diff --git a/Cargo.lock b/Cargo.lock
index 5339e790..9e50ad62 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -222,9 +222,9 @@ checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
 
 [[package]]
 name = "im_ternary_tree"
-version = "0.0.1-a2"
+version = "0.0.1-a3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "047ce6cd3066d45196d7b08e014547b36ab5ad64cd65fe9fa3aab07ddf31b8bf"
+checksum = "ba6dabade3a7b2059ab2557052f8a6c9970d4f5aa4b1aab66a5b38205e0e1870"
 
 [[package]]
 name = "inotify"
diff --git a/Cargo.toml b/Cargo.toml
index 5437e2ec..8a59f47f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -30,7 +30,7 @@ notify = "4.0.17"
 walkdir = "2"
 hex = "0.4.3"
 rpds = "0.10.0"
-im_ternary_tree = "0.0.1-a2"
+im_ternary_tree = "0.0.1-a3"
 # im_ternary_tree = { path = "/Users/chen/repo/calcit-lang/ternary-tree" }
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
diff --git a/src/builtins/syntax.rs b/src/builtins/syntax.rs
index 6d1edd26..7421b53a 100644
--- a/src/builtins/syntax.rs
+++ b/src/builtins/syntax.rs
@@ -303,10 +303,10 @@ pub fn call_try(expr: &CalcitItems, scope: &CalcitScope, file_ns: &str, call_sta
         let err_data = Calcit::Str(failure.msg.to_owned().into_boxed_str());
         match f {
           Calcit::Fn(_, def_ns, _, def_scope, args, body) => {
-            let values = TernaryTreeList::from(&vec![err_data]);
+            let values = TernaryTreeList::from(&[err_data]);
             runner::run_fn(&values, &def_scope, &args, &body, &def_ns, call_stack)
           }
-          Calcit::Proc(proc) => builtins::handle_proc(&proc, &TernaryTreeList::from(&vec![err_data]), call_stack),
+          Calcit::Proc(proc) => builtins::handle_proc(&proc, &TernaryTreeList::from(&[err_data]), call_stack),
           a => CalcitErr::err_str(format!("try expected a function handler, got: {}", a)),
         }
       }
diff --git a/src/runner/preprocess.rs b/src/runner/preprocess.rs
index 8c5c9189..10b758e6 100644
--- a/src/runner/preprocess.rs
+++ b/src/runner/preprocess.rs
@@ -346,7 +346,7 @@ fn process_list_call(
 
     (_, Some(Calcit::Fn(f_name, _name_ns, _id, _scope, f_args, _f_body))) => {
       check_fn_args(&f_args, &args, file_ns, &f_name, &def_name, check_warnings);
-      let mut ys = TernaryTreeList::from(&vec![head_form]);
+      let mut ys = TernaryTreeList::from(&[head_form]);
       for a in &args {
         let (form, _v) = preprocess_expr(a, scope_defs, file_ns, check_warnings, call_stack)?;
         ys = ys.push(form);
@@ -354,7 +354,7 @@ fn process_list_call(
       Ok((Calcit::List(ys), None))
     }
     (_, _) => {
-      let mut ys = TernaryTreeList::from(&vec![head_form]);
+      let mut ys = TernaryTreeList::from(&[head_form]);
       for a in &args {
         let (form, _v) = preprocess_expr(a, scope_defs, file_ns, check_warnings, call_stack)?;
         ys = ys.push(form);
@@ -454,7 +454,7 @@ pub fn preprocess_each_items(
   check_warnings: &RefCell<Vec<String>>,
   call_stack: &CallStackVec,
 ) -> Result<Calcit, CalcitErr> {
-  let mut xs: CalcitItems = TernaryTreeList::from(&vec![Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
+  let mut xs: CalcitItems = TernaryTreeList::from(&[Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
   for a in args {
     let (form, _v) = preprocess_expr(a, scope_defs, file_ns, check_warnings, call_stack)?;
     xs = xs.push(form);
@@ -472,7 +472,7 @@ pub fn preprocess_defn(
   call_stack: &CallStackVec,
 ) -> Result<Calcit, CalcitErr> {
   // println!("defn args: {}", primes::CrListWrap(args.to_owned()));
-  let mut xs: CalcitItems = TernaryTreeList::from(&vec![Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
+  let mut xs: CalcitItems = TernaryTreeList::from(&[Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
   match (args.get(0), args.get(1)) {
     (Some(Calcit::Symbol(def_name, def_name_ns, at_def, _)), Some(Calcit::List(ys))) => {
       let mut body_defs: HashSet<Box<str>> = scope_defs.to_owned();
@@ -550,7 +550,7 @@ pub fn preprocess_call_let(
   check_warnings: &RefCell<Vec<String>>,
   call_stack: &CallStackVec,
 ) -> Result<Calcit, CalcitErr> {
-  let mut xs: CalcitItems = TernaryTreeList::from(&vec![Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
+  let mut xs: CalcitItems = TernaryTreeList::from(&[Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
   let mut body_defs: HashSet<Box<str>> = scope_defs.to_owned();
   let binding = match args.get(0) {
     Some(Calcit::Nil) => Calcit::Nil,
@@ -559,7 +559,7 @@ pub fn preprocess_call_let(
         check_symbol(sym, args, check_warnings);
         body_defs.insert(sym.to_owned());
         let (form, _v) = preprocess_expr(a, &body_defs, file_ns, check_warnings, call_stack)?;
-        Calcit::List(TernaryTreeList::from(&vec![ys[0].to_owned(), form]))
+        Calcit::List(TernaryTreeList::from(&[ys[0].to_owned(), form]))
       }
       (a, b) => {
         return Err(CalcitErr::use_msg_stack(
@@ -604,7 +604,7 @@ pub fn preprocess_quote(
   _scope_defs: &HashSet<Box<str>>,
   _file_ns: &str,
 ) -> Result<Calcit, CalcitErr> {
-  let mut xs: CalcitItems = TernaryTreeList::from(&vec![Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
+  let mut xs: CalcitItems = TernaryTreeList::from(&[Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
   for a in args {
     xs = xs.push(a.to_owned());
   }
@@ -620,7 +620,7 @@ pub fn preprocess_defatom(
   check_warnings: &RefCell<Vec<String>>,
   call_stack: &CallStackVec,
 ) -> Result<Calcit, CalcitErr> {
-  let mut xs: CalcitItems = TernaryTreeList::from(&vec![Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
+  let mut xs: CalcitItems = TernaryTreeList::from(&[Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
   for a in args {
     // TODO
     let (form, _v) = preprocess_expr(a, scope_defs, file_ns, check_warnings, call_stack)?;
@@ -639,7 +639,7 @@ pub fn preprocess_quasiquote(
   check_warnings: &RefCell<Vec<String>>,
   call_stack: &CallStackVec,
 ) -> Result<Calcit, CalcitErr> {
-  let mut xs: CalcitItems = TernaryTreeList::from(&vec![Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
+  let mut xs: CalcitItems = TernaryTreeList::from(&[Calcit::Syntax(head.to_owned(), head_ns.to_owned().into())]);
   for a in args {
     xs = xs.push(preprocess_quasiquote_internal(a, scope_defs, file_ns, check_warnings, call_stack)?);
   }