&V2(0, after_marker.size()))?;
 
       let tau = Type::Arrow(Box::new(ex_a_2), Box::new(ex_b));
-      println!("pre-tau: {tau:?} (in {after_marker:?})");
       let tau = app_ctx(&after_marker, &tau)?;
+      let tau = tau.transform_with_visitor(&V2(1, after_marker.size()))?;
 
       // let (final_ctx, gen_idx) =
       //   before_marker.add(ContextEntry::ExistentialVar);

bidir/src/data_debruijn.rs

@@ -232,7 +232,11 @@ impl Type {
         Type::Existential(index)
       }
       Type::Polytype(_) => todo!(),
-      Type::Arrow(_, _) => todo!(),
+      Type::Arrow(a, b) => {
+        let a = a.transform_with_visitor(visitor)?;
+        let b = b.transform_with_visitor(visitor)?;
+        Type::Arrow(Box::new(a), Box::new(b))
+      }
       _ => ty,
     };
     visitor.visit_type_after(&mut ty)?;
@@ -348,7 +352,7 @@ pub struct Context {
 
 impl fmt::Debug for Context {
   fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-    write!(f, "ᴦ{:?}", self.vector)
+    write!(f, "Γ{:?}", self.vector)
   }
 }