diff --git a/src/catalog/trie.rs b/src/catalog/trie.rs
index 8f13be8..c0ff28c 100644
--- a/src/catalog/trie.rs
+++ b/src/catalog/trie.rs
@@ -140,6 +140,9 @@ pub trait TrieElim<X>: Debug + Hash + PartialEq + Eq + Clone + 'static {
               NameC: FnOnce(&Name, &Self) -> Res;
 }
 
+/*
+20121221-- requires box_syntax feature
+
 impl<X: Debug + Hash + PartialEq + Eq + Clone + 'static> Trie<X> {
     fn mfn(nm: Name, meta: Meta, trie: Self, bs: BS, elt: X, hash: u64) -> Self {
         match trie {
@@ -214,6 +217,7 @@ impl<X: Debug + Hash + PartialEq + Eq + Clone + 'static> Trie<X> {
         }
     }
 }
+*/
 
 impl<X: Debug + Hash + PartialEq + Eq + Clone + 'static> TrieIntro<X> for Trie<X> {
     fn nil(bs: BS) -> Self {
@@ -262,7 +266,7 @@ impl<X: Debug + Hash + PartialEq + Eq + Clone + 'static> TrieIntro<X> for Trie<X
     fn extend(nm: Name, trie: Self, elt: X) -> Self {
         let (nm, nm_) = name_fork(nm);
         // let a = Self::root_mfn(nm.clone(), nm_, trie, elt);
-        let root_mfn_art = put(Self::root_mfn(nm.clone(), nm_, trie, elt));
+        let root_mfn_art = panic!("todo"); //put(Self::root_mfn(nm.clone(), nm_, trie, elt));
         Self::name(nm, Self::art(root_mfn_art))
     }
 }
diff --git a/src/engine.rs b/src/engine.rs
index d6c9f8b..6e4ce1f 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -33,7 +33,7 @@ thread_local!(static UNIT_NAME: Name = Name{ hash:0, symbol: Rc::new(NameSym::Un
 
 struct TraceSt { stack:Vec<Box<Vec<reflect::trace::Trace>>>, }
 
-/// When this option is set to some, the engine will record a trace of its DCG effects.
+// When this option is set to some, the engine will record a trace of its DCG effects.
 thread_local!(static TRACES: RefCell<Option<TraceSt>> = RefCell::new( None ));
 
 fn my_hash<T>(obj: T) -> u64
@@ -1557,15 +1557,15 @@ impl Adapton for DCG {
                     }} else                 { (false, false, None, true, true ) }
             ;
             // - - - - - - - - - -
-            /// Begin an allocation.  Because this allocation may require
-            /// dirtying some allocation edges. (See value of bit
-            /// `do_dirty`, which is true when we are overwriting what was
-            /// once a computation with a value). This allocation may also
-            /// require dirtying some observers, when the new value is
-            /// different from the one that they last observed. (Similarly,
-            /// allocations that allocated a different value need to be
-            /// dirtied too).  Hence, this effect may contain other effects
-            /// to the DCG, namely, those dirtying steps.
+            // Begin an allocation.  Because this allocation may require
+            // dirtying some allocation edges. (See value of bit
+            // `do_dirty`, which is true when we are overwriting what was
+            // once a computation with a value). This allocation may also
+            // require dirtying some observers, when the new value is
+            // different from the one that they last observed. (Similarly,
+            // allocations that allocated a different value need to be
+            // dirtied too).  Hence, this effect may contain other effects
+            // to the DCG, namely, those dirtying steps.
             // - - - - - - -
             dcg_effect_begin!(
                 reflect::trace::Effect::Alloc(
diff --git a/src/lib.rs b/src/lib.rs
index fa5b26c..2086a98 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1396,8 +1396,8 @@ list.
 */
 
 //#![feature(associated_consts)]
-#![feature(box_patterns)]
-#![feature(box_syntax)]
+//#![feature(box_patterns)]
+//#![feature(box_syntax)]
 
 #![crate_name = "adapton"]
 #![crate_type = "lib"]