diff --git a/Cargo.lock b/Cargo.lock
index a4969a2..7589a66 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -212,6 +212,16 @@ dependencies = [
  "crypto-common",
 ]
 
+[[package]]
+name = "duplicate"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "de78e66ac9061e030587b2a2e75cc88f22304913c907b11307bca737141230cb"
+dependencies = [
+ "heck",
+ "proc-macro-error",
+]
+
 [[package]]
 name = "dyn-clone"
 version = "1.0.11"
@@ -395,6 +405,7 @@ version = "0.2.2"
 dependencies = [
  "chumsky",
  "clap",
+ "duplicate",
  "dyn-clone",
  "hashbrown 0.13.2",
  "itertools",
@@ -420,6 +431,30 @@ version = "1.0.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9f746c4065a8fa3fe23974dd82f15431cc8d40779821001404d10d2e79ca7d79"
 
+[[package]]
+name = "proc-macro-error"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da25490ff9892aab3fcf7c36f08cfb902dd3e71ca0f9f9517bea02a73a5ce38c"
+dependencies = [
+ "proc-macro-error-attr",
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+ "version_check",
+]
+
+[[package]]
+name = "proc-macro-error-attr"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1be40180e52ecc98ad80b184934baf3d0d29f979574e439af5a55274b35f869"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "version_check",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.56"
diff --git a/Cargo.toml b/Cargo.toml
index 7e05313..9498940 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -32,3 +32,4 @@ clap = { version = "4.3", features = ["derive"] }
 trait-set = "0.3"
 paste = "1.0"
 rust-embed = { version = "6.6", features = ["include-exclude"] }
+duplicate = "1.0.0"
diff --git a/src/bin/main.rs b/src/bin/main.rs
index 68a94f9..05be6bf 100644
--- a/src/bin/main.rs
+++ b/src/bin/main.rs
@@ -2,13 +2,15 @@ mod cli;
 
 use std::fs::File;
 use std::path::{Path, PathBuf};
-use std::process;
+use std::{iter, process};
 
 use clap::Parser;
 use hashbrown::HashMap;
 use itertools::Itertools;
-use orchidlang::interner::{InternedDisplay, Interner, Sym};
-use orchidlang::{ast, ast_to_interpreted, interpreter, pipeline, rule, stl};
+use orchidlang::interner::{InternedDisplay, Interner};
+use orchidlang::{
+  ast, ast_to_interpreted, interpreter, pipeline, rule, stl, Stok, Sym, VName,
+};
 
 use crate::cli::cmd_prompt;
 
@@ -66,12 +68,16 @@ impl Args {
 /// Load and parse all source related to the symbol `target` or all symbols
 /// in the namespace `target` in the context of the STL. All sourcefiles must
 /// reside within `dir`.
-fn load_dir(dir: &Path, target: Sym, i: &Interner) -> pipeline::ProjectTree {
+fn load_dir(
+  dir: &Path,
+  target: &[Stok],
+  i: &Interner,
+) -> pipeline::ProjectTree<VName> {
   let file_cache = pipeline::file_loader::mk_dir_cache(dir.to_path_buf(), i);
   let library = stl::mk_stl(i, stl::StlOptions::default());
   pipeline::parse_layer(
-    &[target],
-    &|path| file_cache.find(&path),
+    iter::once(target),
+    &|path| file_cache.find(path),
     &library,
     &stl::mk_prelude(i),
     i,
@@ -79,12 +85,12 @@ fn load_dir(dir: &Path, target: Sym, i: &Interner) -> pipeline::ProjectTree {
   .expect("Failed to load source code")
 }
 
-pub fn to_sym(data: &str, i: &Interner) -> Sym {
-  i.i(&data.split("::").map(|s| i.i(s)).collect::<Vec<_>>()[..])
+pub fn to_vname(data: &str, i: &Interner) -> VName {
+  data.split("::").map(|s| i.i(s)).collect::<Vec<_>>()
 }
 
 /// A little utility to step through the resolution of a macro set
-pub fn macro_debug(repo: rule::Repo, mut code: ast::Expr, i: &Interner) {
+pub fn macro_debug(repo: rule::Repo, mut code: ast::Expr<Sym>, i: &Interner) {
   let mut idx = 0;
   println!("Macro debugger working on {}", code.bundle(i));
   loop {
@@ -119,8 +125,8 @@ pub fn main() {
   args.chk_proj().unwrap_or_else(|e| panic!("{e}"));
   let dir = PathBuf::try_from(args.dir).unwrap();
   let i = Interner::new();
-  let main = to_sym(&args.main, &i);
-  let project = load_dir(&dir, main, &i);
+  let main = to_vname(&args.main, &i);
+  let project = pipeline::vname_to_sym_tree(load_dir(&dir, &main, &i), &i);
   let rules = pipeline::collect_rules(&project);
   let consts = pipeline::collect_consts(&project, &i);
   let repo = rule::Repo::new(rules, &i).unwrap_or_else(|(rule, error)| {
@@ -135,7 +141,7 @@ pub fn main() {
     println!("Parsed rules: {}", repo.bundle(&i));
     return;
   } else if !args.macro_debug.is_empty() {
-    let name = to_sym(&args.macro_debug, &i);
+    let name = i.i(&to_vname(&args.macro_debug, &i));
     let code = consts
       .get(&name)
       .unwrap_or_else(|| panic!("Constant {} not found", args.macro_debug));
@@ -153,7 +159,7 @@ pub fn main() {
   }
   let ctx =
     interpreter::Context { symbols: &exec_table, interner: &i, gas: None };
-  let entrypoint = exec_table.get(&main).unwrap_or_else(|| {
+  let entrypoint = exec_table.get(&i.i(&main)).unwrap_or_else(|| {
     let main = args.main;
     let symbols =
       exec_table.keys().map(|t| i.extern_vec(*t).join("::")).join(", ");
diff --git a/src/interner/mod.rs b/src/interner/mod.rs
index a81a612..5b86a87 100644
--- a/src/interner/mod.rs
+++ b/src/interner/mod.rs
@@ -2,24 +2,12 @@
 //!
 //! Can be used to deduplicate various structures for fast equality comparisons.
 //! The parser uses it to intern strings.
-mod display;
 mod monotype;
 mod multitype;
 mod token;
+mod traits;
 
-pub use display::{DisplayBundle, InternedDisplay};
 pub use monotype::TypedInterner;
 pub use multitype::Interner;
 pub use token::Tok;
-
-/// A symbol, nsname, nname or namespaced name is a sequence of namespaces
-/// and an identifier. The [Vec] can never be empty.
-///
-/// Throughout different stages of processing, these names can be
-///
-/// - local names to be prefixed with the current module
-/// - imported names starting with a segment
-///   - ending a single import or
-///   - defined in one of the glob imported modules
-/// - absolute names
-pub type Sym = Tok<Vec<Tok<String>>>;
+pub use traits::{DisplayBundle, InternedDisplay, InternedInto};
diff --git a/src/interner/display.rs b/src/interner/traits.rs
similarity index 79%
rename from src/interner/display.rs
rename to src/interner/traits.rs
index fbecef0..e365802 100644
--- a/src/interner/display.rs
+++ b/src/interner/traits.rs
@@ -54,3 +54,18 @@ impl<'a, T: InternedDisplay + ?Sized> Display for DisplayBundle<'a, T> {
     self.data.fmt_i(f, self.interner)
   }
 }
+
+/// Conversions that are possible in the presence of an interner
+///
+/// Essentially, this allows to define abstractions over interned and
+/// non-interned versions of a type and convert between them
+pub trait InternedInto<U> {
+  /// Execute the conversion
+  fn into_i(self, i: &Interner) -> U;
+}
+
+impl<T: Into<U>, U> InternedInto<U> for T {
+  fn into_i(self, _i: &Interner) -> U {
+    self.into()
+  }
+}
diff --git a/src/interpreter/context.rs b/src/interpreter/context.rs
index 8439182..b5f95d7 100644
--- a/src/interpreter/context.rs
+++ b/src/interpreter/context.rs
@@ -1,7 +1,8 @@
 use hashbrown::HashMap;
 
-use crate::interner::{Interner, Sym};
+use crate::interner::Interner;
 use crate::representations::interpreted::ExprInst;
+use crate::Sym;
 
 /// All the data associated with an interpreter run
 #[derive(Clone)]
diff --git a/src/lib.rs b/src/lib.rs
index 4dd8e12..9aaa55b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -18,7 +18,10 @@ pub mod rule;
 pub mod stl;
 mod utils;
 
-pub use interner::Sym;
+use interner::Tok;
+pub use representations::{NameLike, Sym, VName};
+/// Element of VName and a common occurrence in the API
+pub type Stok = Tok<String>;
 pub use representations::ast_to_interpreted::ast_to_interpreted;
 pub use representations::{
   ast, interpreted, sourcefile, tree, Literal, Location, PathSet, Primitive,
diff --git a/src/parse/expression.rs b/src/parse/expression.rs
index 4020f2f..0a9507d 100644
--- a/src/parse/expression.rs
+++ b/src/parse/expression.rs
@@ -8,15 +8,14 @@ use super::context::Context;
 use super::decls::SimpleParser;
 use super::enum_filter::enum_filter;
 use super::lexer::{filter_map_lex, Entry, Lexeme};
-use crate::interner::Sym;
 use crate::representations::ast::{Clause, Expr};
 use crate::representations::location::Location;
-use crate::representations::Primitive;
+use crate::representations::{Primitive, VName};
 
 /// Parses any number of expr wrapped in (), [] or {}
 fn sexpr_parser(
-  expr: impl SimpleParser<Entry, Expr> + Clone,
-) -> impl SimpleParser<Entry, (Clause, Range<usize>)> + Clone {
+  expr: impl SimpleParser<Entry, Expr<VName>> + Clone,
+) -> impl SimpleParser<Entry, (Clause<VName>, Range<usize>)> + Clone {
   let body = expr.repeated();
   choice((
     Lexeme::LP('(').parser().then(body.clone()).then(Lexeme::RP('(').parser()),
@@ -40,9 +39,9 @@ fn sexpr_parser(
 /// and type and body are both expressions. Comments are allowed
 /// and ignored everywhere in between the tokens
 fn lambda_parser<'a>(
-  expr: impl SimpleParser<Entry, Expr> + Clone + 'a,
+  expr: impl SimpleParser<Entry, Expr<VName>> + Clone + 'a,
   ctx: impl Context + 'a,
-) -> impl SimpleParser<Entry, (Clause, Range<usize>)> + Clone + 'a {
+) -> impl SimpleParser<Entry, (Clause<VName>, Range<usize>)> + Clone + 'a {
   Lexeme::BS
     .parser()
     .ignore_then(expr.clone())
@@ -56,9 +55,8 @@ fn lambda_parser<'a>(
 
 /// Parses a sequence of names separated by :: <br/>
 /// Comments and line breaks are allowed and ignored in between
-pub fn ns_name_parser<'a>(
-  ctx: impl Context + 'a,
-) -> impl SimpleParser<Entry, (Sym, Range<usize>)> + Clone + 'a {
+pub fn ns_name_parser<'a>()
+-> impl SimpleParser<Entry, (VName, Range<usize>)> + Clone + 'a {
   filter_map_lex(enum_filter!(Lexeme::Name))
     .separated_by(Lexeme::NS.parser())
     .at_least(1)
@@ -66,32 +64,31 @@ pub fn ns_name_parser<'a>(
       let start = elements.first().expect("can never be empty").1.start;
       let end = elements.last().expect("can never be empty").1.end;
       let tokens = (elements.iter().map(|(t, _)| *t)).collect::<Vec<_>>();
-      (ctx.interner().i(&tokens), start..end)
+      (tokens, start..end)
     })
     .labelled("Namespaced name")
 }
 
-pub fn namelike_parser<'a>(
-  ctx: impl Context + 'a,
-) -> impl SimpleParser<Entry, (Clause, Range<usize>)> + Clone + 'a {
+pub fn namelike_parser<'a>()
+-> impl SimpleParser<Entry, (Clause<VName>, Range<usize>)> + Clone + 'a {
   choice((
     filter_map_lex(enum_filter!(Lexeme::PH))
       .map(|(ph, range)| (Clause::Placeh(ph), range)),
-    ns_name_parser(ctx).map(|(token, range)| (Clause::Name(token), range)),
+    ns_name_parser().map(|(token, range)| (Clause::Name(token), range)),
   ))
 }
 
 pub fn clause_parser<'a>(
-  expr: impl SimpleParser<Entry, Expr> + Clone + 'a,
+  expr: impl SimpleParser<Entry, Expr<VName>> + Clone + 'a,
   ctx: impl Context + 'a,
-) -> impl SimpleParser<Entry, (Clause, Range<usize>)> + Clone + 'a {
+) -> impl SimpleParser<Entry, (Clause<VName>, Range<usize>)> + Clone + 'a {
   choice((
     filter_map_lex(enum_filter!(Lexeme >> Primitive; Literal))
       .map(|(p, s)| (Clause::P(p), s))
       .labelled("Literal"),
     sexpr_parser(expr.clone()),
-    lambda_parser(expr, ctx.clone()),
-    namelike_parser(ctx),
+    lambda_parser(expr, ctx),
+    namelike_parser(),
   ))
   .labelled("Clause")
 }
@@ -99,7 +96,7 @@ pub fn clause_parser<'a>(
 /// Parse an expression
 pub fn xpr_parser<'a>(
   ctx: impl Context + 'a,
-) -> impl SimpleParser<Entry, Expr> + 'a {
+) -> impl SimpleParser<Entry, Expr<VName>> + 'a {
   recursive(move |expr| {
     clause_parser(expr, ctx.clone()).map(move |(value, range)| Expr {
       value,
diff --git a/src/parse/sourcefile.rs b/src/parse/sourcefile.rs
index 4384d6c..1271e03 100644
--- a/src/parse/sourcefile.rs
+++ b/src/parse/sourcefile.rs
@@ -15,20 +15,17 @@ use super::Entry;
 use crate::ast::{Clause, Constant, Expr, Rule};
 use crate::representations::location::Location;
 use crate::representations::sourcefile::{FileEntry, Member, Namespace};
+use crate::representations::VName;
 
 fn rule_parser<'a>(
   ctx: impl Context + 'a,
-) -> impl SimpleParser<Entry, Rule> + 'a {
+) -> impl SimpleParser<Entry, Rule<VName>> + 'a {
   xpr_parser(ctx.clone())
     .repeated()
     .at_least(1)
     .then(filter_map_lex(enum_filter!(Lexeme::Rule)))
     .then(xpr_parser(ctx).repeated().at_least(1))
-    .map(|((p, (prio, _)), t)| Rule {
-      pattern: Rc::new(p),
-      prio,
-      template: Rc::new(t),
-    })
+    .map(|((p, (prio, _)), t)| Rule { pattern: p, prio, template: t })
     .labelled("Rule")
 }
 
diff --git a/src/pipeline/file_loader.rs b/src/pipeline/file_loader.rs
index a964be2..676d6de 100644
--- a/src/pipeline/file_loader.rs
+++ b/src/pipeline/file_loader.rs
@@ -6,12 +6,11 @@ use std::{fs, io};
 use chumsky::text::Character;
 use rust_embed::RustEmbed;
 
-use crate::interner::{Interner, Sym};
-use crate::pipeline::error::{
-  ErrorPosition, ProjectError, UnexpectedDirectory,
-};
+use crate::interner::Interner;
+use crate::pipeline::error::{ErrorPosition, ProjectError};
 use crate::utils::iter::box_once;
 use crate::utils::{BoxedIter, Cache};
+use crate::{Stok, VName};
 
 /// All the data available about a failed source load call
 #[derive(Debug)]
@@ -89,9 +88,9 @@ pub fn load_file(root: &Path, path: &[impl AsRef<str>]) -> IOResult {
 }
 
 /// Generates a cached file loader for a directory
-pub fn mk_dir_cache(root: PathBuf, i: &Interner) -> Cache<Sym, IOResult> {
-  Cache::new(move |token: Sym, _this| -> IOResult {
-    let path = i.r(token).iter().map(|t| i.r(*t).as_str()).collect::<Vec<_>>();
+pub fn mk_dir_cache(root: PathBuf, i: &Interner) -> Cache<VName, IOResult> {
+  Cache::new(move |vname: VName, _this| -> IOResult {
+    let path = vname.iter().map(|t| i.r(*t).as_str()).collect::<Vec<_>>();
     load_file(&root, &path)
   })
 }
@@ -128,28 +127,9 @@ pub fn load_embed<T: 'static + RustEmbed>(path: &str, ext: &str) -> IOResult {
 pub fn mk_embed_cache<'a, T: 'static + RustEmbed>(
   ext: &'a str,
   i: &'a Interner,
-) -> Cache<'a, Sym, IOResult> {
-  Cache::new(move |token: Sym, _this| -> IOResult {
-    let path = i.extern_vec(token).join("/");
+) -> Cache<'a, Vec<Stok>, IOResult> {
+  Cache::new(move |vname: VName, _this| -> IOResult {
+    let path = i.extern_all(&vname).join("/");
     load_embed::<T>(&path, ext)
   })
 }
-
-/// Loads the string contents of a file at the given location.
-/// If the path points to a directory, raises an error.
-pub fn load_text(
-  path: Sym,
-  load_file: &impl Fn(Sym) -> IOResult,
-  i: &Interner,
-) -> Result<Rc<String>, Rc<dyn ProjectError>> {
-  if let Loaded::Code(s) = load_file(path)? {
-    Ok(s)
-  } else {
-    Err(
-      UnexpectedDirectory {
-        path: i.r(path).iter().map(|t| i.r(*t)).cloned().collect(),
-      }
-      .rc(),
-    )
-  }
-}
diff --git a/src/pipeline/import_resolution/alias_map.rs b/src/pipeline/import_resolution/alias_map.rs
index 63ab3fc..751a999 100644
--- a/src/pipeline/import_resolution/alias_map.rs
+++ b/src/pipeline/import_resolution/alias_map.rs
@@ -2,22 +2,22 @@ use std::hash::Hash;
 
 use hashbrown::{HashMap, HashSet};
 
-use crate::interner::Sym;
+use crate::interner::Tok;
 
 #[derive(Clone, Debug, Default)]
 pub struct AliasMap {
-  pub targets: HashMap<Sym, Sym>,
-  pub aliases: HashMap<Sym, HashSet<Sym>>,
+  pub targets: HashMap<Vec<Tok<String>>, Vec<Tok<String>>>,
+  pub aliases: HashMap<Vec<Tok<String>>, HashSet<Vec<Tok<String>>>>,
 }
 impl AliasMap {
   pub fn new() -> Self {
     Self::default()
   }
 
-  pub fn link(&mut self, alias: Sym, target: Sym) {
-    let prev = self.targets.insert(alias, target);
+  pub fn link(&mut self, alias: Vec<Tok<String>>, target: Vec<Tok<String>>) {
+    let prev = self.targets.insert(alias.clone(), target.clone());
     debug_assert!(prev.is_none(), "Alias already has a target");
-    multimap_entry(&mut self.aliases, &target).insert(alias);
+    multimap_entry(&mut self.aliases, &target).insert(alias.clone());
     // Remove aliases of the alias
     if let Some(alts) = self.aliases.remove(&alias) {
       for alt in alts {
@@ -26,17 +26,18 @@ impl AliasMap {
           self.aliases.get(&alt).map(HashSet::is_empty).unwrap_or(true),
           "Alias set of alias not empty"
         );
+        let alt_target = self.targets.insert(alt.clone(), target.clone());
         debug_assert!(
-          self.targets.insert(alt, target) == Some(alias),
+          alt_target.as_ref() == Some(&alias),
           "Name not target of its own alias"
         );
-        multimap_entry(&mut self.aliases, &target).insert(alt);
+        multimap_entry(&mut self.aliases, &alias).insert(alt);
       }
     }
   }
 
-  pub fn resolve(&self, alias: Sym) -> Option<Sym> {
-    self.targets.get(&alias).copied()
+  pub fn resolve(&self, alias: &[Tok<String>]) -> Option<&Vec<Tok<String>>> {
+    self.targets.get(alias)
   }
 }
 
diff --git a/src/pipeline/import_resolution/apply_aliases.rs b/src/pipeline/import_resolution/apply_aliases.rs
index 15e5e78..cf24b30 100644
--- a/src/pipeline/import_resolution/apply_aliases.rs
+++ b/src/pipeline/import_resolution/apply_aliases.rs
@@ -1,24 +1,22 @@
-use std::rc::Rc;
-
 use hashbrown::HashMap;
 
 use super::alias_map::AliasMap;
 use super::decls::{InjectedAsFn, UpdatedFn};
 use crate::ast::{Expr, Rule};
-use crate::interner::{Interner, Sym, Tok};
+use crate::interner::Tok;
 use crate::pipeline::{ProjectExt, ProjectModule};
 use crate::representations::tree::{ModEntry, ModMember};
+use crate::representations::VName;
 use crate::utils::Substack;
 
 fn resolve_rec(
-  token: Sym,
+  namespace: &[Tok<String>],
   alias_map: &AliasMap,
-  i: &Interner,
 ) -> Option<Vec<Tok<String>>> {
-  if let Some(alias) = alias_map.resolve(token) {
-    Some(i.r(alias).clone())
-  } else if let Some((foot, body)) = i.r(token).split_last() {
-    let mut new_beginning = resolve_rec(i.i(body), alias_map, i)?;
+  if let Some(alias) = alias_map.resolve(namespace) {
+    Some(alias.clone())
+  } else if let Some((foot, body)) = namespace.split_last() {
+    let mut new_beginning = resolve_rec(body, alias_map)?;
     new_beginning.push(*foot);
     Some(new_beginning)
   } else {
@@ -27,25 +25,23 @@ fn resolve_rec(
 }
 
 fn resolve(
-  token: Sym,
+  namespace: &[Tok<String>],
   alias_map: &AliasMap,
   injected_as: &impl InjectedAsFn,
-  i: &Interner,
-) -> Option<Sym> {
-  injected_as(&i.r(token)[..]).or_else(|| {
-    let next_v = resolve_rec(token, alias_map, i)?;
-    Some(injected_as(&next_v).unwrap_or_else(|| i.i(&next_v)))
+) -> Option<Vec<Tok<String>>> {
+  injected_as(namespace).or_else(|| {
+    let next_v = resolve_rec(namespace, alias_map)?;
+    Some(injected_as(&next_v).unwrap_or(next_v))
   })
 }
 
 fn process_expr(
-  expr: &Expr,
+  expr: &Expr<VName>,
   alias_map: &AliasMap,
   injected_as: &impl InjectedAsFn,
-  i: &Interner,
-) -> Expr {
+) -> Expr<VName> {
   expr
-    .map_names(&|n| resolve(n, alias_map, injected_as, i))
+    .map_names(&|n| resolve(n, alias_map, injected_as))
     .unwrap_or_else(|| expr.clone())
 }
 
@@ -53,32 +49,23 @@ fn process_expr(
 /// Replace all aliases with the name they're originally defined as
 fn apply_aliases_rec(
   path: Substack<Tok<String>>,
-  module: &ProjectModule,
+  module: &ProjectModule<VName>,
   alias_map: &AliasMap,
-  i: &Interner,
   injected_as: &impl InjectedAsFn,
   updated: &impl UpdatedFn,
-) -> ProjectModule {
+) -> ProjectModule<VName> {
   let items = (module.items.iter())
     .map(|(name, ent)| {
       let ModEntry { exported, member } = ent;
       let member = match member {
         ModMember::Item(expr) =>
-          ModMember::Item(process_expr(expr, alias_map, injected_as, i)),
+          ModMember::Item(process_expr(expr, alias_map, injected_as)),
         ModMember::Sub(module) => {
           let subpath = path.push(*name);
           let new_mod = if !updated(&subpath.iter().rev_vec_clone()) {
             module.clone()
           } else {
-            let module = module.as_ref();
-            Rc::new(apply_aliases_rec(
-              subpath,
-              module,
-              alias_map,
-              i,
-              injected_as,
-              updated,
-            ))
+            apply_aliases_rec(subpath, module, alias_map, injected_as, updated)
           };
           ModMember::Sub(new_mod)
         },
@@ -91,16 +78,12 @@ fn apply_aliases_rec(
       let Rule { pattern, prio, template } = rule;
       Rule {
         prio: *prio,
-        pattern: Rc::new(
-          (pattern.iter())
-            .map(|expr| process_expr(expr, alias_map, injected_as, i))
-            .collect::<Vec<_>>(),
-        ),
-        template: Rc::new(
-          (template.iter())
-            .map(|expr| process_expr(expr, alias_map, injected_as, i))
-            .collect::<Vec<_>>(),
-        ),
+        pattern: (pattern.iter())
+          .map(|expr| process_expr(expr, alias_map, injected_as))
+          .collect::<Vec<_>>(),
+        template: (template.iter())
+          .map(|expr| process_expr(expr, alias_map, injected_as))
+          .collect::<Vec<_>>(),
       }
     })
     .collect::<Vec<_>>();
@@ -111,7 +94,7 @@ fn apply_aliases_rec(
       rules,
       exports: (module.extra.exports.iter())
         .map(|(k, v)| {
-          (*k, resolve(*v, alias_map, injected_as, i).unwrap_or(*v))
+          (*k, resolve(v, alias_map, injected_as).unwrap_or(v.clone()))
         })
         .collect(),
       file: module.extra.file.clone(),
@@ -121,18 +104,10 @@ fn apply_aliases_rec(
 }
 
 pub fn apply_aliases(
-  module: &ProjectModule,
+  module: &ProjectModule<VName>,
   alias_map: &AliasMap,
-  i: &Interner,
   injected_as: &impl InjectedAsFn,
   updated: &impl UpdatedFn,
-) -> ProjectModule {
-  apply_aliases_rec(
-    Substack::Bottom,
-    module,
-    alias_map,
-    i,
-    injected_as,
-    updated,
-  )
+) -> ProjectModule<VName> {
+  apply_aliases_rec(Substack::Bottom, module, alias_map, injected_as, updated)
 }
diff --git a/src/pipeline/import_resolution/collect_aliases.rs b/src/pipeline/import_resolution/collect_aliases.rs
index d9e554c..45930a2 100644
--- a/src/pipeline/import_resolution/collect_aliases.rs
+++ b/src/pipeline/import_resolution/collect_aliases.rs
@@ -7,21 +7,23 @@ use crate::interner::{Interner, Tok};
 use crate::pipeline::error::{NotExported, ProjectError};
 use crate::pipeline::project_tree::{split_path, ProjectModule, ProjectTree};
 use crate::representations::tree::{ModMember, WalkErrorKind};
+use crate::representations::VName;
 use crate::utils::{pushed, unwrap_or, Substack};
 
 /// Assert that a module identified by a path can see a given symbol
 fn assert_visible(
   source: &[Tok<String>], // must point to a file or submodule
   target: &[Tok<String>], // may point to a symbol or module of any kind
-  project: &ProjectTree,
+  project: &ProjectTree<VName>,
   i: &Interner,
 ) -> Result<(), Rc<dyn ProjectError>> {
   let (tgt_item, tgt_path) = unwrap_or!(target.split_last(); return Ok(()));
   let shared_len =
     source.iter().zip(tgt_path.iter()).take_while(|(a, b)| a == b).count();
   let vis_ignored_len = usize::min(tgt_path.len(), shared_len + 1);
-  let private_root =
-    (project.0).walk(&tgt_path[..vis_ignored_len], false).unwrap_or_else(|e| {
+  let private_root = (project.0)
+    .walk_ref(&tgt_path[..vis_ignored_len], false)
+    .unwrap_or_else(|e| {
       let path_slc = &tgt_path[..vis_ignored_len];
       let bad_path = i.extern_all(path_slc).join("::");
       eprintln!(
@@ -32,7 +34,7 @@ fn assert_visible(
       panic!("")
     });
   let direct_parent = private_root
-    .walk(&tgt_path[vis_ignored_len..], true)
+    .walk_ref(&tgt_path[vis_ignored_len..], true)
     .map_err(|e| match e.kind {
       WalkErrorKind::Missing => panic!("checked in parsing"),
       WalkErrorKind::Private => {
@@ -70,8 +72,8 @@ fn assert_visible(
 /// Populate target and alias maps from the module tree recursively
 fn collect_aliases_rec(
   path: Substack<Tok<String>>,
-  module: &ProjectModule,
-  project: &ProjectTree,
+  module: &ProjectModule<VName>,
+  project: &ProjectTree<VName>,
   alias_map: &mut AliasMap,
   i: &Interner,
   updated: &impl UpdatedFn,
@@ -81,31 +83,29 @@ fn collect_aliases_rec(
   if !updated(&mod_path_v) {
     return Ok(());
   };
-  for (&name, &target_mod_name) in module.extra.imports_from.iter() {
-    let target_mod_v = i.r(target_mod_name);
-    let target_sym_v = pushed(target_mod_v, name);
+  for (&name, target_mod_name) in module.extra.imports_from.iter() {
+    let target_sym_v = pushed(target_mod_name, name);
     assert_visible(&mod_path_v, &target_sym_v, project, i)?;
     let sym_path_v = pushed(&mod_path_v, name);
-    let sym_path = i.i(&sym_path_v);
-    let target_mod = (project.0.walk(target_mod_v, false))
+    let target_mod = (project.0.walk_ref(target_mod_name, false))
       .expect("checked above in assert_visible");
-    let target_sym =
-      *target_mod.extra.exports.get(&name).unwrap_or_else(|| {
+    let target_sym = target_mod
+      .extra
+      .exports
+      .get(&name)
+      .unwrap_or_else(|| {
         panic!(
           "error in {}, {} has no member {}",
           i.extern_all(&mod_path_v).join("::"),
-          i.extern_all(target_mod_v).join("::"),
+          i.extern_all(target_mod_name).join("::"),
           i.r(name)
         )
-      });
-    alias_map.link(sym_path, target_sym);
+      })
+      .clone();
+    alias_map.link(sym_path_v, target_sym);
   }
   for (&name, entry) in module.items.iter() {
-    let submodule = if let ModMember::Sub(s) = &entry.member {
-      s.as_ref()
-    } else {
-      continue;
-    };
+    let submodule = unwrap_or!(&entry.member => ModMember::Sub; continue);
     collect_aliases_rec(
       path.push(name),
       submodule,
@@ -120,8 +120,8 @@ fn collect_aliases_rec(
 
 /// Populate target and alias maps from the module tree
 pub fn collect_aliases(
-  module: &ProjectModule,
-  project: &ProjectTree,
+  module: &ProjectModule<VName>,
+  project: &ProjectTree<VName>,
   alias_map: &mut AliasMap,
   i: &Interner,
   updated: &impl UpdatedFn,
diff --git a/src/pipeline/import_resolution/decls.rs b/src/pipeline/import_resolution/decls.rs
index bd735b1..f464131 100644
--- a/src/pipeline/import_resolution/decls.rs
+++ b/src/pipeline/import_resolution/decls.rs
@@ -1,8 +1,8 @@
 use trait_set::trait_set;
 
-use crate::interner::{Sym, Tok};
+use crate::interner::Tok;
 
 trait_set! {
-  pub trait InjectedAsFn = Fn(&[Tok<String>]) -> Option<Sym>;
+  pub trait InjectedAsFn = Fn(&[Tok<String>]) -> Option<Vec<Tok<String>>>;
   pub trait UpdatedFn = Fn(&[Tok<String>]) -> bool;
 }
diff --git a/src/pipeline/import_resolution/resolve_imports.rs b/src/pipeline/import_resolution/resolve_imports.rs
index c9bcd14..f33d259 100644
--- a/src/pipeline/import_resolution/resolve_imports.rs
+++ b/src/pipeline/import_resolution/resolve_imports.rs
@@ -7,18 +7,18 @@ use super::decls::{InjectedAsFn, UpdatedFn};
 use crate::interner::Interner;
 use crate::pipeline::error::ProjectError;
 use crate::pipeline::project_tree::ProjectTree;
+use crate::representations::VName;
 
 /// Follow import chains to locate the original name of all tokens, then
 /// replace these aliases with the original names throughout the tree
 pub fn resolve_imports(
-  project: ProjectTree,
+  project: ProjectTree<VName>,
   i: &Interner,
   injected_as: &impl InjectedAsFn,
   updated: &impl UpdatedFn,
-) -> Result<ProjectTree, Rc<dyn ProjectError>> {
+) -> Result<ProjectTree<VName>, Rc<dyn ProjectError>> {
   let mut map = AliasMap::new();
-  collect_aliases(project.0.as_ref(), &project, &mut map, i, updated)?;
-  let new_mod =
-    apply_aliases(project.0.as_ref(), &map, i, injected_as, updated);
-  Ok(ProjectTree(Rc::new(new_mod)))
+  collect_aliases(&project.0, &project, &mut map, i, updated)?;
+  let new_mod = apply_aliases(&project.0, &map, injected_as, updated);
+  Ok(ProjectTree(new_mod))
 }
diff --git a/src/pipeline/mod.rs b/src/pipeline/mod.rs
index 3b06847..0fa5532 100644
--- a/src/pipeline/mod.rs
+++ b/src/pipeline/mod.rs
@@ -9,6 +9,6 @@ mod source_loader;
 
 pub use parse_layer::parse_layer;
 pub use project_tree::{
-  collect_consts, collect_rules, from_const_tree, ConstTree, ProjectExt,
-  ProjectModule, ProjectTree,
+  collect_consts, collect_rules, from_const_tree, vname_to_sym_tree, ConstTree,
+  ProjectExt, ProjectModule, ProjectTree,
 };
diff --git a/src/pipeline/parse_layer.rs b/src/pipeline/parse_layer.rs
index 23efedb..ac1707f 100644
--- a/src/pipeline/parse_layer.rs
+++ b/src/pipeline/parse_layer.rs
@@ -3,8 +3,9 @@ use std::rc::Rc;
 use super::error::ProjectError;
 use super::file_loader::IOResult;
 use super::{import_resolution, project_tree, source_loader, ProjectTree};
-use crate::interner::{Interner, Sym, Tok};
+use crate::interner::{Interner, Tok};
 use crate::representations::sourcefile::FileEntry;
+use crate::representations::VName;
 
 /// Using an IO callback, produce a project tree that includes the given
 /// target symbols or files if they're defined.
@@ -14,35 +15,32 @@ use crate::representations::sourcefile::FileEntry;
 /// prelude which will be prepended to each individual file. Since the
 /// prelude gets compiled with each file, normally it should be a glob
 /// import pointing to a module in the environment.
-pub fn parse_layer(
-  targets: &[Sym],
-  loader: &impl Fn(Sym) -> IOResult,
-  environment: &ProjectTree,
+pub fn parse_layer<'a>(
+  targets: impl Iterator<Item = &'a [Tok<String>]>,
+  loader: &impl Fn(&[Tok<String>]) -> IOResult,
+  environment: &'a ProjectTree<VName>,
   prelude: &[FileEntry],
   i: &Interner,
-) -> Result<ProjectTree, Rc<dyn ProjectError>> {
+) -> Result<ProjectTree<VName>, Rc<dyn ProjectError>> {
   // A path is injected if it is walkable in the injected tree
   let injected_as = |path: &[Tok<String>]| {
     let (item, modpath) = path.split_last()?;
-    let module = environment.0.walk(modpath, false).ok()?;
-    let inj = module.extra.exports.get(item).copied()?;
-    Some(inj)
+    let module = environment.0.walk_ref(modpath, false).ok()?;
+    module.extra.exports.get(item).cloned()
   };
   let injected_names = |path: Tok<Vec<Tok<String>>>| {
-    let module = environment.0.walk(&i.r(path)[..], false).ok()?;
+    let module = environment.0.walk_ref(&i.r(path)[..], false).ok()?;
     Some(Rc::new(module.extra.exports.keys().copied().collect()))
   };
   let source =
     source_loader::load_source(targets, prelude, i, loader, &|path| {
-      environment.0.walk(&i.r(path)[..], false).is_ok()
+      environment.0.walk_ref(path, false).is_ok()
     })?;
   let tree = project_tree::build_tree(source, i, prelude, &injected_names)?;
-  let sum = ProjectTree(Rc::new(
-    environment.0.as_ref().clone().overlay(tree.0.as_ref().clone()),
-  ));
+  let sum = ProjectTree(environment.0.clone().overlay(tree.0.clone()));
   let resolvd =
     import_resolution::resolve_imports(sum, i, &injected_as, &|path| {
-      tree.0.walk(path, false).is_ok()
+      tree.0.walk_ref(path, false).is_ok()
     })?;
   // Addition among modules favours the left hand side.
   Ok(resolvd)
diff --git a/src/pipeline/project_tree/build_tree.rs b/src/pipeline/project_tree/build_tree.rs
index 62e722e..29af43a 100644
--- a/src/pipeline/project_tree/build_tree.rs
+++ b/src/pipeline/project_tree/build_tree.rs
@@ -12,8 +12,9 @@ use crate::pipeline::error::ProjectError;
 use crate::pipeline::source_loader::{LoadedSource, LoadedSourceTable};
 use crate::representations::sourcefile::{absolute_path, FileEntry, Member};
 use crate::representations::tree::{ModEntry, ModMember, Module};
+use crate::representations::{NameLike, VName};
 use crate::utils::iter::{box_empty, box_once};
-use crate::utils::{pushed, Substack};
+use crate::utils::{pushed, unwrap_or, Substack};
 
 #[derive(Debug)]
 struct ParsedSource<'a> {
@@ -24,7 +25,7 @@ struct ParsedSource<'a> {
 
 pub fn split_path<'a>(
   path: &'a [Tok<String>],
-  proj: &'a ProjectTree,
+  proj: &'a ProjectTree<impl NameLike>,
 ) -> (&'a [Tok<String>], &'a [Tok<String>]) {
   let (end, body) = if let Some(s) = path.split_last() {
     s
@@ -32,9 +33,9 @@ pub fn split_path<'a>(
     return (&[], &[]);
   };
   let mut module =
-    proj.0.walk(body, false).expect("invalid path cannot be split");
+    proj.0.walk_ref(body, false).expect("invalid path cannot be split");
   if let ModMember::Sub(m) = &module.items[end].member {
-    module = m.clone();
+    module = m;
   }
   let file =
     module.extra.file.as_ref().map(|s| &path[..s.len()]).unwrap_or(path);
@@ -52,7 +53,7 @@ fn source_to_module(
   // context
   i: &Interner,
   filepath_len: usize,
-) -> Rc<Module<Expr, ProjectExt>> {
+) -> Module<Expr<VName>, ProjectExt<VName>> {
   let path_v = path.iter().rev_vec_clone();
   let imports = data
     .iter()
@@ -70,13 +71,13 @@ fn source_to_module(
       let mut abs_path =
         absolute_path(&path_v, &imp_path_v, i).expect("tested in preparsing");
       let name = abs_path.pop().expect("importing the global context");
-      (name, i.i(&abs_path))
+      (name, abs_path)
     })
     .collect::<HashMap<_, _>>();
   let exports = data
     .iter()
     .flat_map(|ent| {
-      let mk_ent = |name| (name, i.i(&pushed(&path_v, name)));
+      let mk_ent = |name| (name, pushed(&path_v, name));
       match ent {
         FileEntry::Export(names) => Box::new(names.iter().copied().map(mk_ent)),
         FileEntry::Exported(mem) => match mem {
@@ -86,8 +87,8 @@ fn source_to_module(
             let mut names = Vec::new();
             for e in rule.pattern.iter() {
               e.visit_names(Substack::Bottom, &mut |n| {
-                if let Some([name]) = i.r(n).strip_prefix(&path_v[..]) {
-                  names.push((*name, n))
+                if let Some([name]) = n.strip_prefix(&path_v[..]) {
+                  names.push((*name, n.clone()))
                 }
               })
             }
@@ -109,58 +110,37 @@ fn source_to_module(
     .collect::<Vec<_>>();
   let items = data
     .into_iter()
-    .filter_map(|ent| match ent {
-      FileEntry::Exported(Member::Namespace(ns)) => {
-        let prep_member = &preparsed.items[&ns.name].member;
-        let new_prep = if let ModMember::Sub(s) = prep_member {
-          s.as_ref()
-        } else {
-          panic!("preparsed missing a submodule")
-        };
-        let module = source_to_module(
-          path.push(ns.name),
-          new_prep,
-          ns.body,
-          i,
-          filepath_len,
-        );
-        let member = ModMember::Sub(module);
-        Some((ns.name, ModEntry { exported: true, member }))
-      },
-      FileEntry::Internal(Member::Namespace(ns)) => {
-        let prep_member = &preparsed.items[&ns.name].member;
-        let new_prep = if let ModMember::Sub(s) = prep_member {
-          s.as_ref()
-        } else {
-          panic!("preparsed missing a submodule")
-        };
-        let module = source_to_module(
-          path.push(ns.name),
-          new_prep,
-          ns.body,
-          i,
-          filepath_len,
-        );
-        let member = ModMember::Sub(module);
-        Some((ns.name, ModEntry { exported: false, member }))
-      },
-      FileEntry::Exported(Member::Constant(Constant { name, value })) => {
-        let member = ModMember::Item(value);
-        Some((name, ModEntry { exported: true, member }))
-      },
-      FileEntry::Internal(Member::Constant(Constant { name, value })) => {
-        let member = ModMember::Item(value);
-        Some((name, ModEntry { exported: false, member }))
-      },
-      _ => None,
+    .filter_map(|ent| {
+      let member_to_item = |exported, member| match member {
+        Member::Namespace(ns) => {
+          let new_prep = unwrap_or!(
+            &preparsed.items[&ns.name].member => ModMember::Sub;
+            panic!("preparsed missing a submodule")
+          );
+          let module = source_to_module(
+            path.push(ns.name),
+            new_prep,
+            ns.body,
+            i,
+            filepath_len,
+          );
+          let member = ModMember::Sub(module);
+          Some((ns.name, ModEntry { exported, member }))
+        },
+        Member::Constant(Constant { name, value }) => {
+          let member = ModMember::Item(value);
+          Some((name, ModEntry { exported, member }))
+        },
+        _ => None,
+      };
+      match ent {
+        FileEntry::Exported(member) => member_to_item(true, member),
+        FileEntry::Internal(member) => member_to_item(false, member),
+        _ => None,
+      }
     })
     .collect::<HashMap<_, _>>();
-  // println!(
-  //   "Constructing file-module {} with members ({})",
-  //   i.extern_all(&path_v[..]).join("::"),
-  //   exports.keys().map(|t| i.r(*t)).join(", ")
-  // );
-  Rc::new(Module {
+  Module {
     imports,
     items,
     extra: ProjectExt {
@@ -169,14 +149,14 @@ fn source_to_module(
       rules,
       file: Some(path_v[..filepath_len].to_vec()),
     },
-  })
+  }
 }
 
 fn files_to_module(
   path: Substack<Tok<String>>,
   files: Vec<ParsedSource>,
   i: &Interner,
-) -> Rc<Module<Expr, ProjectExt>> {
+) -> Module<Expr<VName>, ProjectExt<VName>> {
   let lvl = path.len();
   debug_assert!(
     files.iter().map(|f| f.path.len()).max().unwrap() >= lvl,
@@ -186,7 +166,7 @@ fn files_to_module(
   if files.len() == 1 && files[0].path.len() == lvl {
     return source_to_module(
       path,
-      files[0].loaded.preparsed.0.as_ref(),
+      &files[0].loaded.preparsed.0,
       files[0].parsed.clone(),
       i,
       path.len(),
@@ -204,12 +184,9 @@ fn files_to_module(
       (namespace, ModEntry { exported: true, member })
     })
     .collect::<HashMap<_, _>>();
-  let exports: HashMap<_, _> = items
-    .keys()
-    .copied()
-    .map(|name| (name, i.i(&pushed(&path_v, name))))
-    .collect();
-  Rc::new(Module {
+  let exports: HashMap<_, _> =
+    items.keys().copied().map(|name| (name, pushed(&path_v, name))).collect();
+  Module {
     items,
     imports: vec![],
     extra: ProjectExt {
@@ -218,7 +195,7 @@ fn files_to_module(
       rules: vec![],
       file: None,
     },
-  })
+  }
 }
 
 pub fn build_tree(
@@ -226,17 +203,13 @@ pub fn build_tree(
   i: &Interner,
   prelude: &[FileEntry],
   injected: &impl InjectedOperatorsFn,
-) -> Result<ProjectTree, Rc<dyn ProjectError>> {
+) -> Result<ProjectTree<VName>, Rc<dyn ProjectError>> {
   assert!(!files.is_empty(), "A tree requires at least one module");
   let ops_cache = collect_ops::mk_cache(&files, i, injected);
   let mut entries = files
     .iter()
     .map(|(path, loaded)| {
-      Ok((
-        i.r(*path),
-        loaded,
-        parse_file(*path, &files, &ops_cache, i, prelude)?,
-      ))
+      Ok((path, loaded, parse_file(path, &files, &ops_cache, i, prelude)?))
     })
     .collect::<Result<Vec<_>, Rc<dyn ProjectError>>>()?;
   // sort by similarity, then longest-first
diff --git a/src/pipeline/project_tree/collect_ops/exported_ops.rs b/src/pipeline/project_tree/collect_ops/exported_ops.rs
index 827dcb7..35122f2 100644
--- a/src/pipeline/project_tree/collect_ops/exported_ops.rs
+++ b/src/pipeline/project_tree/collect_ops/exported_ops.rs
@@ -3,11 +3,12 @@ use std::rc::Rc;
 use hashbrown::HashSet;
 use trait_set::trait_set;
 
-use crate::interner::{Interner, Sym, Tok};
+use crate::interner::{Interner, Tok};
 use crate::pipeline::error::{ModuleNotFound, ProjectError};
 use crate::pipeline::source_loader::LoadedSourceTable;
 use crate::representations::tree::WalkErrorKind;
 use crate::utils::{split_max_prefix, unwrap_or, Cache};
+use crate::Sym;
 
 pub type OpsResult = Result<Rc<HashSet<Tok<String>>>, Rc<dyn ProjectError>>;
 pub type ExportedOpsCache<'a> = Cache<'a, Sym, OpsResult>;
@@ -31,16 +32,13 @@ pub fn collect_exported_ops(
   injected: &impl InjectedOperatorsFn,
 ) -> OpsResult {
   let injected = injected(path).unwrap_or_else(|| Rc::new(HashSet::new()));
-  let is_file = |n: &[Tok<String>]| loaded.contains_key(&i.i(n));
   let path_s = &i.r(path)[..];
-  let name_split = split_max_prefix(path_s, &is_file);
-  let (fpath_v, subpath_v) = unwrap_or!(name_split; return Ok(Rc::new(
+  let name_split = split_max_prefix(path_s, &|n| loaded.contains_key(n));
+  let (fpath, subpath) = unwrap_or!(name_split; return Ok(Rc::new(
     (loaded.keys())
-      .copied()
       .filter_map(|modname| {
-        let modname_s = i.r(modname);
-        if path_s.len() == coprefix(path_s.iter(), modname_s.iter()) {
-          Some(modname_s[path_s.len()])
+        if path_s.len() == coprefix(path_s.iter(), modname.iter()) {
+          Some(modname[path_s.len()])
         } else {
           None
         }
@@ -48,24 +46,24 @@ pub fn collect_exported_ops(
       .chain(injected.iter().copied())
       .collect::<HashSet<_>>(),
   )));
-  let fpath = i.i(fpath_v);
-  let preparsed = &loaded[&fpath].preparsed;
-  let module = preparsed.0.walk(subpath_v, false).map_err(|walk_err| {
-    match walk_err.kind {
-      WalkErrorKind::Private => {
-        unreachable!("visibility is not being checked here")
+  let preparsed = &loaded[fpath].preparsed;
+  let module =
+    preparsed.0.walk_ref(subpath, false).map_err(
+      |walk_err| match walk_err.kind {
+        WalkErrorKind::Private => {
+          unreachable!("visibility is not being checked here")
+        },
+        WalkErrorKind::Missing => ModuleNotFound {
+          file: i.extern_all(fpath),
+          subpath: (subpath.iter())
+            .take(walk_err.pos)
+            .map(|t| i.r(*t))
+            .cloned()
+            .collect(),
+        }
+        .rc(),
       },
-      WalkErrorKind::Missing => ModuleNotFound {
-        file: i.extern_vec(fpath),
-        subpath: (subpath_v.iter())
-          .take(walk_err.pos)
-          .map(|t| i.r(*t))
-          .cloned()
-          .collect(),
-      }
-      .rc(),
-    }
-  })?;
+    )?;
   let out = (module.items.iter())
     .filter(|(_, v)| v.exported)
     .map(|(k, _)| *k)
diff --git a/src/pipeline/project_tree/collect_ops/ops_for.rs b/src/pipeline/project_tree/collect_ops/ops_for.rs
index 8b97c8f..89ba9c1 100644
--- a/src/pipeline/project_tree/collect_ops/ops_for.rs
+++ b/src/pipeline/project_tree/collect_ops/ops_for.rs
@@ -19,7 +19,7 @@ fn tree_all_ops(
   ops.extend(module.items.keys().copied());
   for ent in module.items.values() {
     if let ModMember::Sub(m) = &ent.member {
-      tree_all_ops(m.as_ref(), ops);
+      tree_all_ops(m, ops);
     }
   }
 }
@@ -31,9 +31,9 @@ pub fn collect_ops_for(
   ops_cache: &ExportedOpsCache,
   i: &Interner,
 ) -> OpsResult {
-  let tree = &loaded[&i.i(file)].preparsed.0;
+  let tree = &loaded[file].preparsed.0;
   let mut ret = HashSet::new();
-  tree_all_ops(tree.as_ref(), &mut ret);
+  tree_all_ops(tree, &mut ret);
   tree.visit_all_imports(&mut |modpath, _module, import| {
     if let Some(n) = import.name {
       ret.insert(n);
diff --git a/src/pipeline/project_tree/const_tree.rs b/src/pipeline/project_tree/const_tree.rs
index c25cead..49cdf94 100644
--- a/src/pipeline/project_tree/const_tree.rs
+++ b/src/pipeline/project_tree/const_tree.rs
@@ -1,15 +1,14 @@
 use std::ops::Add;
-use std::rc::Rc;
 
 use hashbrown::HashMap;
 
 use super::{ProjectExt, ProjectModule, ProjectTree};
 use crate::ast::{Clause, Expr};
 use crate::foreign::{Atom, Atomic, ExternFn};
-use crate::interner::{Interner, Tok};
+use crate::interner::Tok;
 use crate::representations::location::Location;
 use crate::representations::tree::{ModEntry, ModMember, Module};
-use crate::representations::Primitive;
+use crate::representations::{Primitive, VName};
 use crate::utils::{pushed, Substack};
 
 /// A lightweight module tree that can be built declaratively by hand to
@@ -17,7 +16,7 @@ use crate::utils::{pushed, Substack};
 /// added convenience
 pub enum ConstTree {
   /// A function or constant
-  Const(Expr),
+  Const(Expr<VName>),
   /// A submodule
   Tree(HashMap<Tok<String>, ConstTree>),
 }
@@ -67,8 +66,7 @@ fn from_const_tree_rec(
   path: Substack<Tok<String>>,
   consts: HashMap<Tok<String>, ConstTree>,
   file: &[Tok<String>],
-  i: &Interner,
-) -> ProjectModule {
+) -> ProjectModule<VName> {
   let mut items = HashMap::new();
   let path_v = path.iter().rev_vec_clone();
   for (name, item) in consts {
@@ -76,17 +74,13 @@ fn from_const_tree_rec(
       exported: true,
       member: match item {
         ConstTree::Const(c) => ModMember::Item(c),
-        ConstTree::Tree(t) => ModMember::Sub(Rc::new(from_const_tree_rec(
-          path.push(name),
-          t,
-          file,
-          i,
-        ))),
+        ConstTree::Tree(t) =>
+          ModMember::Sub(from_const_tree_rec(path.push(name), t, file)),
       },
     });
   }
   let exports =
-    items.keys().map(|name| (*name, i.i(&pushed(&path_v, *name)))).collect();
+    items.keys().map(|name| (*name, pushed(&path_v, *name))).collect();
   Module {
     items,
     imports: vec![],
@@ -103,8 +97,7 @@ fn from_const_tree_rec(
 pub fn from_const_tree(
   consts: HashMap<Tok<String>, ConstTree>,
   file: &[Tok<String>],
-  i: &Interner,
-) -> ProjectTree {
-  let module = from_const_tree_rec(Substack::Bottom, consts, file, i);
-  ProjectTree(Rc::new(module))
+) -> ProjectTree<VName> {
+  let module = from_const_tree_rec(Substack::Bottom, consts, file);
+  ProjectTree(module)
 }
diff --git a/src/pipeline/project_tree/mod.rs b/src/pipeline/project_tree/mod.rs
index cc70436..7bc4459 100644
--- a/src/pipeline/project_tree/mod.rs
+++ b/src/pipeline/project_tree/mod.rs
@@ -26,5 +26,6 @@ pub use build_tree::{build_tree, split_path};
 pub use collect_ops::InjectedOperatorsFn;
 pub use const_tree::{from_const_tree, ConstTree};
 pub use tree::{
-  collect_consts, collect_rules, ProjectExt, ProjectModule, ProjectTree,
+  collect_consts, collect_rules, vname_to_sym_tree, ProjectExt, ProjectModule,
+  ProjectTree,
 };
diff --git a/src/pipeline/project_tree/normalize_imports.rs b/src/pipeline/project_tree/normalize_imports.rs
index e7465cf..7618215 100644
--- a/src/pipeline/project_tree/normalize_imports.rs
+++ b/src/pipeline/project_tree/normalize_imports.rs
@@ -6,7 +6,7 @@ use crate::representations::sourcefile::{
 };
 use crate::representations::tree::{ModMember, Module};
 use crate::utils::iter::box_once;
-use crate::utils::{BoxedIter, Substack};
+use crate::utils::{unwrap_or, BoxedIter, Substack};
 
 fn member_rec(
   // level
@@ -21,20 +21,12 @@ fn member_rec(
 ) -> Member {
   match member {
     Member::Namespace(Namespace { name, body }) => {
-      let prepmember = &preparsed.items[&name].member;
-      let subprep = if let ModMember::Sub(m) = prepmember {
-        m.clone()
-      } else {
+      let subprep = unwrap_or!(
+        &preparsed.items[&name].member => ModMember::Sub;
         unreachable!("This name must point to a namespace")
-      };
-      let new_body = entv_rec(
-        mod_stack.push(name),
-        subprep.as_ref(),
-        body,
-        path,
-        ops_cache,
-        i,
       );
+      let new_body =
+        entv_rec(mod_stack.push(name), subprep, body, path, ops_cache, i);
       Member::Namespace(Namespace { name, body: new_body })
     },
     any => any,
diff --git a/src/pipeline/project_tree/parse_file.rs b/src/pipeline/project_tree/parse_file.rs
index f483891..6916a77 100644
--- a/src/pipeline/project_tree/parse_file.rs
+++ b/src/pipeline/project_tree/parse_file.rs
@@ -4,40 +4,35 @@ use super::add_prelude::add_prelude;
 use super::collect_ops::{collect_ops_for, ExportedOpsCache};
 use super::normalize_imports::normalize_imports;
 use super::prefix::prefix;
-use crate::interner::{Interner, Sym};
+use crate::interner::{Interner, Tok};
 use crate::parse;
 use crate::pipeline::error::ProjectError;
 use crate::pipeline::source_loader::LoadedSourceTable;
 use crate::representations::sourcefile::{normalize_namespaces, FileEntry};
 
 pub fn parse_file(
-  path: Sym,
+  path: &[Tok<String>],
   loaded: &LoadedSourceTable,
   ops_cache: &ExportedOpsCache,
   i: &Interner,
   prelude: &[FileEntry],
 ) -> Result<Vec<FileEntry>, Rc<dyn ProjectError>> {
-  let ld = &loaded[&path];
+  let ld = &loaded[path];
   // let ops_cache = collect_ops::mk_cache(loaded, i);
-  let ops = collect_ops_for(&i.r(path)[..], loaded, ops_cache, i)?;
+  let ops = collect_ops_for(path, loaded, ops_cache, i)?;
   let ops_vec = ops.iter().map(|t| i.r(*t)).cloned().collect::<Vec<_>>();
   let ctx = parse::ParsingContext {
     interner: i,
     ops: &ops_vec,
-    file: Rc::new(i.extern_vec(path)),
+    file: Rc::new(i.extern_all(path)),
   };
   let entries = parse::parse(ld.text.as_str(), ctx)
     .expect("This error should have been caught during loading");
-  let with_prelude = add_prelude(entries, &i.r(path)[..], prelude);
-  let impnormalized = normalize_imports(
-    &ld.preparsed.0,
-    with_prelude,
-    &i.r(path)[..],
-    ops_cache,
-    i,
-  );
+  let with_prelude = add_prelude(entries, path, prelude);
+  let impnormalized =
+    normalize_imports(&ld.preparsed.0, with_prelude, path, ops_cache, i);
   let nsnormalized = normalize_namespaces(Box::new(impnormalized.into_iter()))
     .expect("This error should have been caught during preparsing");
-  let prefixed = prefix(nsnormalized, &i.r(path)[..], ops_cache, i);
+  let prefixed = prefix(nsnormalized, path, ops_cache, i);
   Ok(prefixed)
 }
diff --git a/src/pipeline/project_tree/prefix.rs b/src/pipeline/project_tree/prefix.rs
index 4192dfb..2c04d18 100644
--- a/src/pipeline/project_tree/prefix.rs
+++ b/src/pipeline/project_tree/prefix.rs
@@ -1,5 +1,3 @@
-use std::rc::Rc;
-
 use super::collect_ops::ExportedOpsCache;
 use crate::ast::{Constant, Rule};
 use crate::interner::{Interner, Tok};
@@ -16,14 +14,10 @@ fn member_rec(
   ops_cache: &ExportedOpsCache,
   i: &Interner,
 ) -> Member {
-  // let except = |op| imported.contains(&op);
-  let except = |_| false;
-  let prefix_v = path
-    .iter()
+  let prefix = (path.iter())
     .copied()
     .chain(mod_stack.iter().rev_vec_clone().into_iter())
     .collect::<Vec<_>>();
-  let prefix = i.i(&prefix_v);
   match data {
     Member::Namespace(Namespace { name, body }) => {
       let new_body = entv_rec(mod_stack.push(name), body, path, ops_cache, i);
@@ -31,16 +25,16 @@ fn member_rec(
     },
     Member::Constant(constant) => Member::Constant(Constant {
       name: constant.name,
-      value: constant.value.prefix(prefix, i, &except),
+      value: constant.value.prefix(&prefix, &|_| false),
     }),
     Member::Rule(rule) => Member::Rule(Rule {
       prio: rule.prio,
-      pattern: Rc::new(
-        rule.pattern.iter().map(|e| e.prefix(prefix, i, &except)).collect(),
-      ),
-      template: Rc::new(
-        rule.template.iter().map(|e| e.prefix(prefix, i, &except)).collect(),
-      ),
+      pattern: (rule.pattern.into_iter())
+        .map(|e| e.prefix(&prefix, &|_| false))
+        .collect(),
+      template: (rule.template.into_iter())
+        .map(|e| e.prefix(&prefix, &|_| false))
+        .collect(),
     }),
   }
 }
diff --git a/src/pipeline/project_tree/tree.rs b/src/pipeline/project_tree/tree.rs
index 98b2c3e..c2de388 100644
--- a/src/pipeline/project_tree/tree.rs
+++ b/src/pipeline/project_tree/tree.rs
@@ -1,28 +1,30 @@
 use std::ops::Add;
-use std::rc::Rc;
 
 use hashbrown::HashMap;
 
 use crate::ast::{Expr, Rule};
-use crate::interner::{Interner, Sym, Tok};
+use crate::interner::{Interner, Tok};
 use crate::representations::tree::{ModMember, Module};
+use crate::representations::NameLike;
+use crate::tree::ModEntry;
 use crate::utils::Substack;
+use crate::{Sym, VName};
 
 /// Additional data about a loaded module beyond the list of constants and
 /// submodules
 #[derive(Clone, Debug, Default)]
-pub struct ProjectExt {
+pub struct ProjectExt<N: NameLike> {
   /// Pairs each foreign token to the module it was imported from
-  pub imports_from: HashMap<Tok<String>, Sym>,
+  pub imports_from: HashMap<Tok<String>, N>,
   /// Pairs each exported token to its original full name
-  pub exports: HashMap<Tok<String>, Sym>,
+  pub exports: HashMap<Tok<String>, N>,
   /// All rules defined in this module, exported or not
-  pub rules: Vec<Rule>,
+  pub rules: Vec<Rule<N>>,
   /// Filename, if known, for error reporting
   pub file: Option<Vec<Tok<String>>>,
 }
 
-impl Add for ProjectExt {
+impl<N: NameLike> Add for ProjectExt<N> {
   type Output = Self;
 
   fn add(mut self, rhs: Self) -> Self::Output {
@@ -38,33 +40,36 @@ impl Add for ProjectExt {
 }
 
 /// A node in the tree describing the project
-pub type ProjectModule = Module<Expr, ProjectExt>;
+pub type ProjectModule<N> = Module<Expr<N>, ProjectExt<N>>;
 
 /// Module corresponding to the root of a project
 #[derive(Debug, Clone)]
-pub struct ProjectTree(pub Rc<ProjectModule>);
+pub struct ProjectTree<N: NameLike>(pub ProjectModule<N>);
 
-fn collect_rules_rec(bag: &mut Vec<Rule>, module: &ProjectModule) {
+fn collect_rules_rec<N: NameLike>(
+  bag: &mut Vec<Rule<N>>,
+  module: &ProjectModule<N>,
+) {
   bag.extend(module.extra.rules.iter().cloned());
   for item in module.items.values() {
     if let ModMember::Sub(module) = &item.member {
-      collect_rules_rec(bag, module.as_ref());
+      collect_rules_rec(bag, module);
     }
   }
 }
 
 /// Collect the complete list of rules to be used by the rule repository from
 /// the [ProjectTree]
-pub fn collect_rules(project: &ProjectTree) -> Vec<Rule> {
+pub fn collect_rules<N: NameLike>(project: &ProjectTree<N>) -> Vec<Rule<N>> {
   let mut rules = Vec::new();
-  collect_rules_rec(&mut rules, project.0.as_ref());
+  collect_rules_rec(&mut rules, &project.0);
   rules
 }
 
-fn collect_consts_rec(
+fn collect_consts_rec<N: NameLike>(
   path: Substack<Tok<String>>,
-  bag: &mut HashMap<Sym, Expr>,
-  module: &ProjectModule,
+  bag: &mut HashMap<Sym, Expr<N>>,
+  module: &ProjectModule<N>,
   i: &Interner,
 ) {
   for (key, entry) in module.items.iter() {
@@ -81,11 +86,59 @@ fn collect_consts_rec(
 }
 
 /// Extract the symbol table from a [ProjectTree]
-pub fn collect_consts(
-  project: &ProjectTree,
+pub fn collect_consts<N: NameLike>(
+  project: &ProjectTree<N>,
   i: &Interner,
-) -> HashMap<Sym, Expr> {
+) -> HashMap<Sym, Expr<N>> {
   let mut consts = HashMap::new();
-  collect_consts_rec(Substack::Bottom, &mut consts, project.0.as_ref(), i);
+  collect_consts_rec(Substack::Bottom, &mut consts, &project.0, i);
   consts
 }
+
+fn vname_to_sym_tree_rec(
+  tree: ProjectModule<VName>,
+  i: &Interner,
+) -> ProjectModule<Sym> {
+  let process_expr = |ex: Expr<VName>| ex.transform_names(&|n| i.i(&n));
+  ProjectModule {
+    imports: tree.imports,
+    items: (tree.items.into_iter())
+      .map(|(k, ModEntry { exported, member })| {
+        (k, ModEntry {
+          exported,
+          member: match member {
+            ModMember::Sub(module) =>
+              ModMember::Sub(vname_to_sym_tree_rec(module, i)),
+            ModMember::Item(ex) => ModMember::Item(process_expr(ex)),
+          },
+        })
+      })
+      .collect(),
+    extra: ProjectExt {
+      imports_from: (tree.extra.imports_from.into_iter())
+        .map(|(k, v)| (k, i.i(&v)))
+        .collect(),
+      exports: (tree.extra.exports.into_iter())
+        .map(|(k, v)| (k, i.i(&v)))
+        .collect(),
+      rules: (tree.extra.rules.into_iter())
+        .map(|Rule { pattern, prio, template }| Rule {
+          pattern: pattern.into_iter().map(process_expr).collect(),
+          prio,
+          template: template.into_iter().map(process_expr).collect(),
+        })
+        .collect(),
+      file: tree.extra.file,
+    },
+  }
+}
+
+/// Convert a flexible vname-based tree to a more rigid but faster symbol-based
+/// tree. The pipeline works with vnames, but the macro executor works with
+/// symbols.
+pub fn vname_to_sym_tree(
+  tree: ProjectTree<VName>,
+  i: &Interner,
+) -> ProjectTree<Sym> {
+  ProjectTree(vname_to_sym_tree_rec(tree.0, i))
+}
diff --git a/src/pipeline/source_loader/load_source.rs b/src/pipeline/source_loader/load_source.rs
index 115ee10..d1e4c24 100644
--- a/src/pipeline/source_loader/load_source.rs
+++ b/src/pipeline/source_loader/load_source.rs
@@ -3,22 +3,22 @@ use std::rc::Rc;
 
 use super::loaded_source::{LoadedSource, LoadedSourceTable};
 use super::preparse::preparse;
-use crate::interner::{Interner, Sym};
-use crate::pipeline::error::ProjectError;
-use crate::pipeline::file_loader::{load_text, IOResult, Loaded};
+use crate::interner::{Interner, Tok};
+use crate::pipeline::error::{ProjectError, UnexpectedDirectory};
+use crate::pipeline::file_loader::{IOResult, Loaded};
 use crate::pipeline::import_abs_path::import_abs_path;
 use crate::representations::sourcefile::FileEntry;
-use crate::utils::split_max_prefix;
+use crate::utils::{split_max_prefix, unwrap_or};
 
 /// Load the source at the given path or all within if it's a collection,
 /// and all sources imported from these.
 fn load_abs_path_rec(
-  abs_path: Sym,
+  abs_path: &[Tok<String>],
   table: &mut LoadedSourceTable,
   prelude: &[FileEntry],
   i: &Interner,
-  get_source: &impl Fn(Sym) -> IOResult,
-  is_injected_module: &impl Fn(Sym) -> bool,
+  get_source: &impl Fn(&[Tok<String>]) -> IOResult,
+  is_injected_module: &impl Fn(&[Tok<String>]) -> bool,
 ) -> Result<(), Rc<dyn ProjectError>> {
   // # Termination
   //
@@ -29,23 +29,26 @@ fn load_abs_path_rec(
   // contains no cycles.
 
   // Termination: exit if entry already visited
-  if table.contains_key(&abs_path) {
+  if table.contains_key(abs_path) {
     return Ok(());
   }
 
   // try splitting the path to file, swallowing any IO errors
-  let is_file = |sym| get_source(sym).map(|l| l.is_code()).unwrap_or(false);
-  let name_split = split_max_prefix(&i.r(abs_path)[..], &|p| is_file(i.i(p)));
+  let name_split = split_max_prefix(abs_path, &|p| {
+    get_source(p).map(|l| l.is_code()).unwrap_or(false)
+  });
   if let Some((filename, _)) = name_split {
     // if the filename is valid, load, preparse and record this file
-    let text = load_text(i.i(filename), &get_source, i)?;
+    let text = unwrap_or!(get_source(filename)? => Loaded::Code; {
+      return Err(UnexpectedDirectory { path: i.extern_all(filename) }.rc())
+    });
     let preparsed = preparse(
       filename.iter().map(|t| i.r(*t)).cloned().collect(),
       text.as_str(),
       prelude,
       i,
     )?;
-    table.insert(i.i(filename), LoadedSource {
+    table.insert(filename.to_vec(), LoadedSource {
       text,
       preparsed: preparsed.clone(),
     });
@@ -55,7 +58,7 @@ fn load_abs_path_rec(
         import_abs_path(filename, modpath, &import.nonglob_path(i), i)?;
       // recurse on imported module
       load_abs_path_rec(
-        i.i(&abs_pathv),
+        &abs_pathv,
         table,
         prelude,
         i,
@@ -70,20 +73,20 @@ fn load_abs_path_rec(
       Ok(Loaded::Code(_)) =>
         unreachable!("split_name returned None but the path is a file"),
       Err(e) => {
-        let parent = i.r(abs_path).split_last().expect("import path nonzero").1;
+        let parent = abs_path.split_last().expect("import path nonzero").1;
         // exit without error if it was injected, or raise any IO error that was
         // previously swallowed
-        return if is_injected_module(i.i(parent)) { Ok(()) } else { Err(e) };
+        return if is_injected_module(parent) { Ok(()) } else { Err(e) };
       },
     };
     // recurse on all files and folders within
     for item in coll.iter() {
-      let abs_subpath = (i.r(abs_path).iter())
+      let abs_subpath = (abs_path.iter())
         .copied()
         .chain(iter::once(i.i(item)))
         .collect::<Vec<_>>();
       load_abs_path_rec(
-        i.i(&abs_subpath),
+        &abs_subpath,
         table,
         prelude,
         i,
@@ -101,17 +104,17 @@ fn load_abs_path_rec(
 /// is_injected_module must return false for injected symbols, but may return
 /// true for parents of injected modules that are not directly part of the
 /// injected data (the ProjectTree doesn't make a distinction between the two)
-pub fn load_source(
-  targets: &[Sym],
+pub fn load_source<'a>(
+  targets: impl Iterator<Item = &'a [Tok<String>]>,
   prelude: &[FileEntry],
   i: &Interner,
-  get_source: &impl Fn(Sym) -> IOResult,
-  is_injected_module: &impl Fn(Sym) -> bool,
+  get_source: &impl Fn(&[Tok<String>]) -> IOResult,
+  is_injected_module: &impl Fn(&[Tok<String>]) -> bool,
 ) -> Result<LoadedSourceTable, Rc<dyn ProjectError>> {
   let mut table = LoadedSourceTable::new();
   for target in targets {
     load_abs_path_rec(
-      *target,
+      target,
       &mut table,
       prelude,
       i,
diff --git a/src/pipeline/source_loader/loaded_source.rs b/src/pipeline/source_loader/loaded_source.rs
index ae9fd43..9b72764 100644
--- a/src/pipeline/source_loader/loaded_source.rs
+++ b/src/pipeline/source_loader/loaded_source.rs
@@ -2,7 +2,7 @@ use std::collections::HashMap;
 use std::rc::Rc;
 
 use super::preparse::Preparsed;
-use crate::interner::Sym;
+use crate::representations::VName;
 
 #[derive(Debug)]
 pub struct LoadedSource {
@@ -10,4 +10,4 @@ pub struct LoadedSource {
   pub preparsed: Preparsed,
 }
 
-pub type LoadedSourceTable = HashMap<Sym, LoadedSource>;
+pub type LoadedSourceTable = HashMap<VName, LoadedSource>;
diff --git a/src/pipeline/source_loader/preparse.rs b/src/pipeline/source_loader/preparse.rs
index a622483..e9e826f 100644
--- a/src/pipeline/source_loader/preparse.rs
+++ b/src/pipeline/source_loader/preparse.rs
@@ -15,7 +15,7 @@ use crate::representations::sourcefile::{
 use crate::representations::tree::{ModEntry, ModMember, Module};
 
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct Preparsed(pub Rc<Module<(), ()>>);
+pub struct Preparsed(pub Module<(), ()>);
 
 /// Add an internal flat name if it does not exist yet
 fn add_intern<K: Eq + Hash>(map: &mut HashMap<K, ModEntry<(), ()>>, k: K) {
@@ -33,22 +33,18 @@ fn add_export<K: Eq + Hash>(map: &mut HashMap<K, ModEntry<(), ()>>, k: K) {
 }
 
 /// Convert source lines into a module
-fn to_module(
-  src: &[FileEntry],
-  prelude: &[FileEntry],
-  i: &Interner,
-) -> Rc<Module<(), ()>> {
+fn to_module(src: &[FileEntry], prelude: &[FileEntry]) -> Module<(), ()> {
   let all_src = || src.iter().chain(prelude.iter());
   let imports = imports(all_src()).cloned().collect::<Vec<_>>();
   let mut items = all_src()
     .filter_map(|ent| match ent {
       FileEntry::Internal(Member::Namespace(ns)) => {
-        let member = ModMember::Sub(to_module(&ns.body, prelude, i));
+        let member = ModMember::Sub(to_module(&ns.body, prelude));
         let entry = ModEntry { exported: false, member };
         Some((ns.name, entry))
       },
       FileEntry::Exported(Member::Namespace(ns)) => {
-        let member = ModMember::Sub(to_module(&ns.body, prelude, i));
+        let member = ModMember::Sub(to_module(&ns.body, prelude));
         let entry = ModEntry { exported: true, member };
         Some((ns.name, entry))
       },
@@ -70,20 +66,20 @@ fn to_module(
       FileEntry::Exported(Member::Constant(Constant { name, .. })) =>
         add_export(&mut items, *name),
       FileEntry::Internal(Member::Rule(rule)) => {
-        let names = rule.collect_single_names(i);
+        let names = rule.collect_single_names();
         for name in names {
           add_intern(&mut items, name)
         }
       },
       FileEntry::Exported(Member::Rule(rule)) => {
-        let names = rule.collect_single_names(i);
+        let names = rule.collect_single_names();
         for name in names {
           add_export(&mut items, name)
         }
       },
     }
   }
-  Rc::new(Module { imports, items, extra: () })
+  Module { imports, items, extra: () }
 }
 
 /// Preparse the module. At this stage, only the imports and
@@ -112,5 +108,5 @@ pub fn preparse(
       }
       .rc()
     })?;
-  Ok(Preparsed(to_module(&normalized, prelude, i)))
+  Ok(Preparsed(to_module(&normalized, prelude)))
 }
diff --git a/src/representations/ast.rs b/src/representations/ast.rs
index 451bc58..e5e1507 100644
--- a/src/representations/ast.rs
+++ b/src/representations/ast.rs
@@ -1,9 +1,7 @@
-//! Datastructures representing syntax as written
+//! Datastructures representing the units of macro execution
 //!
-//! These structures are produced by the parser, processed by the macro
-//! executor, and then converted to other usable formats. This module is public
-//! in order to allow users to define injected libraries programmatically,
-//! although going through the parser is usually preferable.
+//! These structures are produced by the pipeline, processed by the macro
+//! executor, and then converted to other usable formats.
 
 use std::hash::Hash;
 use std::rc::Rc;
@@ -12,55 +10,62 @@ use itertools::Itertools;
 use ordered_float::NotNan;
 
 use super::location::Location;
+use super::namelike::{NameLike, VName};
 use super::primitive::Primitive;
-use crate::interner::{InternedDisplay, Interner, Sym, Tok};
-use crate::utils::Substack;
+use crate::interner::{InternedDisplay, Interner, Tok};
+use crate::utils::{map_rc, Substack};
 
 /// A [Clause] with associated metadata
 #[derive(Clone, Debug, PartialEq)]
-pub struct Expr {
+pub struct Expr<N: NameLike> {
   /// The actual value
-  pub value: Clause,
+  pub value: Clause<N>,
   /// Information about the code that produced this value
   pub location: Location,
 }
 
-impl Expr {
+impl<N: NameLike> Expr<N> {
   /// Obtain the contained clause
-  pub fn into_clause(self) -> Clause {
+  pub fn into_clause(self) -> Clause<N> {
     self.value
   }
 
   /// Call the function on every name in this expression
-  pub fn visit_names(&self, binds: Substack<Sym>, cb: &mut impl FnMut(Sym)) {
+  pub fn visit_names(&self, binds: Substack<&N>, cb: &mut impl FnMut(&N)) {
     let Expr { value, .. } = self;
     value.visit_names(binds, cb);
   }
 
   /// Process all names with the given mapper.
   /// Return a new object if anything was processed
-  pub fn map_names(&self, pred: &impl Fn(Sym) -> Option<Sym>) -> Option<Self> {
+  pub fn map_names(&self, pred: &impl Fn(&N) -> Option<N>) -> Option<Self> {
     Some(Self {
       value: self.value.map_names(pred)?,
       location: self.location.clone(),
     })
   }
 
+  /// Transform from one name system to another
+  pub fn transform_names<O: NameLike>(self, pred: &impl Fn(N) -> O) -> Expr<O> {
+    Expr { value: self.value.transform_names(pred), location: self.location }
+  }
+}
+
+impl Expr<VName> {
   /// Add the specified prefix to every Name
   pub fn prefix(
     &self,
-    prefix: Sym,
-    i: &Interner,
+    prefix: &[Tok<String>],
     except: &impl Fn(Tok<String>) -> bool,
   ) -> Self {
     Self {
-      value: self.value.prefix(prefix, i, except),
+      value: self.value.prefix(prefix, except),
       location: self.location.clone(),
     }
   }
 }
 
-impl InternedDisplay for Expr {
+impl<N: NameLike> InternedDisplay for Expr<N> {
   fn fmt_i(
     &self,
     f: &mut std::fmt::Formatter<'_>,
@@ -116,23 +121,23 @@ impl InternedDisplay for Placeholder {
 
 /// An S-expression as read from a source file
 #[derive(Debug, PartialEq, Clone)]
-pub enum Clause {
+pub enum Clause<N: NameLike> {
   /// A primitive
   P(Primitive),
   /// A c-style name or an operator, eg. `+`, `i`, `foo::bar`
-  Name(Sym),
-  /// A parenthesized exmrc_empty_slice()pression
+  Name(N),
+  /// A parenthesized expression
   /// eg. `(print out "hello")`, `[1, 2, 3]`, `{Some(t) => t}`
-  S(char, Rc<Vec<Expr>>),
+  S(char, Rc<Vec<Expr<N>>>),
   /// A function expression, eg. `\x. x + 1`
-  Lambda(Rc<Expr>, Rc<Vec<Expr>>),
+  Lambda(Rc<Expr<N>>, Rc<Vec<Expr<N>>>),
   /// A placeholder for macros, eg. `$name`, `...$body`, `...$lhs:1`
   Placeh(Placeholder),
 }
 
-impl Clause {
+impl<N: NameLike> Clause<N> {
   /// Extract the expressions from an auto, lambda or S
-  pub fn body(&self) -> Option<Rc<Vec<Expr>>> {
+  pub fn body(&self) -> Option<Rc<Vec<Expr<N>>>> {
     match self {
       Self::Lambda(_, body) | Self::S(_, body) => Some(body.clone()),
       _ => None,
@@ -140,7 +145,7 @@ impl Clause {
   }
 
   /// Convert with identical meaning
-  pub fn into_expr(self) -> Expr {
+  pub fn into_expr(self) -> Expr<N> {
     if let Self::S('(', body) = &self {
       if body.len() == 1 {
         body[0].clone()
@@ -153,7 +158,7 @@ impl Clause {
   }
 
   /// Convert with identical meaning
-  pub fn from_exprs(exprs: &[Expr]) -> Option<Clause> {
+  pub fn from_exprs(exprs: &[Expr<N>]) -> Option<Self> {
     if exprs.is_empty() {
       None
     } else if exprs.len() == 1 {
@@ -163,7 +168,7 @@ impl Clause {
     }
   }
   /// Convert with identical meaning
-  pub fn from_exprv(exprv: &Rc<Vec<Expr>>) -> Option<Clause> {
+  pub fn from_exprv(exprv: &Rc<Vec<Expr<N>>>) -> Option<Clause<N>> {
     if exprv.len() < 2 {
       Self::from_exprs(exprv)
     } else {
@@ -175,12 +180,12 @@ impl Clause {
   /// It also finds a lot of things that aren't names, such as all
   /// bound parameters. Generally speaking, this is not a very
   /// sophisticated search.
-  pub fn visit_names(&self, binds: Substack<Sym>, cb: &mut impl FnMut(Sym)) {
+  pub fn visit_names(&self, binds: Substack<&N>, cb: &mut impl FnMut(&N)) {
     match self {
       Clause::Lambda(arg, body) => {
         arg.visit_names(binds, cb);
         let new_binds =
-          if let Clause::Name(n) = arg.value { binds.push(n) } else { binds };
+          if let Clause::Name(n) = &arg.value { binds.push(n) } else { binds };
         for x in body.iter() {
           x.visit_names(new_binds, cb)
         }
@@ -190,8 +195,8 @@ impl Clause {
           x.visit_names(binds, cb)
         },
       Clause::Name(name) =>
-        if binds.iter().all(|x| x != name) {
-          cb(*name)
+        if binds.iter().all(|x| x != &name) {
+          cb(name)
         },
       _ => (),
     }
@@ -199,10 +204,10 @@ impl Clause {
 
   /// Process all names with the given mapper.
   /// Return a new object if anything was processed
-  pub fn map_names(&self, pred: &impl Fn(Sym) -> Option<Sym>) -> Option<Self> {
+  pub fn map_names(&self, pred: &impl Fn(&N) -> Option<N>) -> Option<Self> {
     match self {
       Clause::P(_) | Clause::Placeh(_) => None,
-      Clause::Name(name) => pred(*name).map(Clause::Name),
+      Clause::Name(name) => pred(name).map(Clause::Name),
       Clause::S(c, body) => {
         let mut any_some = false;
         let new_body = body
@@ -238,29 +243,49 @@ impl Clause {
     }
   }
 
+  /// Transform from one name representation to another
+  pub fn transform_names<O: NameLike>(
+    self,
+    pred: &impl Fn(N) -> O,
+  ) -> Clause<O> {
+    match self {
+      Self::Name(n) => Clause::Name(pred(n)),
+      Self::Placeh(p) => Clause::Placeh(p),
+      Self::P(p) => Clause::P(p),
+      Self::Lambda(n, b) => Clause::Lambda(
+        map_rc(n, |n| n.transform_names(pred)),
+        map_rc(b, |b| b.into_iter().map(|e| e.transform_names(pred)).collect()),
+      ),
+      Self::S(c, b) => Clause::S(
+        c,
+        map_rc(b, |b| b.into_iter().map(|e| e.transform_names(pred)).collect()),
+      ),
+    }
+  }
+}
+
+impl Clause<VName> {
   /// Add the specified prefix to every Name
   pub fn prefix(
     &self,
-    prefix: Sym,
-    i: &Interner,
+    prefix: &[Tok<String>],
     except: &impl Fn(Tok<String>) -> bool,
   ) -> Self {
     self
       .map_names(&|name| {
-        let old = i.r(name);
-        if except(old[0]) {
+        if except(name[0]) {
           return None;
         }
-        let mut new = i.r(prefix).clone();
-        new.extend_from_slice(old);
-        Some(i.i(&new))
+        let mut new = prefix.to_vec();
+        new.extend_from_slice(name);
+        Some(new)
       })
       .unwrap_or_else(|| self.clone())
   }
 }
 
-fn fmt_expr_seq<'a>(
-  it: &mut impl Iterator<Item = &'a Expr>,
+fn fmt_expr_seq<'a, N: NameLike>(
+  it: &mut impl Iterator<Item = &'a Expr<N>>,
   f: &mut std::fmt::Formatter<'_>,
   i: &Interner,
 ) -> std::fmt::Result {
@@ -273,19 +298,7 @@ fn fmt_expr_seq<'a>(
   Ok(())
 }
 
-pub(crate) fn fmt_name(
-  name: Sym,
-  f: &mut std::fmt::Formatter,
-  i: &Interner,
-) -> std::fmt::Result {
-  let strings = i.r(name).iter().map(|t| i.r(*t).as_str());
-  for el in itertools::intersperse(strings, "::") {
-    write!(f, "{}", el)?
-  }
-  Ok(())
-}
-
-impl InternedDisplay for Clause {
+impl<N: NameLike> InternedDisplay for Clause<N> {
   fn fmt_i(
     &self,
     f: &mut std::fmt::Formatter<'_>,
@@ -293,7 +306,7 @@ impl InternedDisplay for Clause {
   ) -> std::fmt::Result {
     match self {
       Self::P(p) => write!(f, "{:?}", p),
-      Self::Name(name) => fmt_name(*name, f, i),
+      Self::Name(name) => write!(f, "{}", name.to_strv(i).join("::")),
       Self::S(del, items) => {
         f.write_str(&del.to_string())?;
         fmt_expr_seq(&mut items.iter(), f, i)?;
@@ -317,54 +330,47 @@ impl InternedDisplay for Clause {
 
 /// A substitution rule as read from the source
 #[derive(Debug, Clone, PartialEq)]
-pub struct Rule {
+pub struct Rule<N: NameLike> {
   /// Tree fragment in the source code that activates this rule
-  pub pattern: Rc<Vec<Expr>>,
+  pub pattern: Vec<Expr<N>>,
   /// Influences the order in which rules are checked
   pub prio: NotNan<f64>,
   /// Tree fragment generated by this rule
-  pub template: Rc<Vec<Expr>>,
+  pub template: Vec<Expr<N>>,
 }
 
-impl Rule {
-  /// Return a list of all names that don't contain a namespace separator `::`.
-  /// These are exported when the rule is exported
-  pub fn collect_single_names(&self, i: &Interner) -> Vec<Tok<String>> {
-    let mut names = Vec::new();
-    for e in self.pattern.iter() {
-      e.visit_names(Substack::Bottom, &mut |tok| {
-        let ns_name = i.r(tok);
-        let (name, excess) =
-          ns_name.split_first().expect("Namespaced name must not be empty");
-        if !excess.is_empty() {
-          return;
-        }
-        names.push(*name)
-      });
-    }
-    names
-  }
-
+impl Rule<VName> {
   /// Namespace all tokens in the rule
   pub fn prefix(
     &self,
-    prefix: Sym,
-    i: &Interner,
+    prefix: &[Tok<String>],
     except: &impl Fn(Tok<String>) -> bool,
   ) -> Self {
     Self {
       prio: self.prio,
-      pattern: Rc::new(
-        self.pattern.iter().map(|e| e.prefix(prefix, i, except)).collect(),
-      ),
-      template: Rc::new(
-        self.template.iter().map(|e| e.prefix(prefix, i, except)).collect(),
-      ),
+      pattern: self.pattern.iter().map(|e| e.prefix(prefix, except)).collect(),
+      template: (self.template.iter())
+        .map(|e| e.prefix(prefix, except))
+        .collect(),
     }
   }
+
+  /// Return a list of all names that don't contain a namespace separator `::`.
+  /// These are exported when the rule is exported
+  pub fn collect_single_names(&self) -> Vec<Tok<String>> {
+    let mut names = Vec::new();
+    for e in self.pattern.iter() {
+      e.visit_names(Substack::Bottom, &mut |ns_name| {
+        if ns_name.len() == 1 {
+          names.push(ns_name[0])
+        }
+      });
+    }
+    names
+  }
 }
 
-impl InternedDisplay for Rule {
+impl<N: NameLike> InternedDisplay for Rule<N> {
   fn fmt_i(
     &self,
     f: &mut std::fmt::Formatter<'_>,
@@ -389,7 +395,7 @@ pub struct Constant {
   /// Used to reference the constant
   pub name: Tok<String>,
   /// The constant value inserted where the name is found
-  pub value: Expr,
+  pub value: Expr<VName>,
 }
 
 impl InternedDisplay for Constant {
diff --git a/src/representations/ast_to_interpreted.rs b/src/representations/ast_to_interpreted.rs
index 6e208a8..49fbc06 100644
--- a/src/representations/ast_to_interpreted.rs
+++ b/src/representations/ast_to_interpreted.rs
@@ -1,4 +1,5 @@
 use super::{ast, ast_to_postmacro, interpreted, postmacro_to_interpreted};
+use crate::Sym;
 
 #[allow(unused)]
 pub type AstError = ast_to_postmacro::Error;
@@ -6,7 +7,7 @@ pub type AstError = ast_to_postmacro::Error;
 /// Attempt to convert the AST processed by macros into an executable format
 #[allow(unused)]
 pub fn ast_to_interpreted(
-  ast: &ast::Expr,
+  ast: &ast::Expr<Sym>,
 ) -> Result<interpreted::ExprInst, AstError> {
   let pmtree = ast_to_postmacro::expr(ast)?;
   Ok(postmacro_to_interpreted::expr(&pmtree))
diff --git a/src/representations/ast_to_postmacro.rs b/src/representations/ast_to_postmacro.rs
index 152d484..d47b97a 100644
--- a/src/representations/ast_to_postmacro.rs
+++ b/src/representations/ast_to_postmacro.rs
@@ -3,8 +3,8 @@ use std::rc::Rc;
 
 use super::location::Location;
 use super::{ast, postmacro};
-use crate::interner::Sym;
 use crate::utils::Substack;
+use crate::Sym;
 
 #[derive(Clone)]
 pub enum Error {
@@ -42,7 +42,7 @@ impl Display for Error {
 }
 
 /// Try to convert an expression from AST format to typed lambda
-pub fn expr(expr: &ast::Expr) -> Result<postmacro::Expr, Error> {
+pub fn expr(expr: &ast::Expr<Sym>) -> Result<postmacro::Expr, Error> {
   expr_rec(expr, Context::new())
 }
 
@@ -66,7 +66,7 @@ impl<'a> Context<'a> {
 
 /// Process an expression sequence
 fn exprv_rec<'a>(
-  v: &'a [ast::Expr],
+  v: &'a [ast::Expr<Sym>],
   ctx: Context<'a>,
 ) -> Result<postmacro::Expr, Error> {
   let (last, rest) = v.split_last().ok_or(Error::EmptyS)?;
@@ -81,7 +81,7 @@ fn exprv_rec<'a>(
 
 /// Process an expression
 fn expr_rec<'a>(
-  ast::Expr { value, location }: &'a ast::Expr,
+  ast::Expr { value, location }: &'a ast::Expr<Sym>,
   ctx: Context<'a>,
 ) -> Result<postmacro::Expr, Error> {
   if let ast::Clause::S(paren, body) = value {
@@ -98,7 +98,7 @@ fn expr_rec<'a>(
 
 /// Process a clause
 fn clause_rec<'a>(
-  cls: &'a ast::Clause,
+  cls: &'a ast::Clause<Sym>,
   ctx: Context<'a>,
 ) -> Result<postmacro::Clause, Error> {
   match cls {
diff --git a/src/representations/interpreted.rs b/src/representations/interpreted.rs
index b75db9b..3a0a220 100644
--- a/src/representations/interpreted.rs
+++ b/src/representations/interpreted.rs
@@ -11,8 +11,9 @@ use super::location::Location;
 use super::path_set::PathSet;
 use super::primitive::Primitive;
 use super::Literal;
-use crate::interner::{InternedDisplay, Sym};
+use crate::interner::InternedDisplay;
 use crate::utils::sym2string;
+use crate::Sym;
 
 // TODO: implement Debug, Eq and Hash with cycle detection
 
diff --git a/src/representations/mod.rs b/src/representations/mod.rs
index f17e123..f4c7eb8 100644
--- a/src/representations/mod.rs
+++ b/src/representations/mod.rs
@@ -4,6 +4,7 @@ pub mod ast_to_postmacro;
 pub mod interpreted;
 pub mod literal;
 pub mod location;
+mod namelike;
 pub mod path_set;
 pub mod postmacro;
 pub mod postmacro_to_interpreted;
@@ -13,5 +14,6 @@ pub mod tree;
 
 pub use literal::Literal;
 pub use location::Location;
+pub use namelike::{NameLike, Sym, VName};
 pub use path_set::PathSet;
 pub use primitive::Primitive;
diff --git a/src/representations/namelike.rs b/src/representations/namelike.rs
new file mode 100644
index 0000000..c3aec57
--- /dev/null
+++ b/src/representations/namelike.rs
@@ -0,0 +1,34 @@
+use crate::interner::{Interner, Tok};
+
+/// A mutable representation of a namespaced identifier.
+///
+/// These names may be relative or otherwise partially processed.
+///
+/// See also [Sym]
+pub type VName = Vec<Tok<String>>;
+
+/// An interned representation of a namespaced identifier.
+///
+/// These names are always absolute.
+///
+/// See also [VName]
+pub type Sym = Tok<Vec<Tok<String>>>;
+
+/// An abstraction over tokenized vs non-tokenized names so that they can be
+/// handled together in datastructures
+pub trait NameLike: 'static + Clone + Eq {
+  /// Fully resolve the name for printing
+  fn to_strv(&self, i: &Interner) -> Vec<String>;
+}
+
+impl NameLike for Sym {
+  fn to_strv(&self, i: &Interner) -> Vec<String> {
+    i.extern_vec(*self)
+  }
+}
+
+impl NameLike for VName {
+  fn to_strv(&self, i: &Interner) -> Vec<String> {
+    i.extern_all(self)
+  }
+}
diff --git a/src/representations/path_set.rs b/src/representations/path_set.rs
index ea5a278..5edfcb5 100644
--- a/src/representations/path_set.rs
+++ b/src/representations/path_set.rs
@@ -2,7 +2,7 @@ use std::fmt::Debug;
 use std::ops::Add;
 use std::rc::Rc;
 
-use crate::utils::Side;
+use crate::utils::{rc_to_owned, Side};
 
 /// A branching path selecting some placeholders (but at least one) in a Lambda
 /// expression
@@ -41,8 +41,7 @@ impl Add<Side> for PathSet {
   type Output = Self;
   fn add(self, rhs: Side) -> Self::Output {
     let PathSet { steps, next } = self;
-    let mut new_steps =
-      Rc::try_unwrap(steps).unwrap_or_else(|rc| rc.as_ref().clone());
+    let mut new_steps = rc_to_owned(steps);
     new_steps.insert(0, rhs);
     Self { steps: Rc::new(new_steps), next }
   }
diff --git a/src/representations/postmacro.rs b/src/representations/postmacro.rs
index 5329360..498aa2d 100644
--- a/src/representations/postmacro.rs
+++ b/src/representations/postmacro.rs
@@ -3,8 +3,8 @@ use std::rc::Rc;
 
 use super::location::Location;
 use super::primitive::Primitive;
-use crate::interner::Sym;
 use crate::utils::string_from_charset;
+use crate::Sym;
 
 /// Indicates whether either side needs to be wrapped. Syntax whose end is
 /// ambiguous on that side must use parentheses, or forward the flag
diff --git a/src/representations/sourcefile.rs b/src/representations/sourcefile.rs
index 451bb55..0d82a50 100644
--- a/src/representations/sourcefile.rs
+++ b/src/representations/sourcefile.rs
@@ -3,9 +3,11 @@ use std::iter;
 
 use itertools::{Either, Itertools};
 
+use super::namelike::VName;
 use crate::ast::{Constant, Rule};
-use crate::interner::{Interner, Sym, Tok};
+use crate::interner::{Interner, Tok};
 use crate::utils::{unwrap_or, BoxedIter};
+use crate::Sym;
 
 /// An import pointing at another module, either specifying the symbol to be
 /// imported or importing all available symbols with a globstar (*)
@@ -50,7 +52,7 @@ pub struct Namespace {
 pub enum Member {
   /// A substitution rule. Rules apply even when they're not in scope, if the
   /// absolute names are present eg. because they're produced by other rules
-  Rule(Rule),
+  Rule(Rule<VName>),
   /// A constant (or function) associated with a name
   Constant(Constant),
   /// A prefixed set of other entries
diff --git a/src/representations/tree.rs b/src/representations/tree.rs
index b59665d..860a9d4 100644
--- a/src/representations/tree.rs
+++ b/src/representations/tree.rs
@@ -2,8 +2,8 @@
 //!
 //! Used by various stages of the pipeline with different parameters
 use std::ops::Add;
-use std::rc::Rc;
 
+use duplicate::duplicate_item;
 use hashbrown::HashMap;
 
 use super::sourcefile::Import;
@@ -16,7 +16,7 @@ pub enum ModMember<TItem: Clone, TExt: Clone> {
   /// Arbitrary data
   Item(TItem),
   /// A child module
-  Sub(Rc<Module<TItem, TExt>>),
+  Sub(Module<TItem, TExt>),
 }
 
 /// Data about a name in a [Module]
@@ -61,18 +61,25 @@ pub struct WalkError {
 pub type ModPath<'a> = Substack<'a, Tok<String>>;
 
 impl<TItem: Clone, TExt: Clone> Module<TItem, TExt> {
-  /// Return the module at the end of the given path.
-  pub fn walk(
-    self: &Rc<Self>,
+  /// Return the module at the end of the given path
+  #[allow(clippy::needless_arbitrary_self_type)] // duplicate
+  #[duplicate_item(
+    method      reference(type) dereference(expr) map_method;
+    [walk]      [type]          [expr]            [remove];
+    [walk_ref]  [&type]         [*expr]           [get];
+    [walk_mut]  [&mut type]     [*expr]           [get_mut];
+  )]
+  pub fn method(
+    self: reference([Self]),
     path: &[Tok<String>],
     require_exported: bool,
-  ) -> Result<Rc<Self>, WalkError> {
+  ) -> Result<reference([Self]), WalkError> {
     let mut cur = self;
     for (pos, step) in path.iter().enumerate() {
       if let Some(ModEntry { member: ModMember::Sub(next), exported }) =
-        cur.items.get(step)
+        cur.items.map_method(step)
       {
-        if require_exported && !exported {
+        if require_exported && !dereference([exported]) {
           return Err(WalkError { pos, kind: WalkErrorKind::Private });
         }
         cur = next
@@ -80,7 +87,7 @@ impl<TItem: Clone, TExt: Clone> Module<TItem, TExt> {
         return Err(WalkError { pos, kind: WalkErrorKind::Missing });
       }
     }
-    Ok(cur.clone())
+    Ok(cur)
   }
 
   fn visit_all_imports_rec<E>(
@@ -118,21 +125,16 @@ impl<TItem: Clone, TExt: Clone> Module<TItem, TExt> {
     let mut new_items = HashMap::new();
     for (key, right) in items {
       // if both contain a submodule
-      if let Some(left) = self.items.remove(&key) {
-        if let ModMember::Sub(rsub) = &right.member {
-          if let ModMember::Sub(lsub) = &left.member {
-            // merge them with rhs exportedness
-            let new_mod = lsub.as_ref().clone().overlay(rsub.as_ref().clone());
-            new_items.insert(key, ModEntry {
-              exported: right.exported,
-              member: ModMember::Sub(Rc::new(new_mod)),
-            });
-            continue;
-          }
-        }
-      }
-      // otherwise right shadows left
-      new_items.insert(key, right);
+      match (self.items.remove(&key), right) {
+        (
+          Some(ModEntry { member: ModMember::Sub(lsub), .. }),
+          ModEntry { member: ModMember::Sub(rsub), exported },
+        ) => new_items.insert(key, ModEntry {
+          exported,
+          member: ModMember::Sub(lsub.overlay(rsub)),
+        }),
+        (_, right) => new_items.insert(key, right),
+      };
     }
     new_items.extend(self.items.into_iter());
     self.imports.extend(imports.into_iter());
diff --git a/src/rule/matcher.rs b/src/rule/matcher.rs
index ec45a22..c57ce3d 100644
--- a/src/rule/matcher.rs
+++ b/src/rule/matcher.rs
@@ -2,12 +2,15 @@ use std::rc::Rc;
 
 use super::state::State;
 use crate::ast::Expr;
+use crate::Sym;
+
+pub type RuleExpr = Expr<Sym>;
 
 /// Cacheable optimized structures for matching patterns on slices. This is
 /// injected to allow experimentation in the matcher implementation.
 pub trait Matcher {
   /// Build matcher for a pattern
-  fn new(pattern: Rc<Vec<Expr>>) -> Self;
+  fn new(pattern: Rc<Vec<RuleExpr>>) -> Self;
   /// Apply matcher to a token sequence
-  fn apply<'a>(&self, source: &'a [Expr]) -> Option<State<'a>>;
+  fn apply<'a>(&self, source: &'a [RuleExpr]) -> Option<State<'a>>;
 }
diff --git a/src/rule/matcher_vectree/any_match.rs b/src/rule/matcher_vectree/any_match.rs
index 812469d..cfb86b2 100644
--- a/src/rule/matcher_vectree/any_match.rs
+++ b/src/rule/matcher_vectree/any_match.rs
@@ -1,12 +1,12 @@
 use super::scal_match::scalv_match;
 use super::shared::AnyMatcher;
 use super::vec_match::vec_match;
-use crate::ast::Expr;
+use crate::rule::matcher::RuleExpr;
 use crate::rule::state::State;
 
 pub fn any_match<'a>(
   matcher: &AnyMatcher,
-  seq: &'a [Expr],
+  seq: &'a [RuleExpr],
 ) -> Option<State<'a>> {
   match matcher {
     AnyMatcher::Scalar(scalv) => scalv_match(scalv, seq),
diff --git a/src/rule/matcher_vectree/build.rs b/src/rule/matcher_vectree/build.rs
index 39b8adf..a19ba92 100644
--- a/src/rule/matcher_vectree/build.rs
+++ b/src/rule/matcher_vectree/build.rs
@@ -1,16 +1,18 @@
 use itertools::Itertools;
 
 use super::shared::{AnyMatcher, ScalMatcher, VecMatcher};
-use crate::ast::{Clause, Expr, PHClass, Placeholder};
+use crate::ast::{Clause, PHClass, Placeholder};
 use crate::interner::Tok;
+use crate::rule::matcher::RuleExpr;
 use crate::rule::vec_attrs::vec_attrs;
 use crate::utils::Side;
 
-pub type MaxVecSplit<'a> = (&'a [Expr], (Tok<String>, u64, bool), &'a [Expr]);
+pub type MaxVecSplit<'a> =
+  (&'a [RuleExpr], (Tok<String>, u64, bool), &'a [RuleExpr]);
 
 /// Derive the details of the central vectorial and the two sides from a
 /// slice of Expr's
-fn split_at_max_vec(pattern: &[Expr]) -> Option<MaxVecSplit> {
+fn split_at_max_vec(pattern: &[RuleExpr]) -> Option<MaxVecSplit> {
   let rngidx = pattern.iter().position_max_by_key(|expr| {
     vec_attrs(expr).map(|attrs| attrs.1 as i64).unwrap_or(-1)
   })?;
@@ -21,11 +23,11 @@ fn split_at_max_vec(pattern: &[Expr]) -> Option<MaxVecSplit> {
   vec_attrs(placeh).map(|attrs| (left, attrs, right))
 }
 
-fn scal_cnt<'a>(iter: impl Iterator<Item = &'a Expr>) -> usize {
+fn scal_cnt<'a>(iter: impl Iterator<Item = &'a RuleExpr>) -> usize {
   iter.take_while(|expr| vec_attrs(expr).is_none()).count()
 }
 
-pub fn mk_any(pattern: &[Expr]) -> AnyMatcher {
+pub fn mk_any(pattern: &[RuleExpr]) -> AnyMatcher {
   let left_split = scal_cnt(pattern.iter());
   if pattern.len() <= left_split {
     return AnyMatcher::Scalar(mk_scalv(pattern));
@@ -41,12 +43,12 @@ pub fn mk_any(pattern: &[Expr]) -> AnyMatcher {
 }
 
 /// Pattern MUST NOT contain vectorial placeholders
-fn mk_scalv(pattern: &[Expr]) -> Vec<ScalMatcher> {
+fn mk_scalv(pattern: &[RuleExpr]) -> Vec<ScalMatcher> {
   pattern.iter().map(mk_scalar).collect()
 }
 
 /// Pattern MUST start and end with a vectorial placeholder
-fn mk_vec(pattern: &[Expr]) -> VecMatcher {
+fn mk_vec(pattern: &[RuleExpr]) -> VecMatcher {
   debug_assert!(!pattern.is_empty(), "pattern cannot be empty");
   debug_assert!(
     pattern.first().map(vec_attrs).is_some(),
@@ -97,7 +99,7 @@ fn mk_vec(pattern: &[Expr]) -> VecMatcher {
 }
 
 /// Pattern MUST NOT be a vectorial placeholder
-fn mk_scalar(pattern: &Expr) -> ScalMatcher {
+fn mk_scalar(pattern: &RuleExpr) -> ScalMatcher {
   match &pattern.value {
     Clause::P(p) => ScalMatcher::P(p.clone()),
     Clause::Name(n) => ScalMatcher::Name(*n),
diff --git a/src/rule/matcher_vectree/scal_match.rs b/src/rule/matcher_vectree/scal_match.rs
index 8e19539..2b6c499 100644
--- a/src/rule/matcher_vectree/scal_match.rs
+++ b/src/rule/matcher_vectree/scal_match.rs
@@ -1,11 +1,12 @@
 use super::any_match::any_match;
 use super::shared::ScalMatcher;
-use crate::ast::{Clause, Expr};
+use crate::ast::Clause;
+use crate::rule::matcher::RuleExpr;
 use crate::rule::state::{State, StateEntry};
 
 pub fn scal_match<'a>(
   matcher: &ScalMatcher,
-  expr: &'a Expr,
+  expr: &'a RuleExpr,
 ) -> Option<State<'a>> {
   match (matcher, &expr.value) {
     (ScalMatcher::P(p1), Clause::P(p2)) if p1 == p2 => Some(State::new()),
@@ -25,7 +26,7 @@ pub fn scal_match<'a>(
 
 pub fn scalv_match<'a>(
   matchers: &[ScalMatcher],
-  seq: &'a [Expr],
+  seq: &'a [RuleExpr],
 ) -> Option<State<'a>> {
   if seq.len() != matchers.len() {
     return None;
diff --git a/src/rule/matcher_vectree/shared.rs b/src/rule/matcher_vectree/shared.rs
index ac1d339..bc67a4d 100644
--- a/src/rule/matcher_vectree/shared.rs
+++ b/src/rule/matcher_vectree/shared.rs
@@ -3,12 +3,12 @@ use std::rc::Rc;
 
 use super::any_match::any_match;
 use super::build::mk_any;
-use crate::ast::Expr;
-use crate::interner::{InternedDisplay, Interner, Sym, Tok};
+use crate::interner::{InternedDisplay, Interner, Tok};
 use crate::representations::Primitive;
-use crate::rule::matcher::Matcher;
+use crate::rule::matcher::{Matcher, RuleExpr};
 use crate::rule::state::State;
 use crate::utils::{sym2string, unwrap_or, Side};
+use crate::Sym;
 
 pub enum ScalMatcher {
   P(Primitive),
@@ -54,11 +54,11 @@ pub enum AnyMatcher {
   Vec { left: Vec<ScalMatcher>, mid: VecMatcher, right: Vec<ScalMatcher> },
 }
 impl Matcher for AnyMatcher {
-  fn new(pattern: Rc<Vec<Expr>>) -> Self {
+  fn new(pattern: Rc<Vec<RuleExpr>>) -> Self {
     mk_any(&pattern)
   }
 
-  fn apply<'a>(&self, source: &'a [Expr]) -> Option<State<'a>> {
+  fn apply<'a>(&self, source: &'a [RuleExpr]) -> Option<State<'a>> {
     any_match(self, source)
   }
 }
@@ -183,11 +183,11 @@ impl InternedDisplay for AnyMatcher {
 /// vectorial placeholders and handles the scalars on leaves.
 pub struct VectreeMatcher(AnyMatcher);
 impl Matcher for VectreeMatcher {
-  fn new(pattern: Rc<Vec<Expr>>) -> Self {
+  fn new(pattern: Rc<Vec<RuleExpr>>) -> Self {
     Self(AnyMatcher::new(pattern))
   }
 
-  fn apply<'a>(&self, source: &'a [Expr]) -> Option<State<'a>> {
+  fn apply<'a>(&self, source: &'a [RuleExpr]) -> Option<State<'a>> {
     self.0.apply(source)
   }
 }
diff --git a/src/rule/matcher_vectree/vec_match.rs b/src/rule/matcher_vectree/vec_match.rs
index 0b155f9..e8b5ced 100644
--- a/src/rule/matcher_vectree/vec_match.rs
+++ b/src/rule/matcher_vectree/vec_match.rs
@@ -4,13 +4,13 @@ use itertools::Itertools;
 
 use super::scal_match::scalv_match;
 use super::shared::VecMatcher;
-use crate::ast::Expr;
+use crate::rule::matcher::RuleExpr;
 use crate::rule::state::{State, StateEntry};
 use crate::utils::unwrap_or;
 
 pub fn vec_match<'a>(
   matcher: &VecMatcher,
-  seq: &'a [Expr],
+  seq: &'a [RuleExpr],
 ) -> Option<State<'a>> {
   match matcher {
     VecMatcher::Placeh { key, nonzero } => {
diff --git a/src/rule/prepare_rule.rs b/src/rule/prepare_rule.rs
index e466f57..47b8f70 100644
--- a/src/rule/prepare_rule.rs
+++ b/src/rule/prepare_rule.rs
@@ -1,24 +1,24 @@
-use std::rc::Rc;
-
 use hashbrown::HashMap;
 use itertools::Itertools;
 
+use super::matcher::RuleExpr;
 use super::vec_attrs::vec_attrs;
 use super::RuleError;
 use crate::ast::{Clause, Expr, PHClass, Placeholder, Rule};
 use crate::interner::{Interner, Tok};
 use crate::representations::location::Location;
+use crate::Sym;
 
 /// Ensure that the rule's source begins and ends with a vectorial without
 /// changing its meaning
-fn pad(mut rule: Rule, i: &Interner) -> Rule {
+fn pad(mut rule: Rule<Sym>, i: &Interner) -> Rule<Sym> {
   let class: PHClass = PHClass::Vec { nonzero: false, prio: 0 };
-  let empty: &[Expr] = &[];
-  let prefix: &[Expr] = &[Expr {
+  let empty: &[Expr<Sym>] = &[];
+  let prefix: &[Expr<Sym>] = &[Expr {
     location: Location::Unknown,
     value: Clause::Placeh(Placeholder { name: i.i("::prefix"), class }),
   }];
-  let suffix: &[Expr] = &[Expr {
+  let suffix: &[Expr<Sym>] = &[Expr {
     location: Location::Unknown,
     value: Clause::Placeh(Placeholder { name: i.i("::suffix"), class }),
   }];
@@ -28,22 +28,14 @@ fn pad(mut rule: Rule, i: &Interner) -> Rule {
   let suffix_explicit = vec_attrs(rule_tail).is_some();
   let prefix_v = if prefix_explicit { empty } else { prefix };
   let suffix_v = if suffix_explicit { empty } else { suffix };
-  rule.pattern = Rc::new(
-    prefix_v
-      .iter()
-      .chain(rule.pattern.iter())
-      .chain(suffix_v.iter())
-      .cloned()
-      .collect(),
-  );
-  rule.template = Rc::new(
-    prefix_v
-      .iter()
-      .chain(rule.template.iter())
-      .chain(suffix_v.iter())
-      .cloned()
-      .collect(),
-  );
+  rule.pattern = (prefix_v.iter().cloned())
+    .chain(rule.pattern.into_iter())
+    .chain(suffix_v.iter().cloned())
+    .collect();
+  rule.template = (prefix_v.iter().cloned())
+    .chain(rule.template.into_iter())
+    .chain(suffix_v.iter().cloned())
+    .collect();
   rule
 }
 
@@ -62,7 +54,7 @@ impl From<PHClass> for PHType {
 }
 
 fn check_rec_expr(
-  expr: &Expr,
+  expr: &RuleExpr,
   types: &mut HashMap<Tok<String>, PHType>,
   in_template: bool,
 ) -> Result<(), RuleError> {
@@ -95,7 +87,7 @@ fn check_rec_expr(
 }
 
 fn check_rec_exprv(
-  exprv: &[Expr],
+  exprv: &[RuleExpr],
   types: &mut HashMap<Tok<String>, PHType>,
   in_template: bool,
 ) -> Result<(), RuleError> {
@@ -115,7 +107,10 @@ fn check_rec_exprv(
   }
 }
 
-pub fn prepare_rule(rule: Rule, i: &Interner) -> Result<Rule, RuleError> {
+pub fn prepare_rule(
+  rule: Rule<Sym>,
+  i: &Interner,
+) -> Result<Rule<Sym>, RuleError> {
   // Dimension check
   let mut types = HashMap::new();
   check_rec_exprv(&rule.pattern, &mut types, false)?;
diff --git a/src/rule/repository.rs b/src/rule/repository.rs
index 5a3aed5..c2f46df 100644
--- a/src/rule/repository.rs
+++ b/src/rule/repository.rs
@@ -5,19 +5,20 @@ use std::rc::Rc;
 use hashbrown::HashSet;
 use ordered_float::NotNan;
 
-use super::matcher::Matcher;
+use super::matcher::{Matcher, RuleExpr};
 use super::prepare_rule::prepare_rule;
 use super::state::apply_exprv;
 use super::{update_first_seq, RuleError, VectreeMatcher};
-use crate::ast::{Expr, Rule};
-use crate::interner::{InternedDisplay, Interner, Sym};
+use crate::ast::Rule;
+use crate::interner::{InternedDisplay, Interner};
 use crate::utils::Substack;
+use crate::Sym;
 
 #[derive(Debug)]
 pub struct CachedRule<M: Matcher> {
   matcher: M,
-  pattern: Rc<Vec<Expr>>,
-  template: Rc<Vec<Expr>>,
+  pattern: Vec<RuleExpr>,
+  template: Vec<RuleExpr>,
 }
 
 impl<M: InternedDisplay + Matcher> InternedDisplay for CachedRule<M> {
@@ -48,9 +49,9 @@ pub struct Repository<M: Matcher> {
 impl<M: Matcher> Repository<M> {
   /// Build a new repository to hold the given set of rules
   pub fn new(
-    mut rules: Vec<Rule>,
+    mut rules: Vec<Rule<Sym>>,
     i: &Interner,
-  ) -> Result<Self, (Rule, RuleError)> {
+  ) -> Result<Self, (Rule<Sym>, RuleError)> {
     rules.sort_by_key(|r| -r.prio);
     let cache = rules
       .into_iter()
@@ -60,10 +61,10 @@ impl<M: Matcher> Repository<M> {
         let mut glossary = HashSet::new();
         for e in rule.pattern.iter() {
           e.visit_names(Substack::Bottom, &mut |op| {
-            glossary.insert(op);
+            glossary.insert(*op);
           })
         }
-        let matcher = M::new(rule.pattern.clone());
+        let matcher = M::new(Rc::new(rule.pattern.clone()));
         let prep = CachedRule {
           matcher,
           pattern: rule.pattern,
@@ -76,10 +77,10 @@ impl<M: Matcher> Repository<M> {
   }
 
   /// Attempt to run each rule in priority order once
-  pub fn step(&self, code: &Expr) -> Option<Expr> {
+  pub fn step(&self, code: &RuleExpr) -> Option<RuleExpr> {
     let mut glossary = HashSet::new();
     code.visit_names(Substack::Bottom, &mut |op| {
-      glossary.insert(op);
+      glossary.insert(*op);
     });
     for (rule, deps, _) in self.cache.iter() {
       if !deps.is_subset(&glossary) {
@@ -100,7 +101,7 @@ impl<M: Matcher> Repository<M> {
   /// Keep running the matching rule with the highest priority until no
   /// rules match. WARNING: this function might not terminate
   #[allow(unused)]
-  pub fn pass(&self, code: &Expr) -> Option<Expr> {
+  pub fn pass(&self, code: &RuleExpr) -> Option<RuleExpr> {
     if let Some(mut processed) = self.step(code) {
       while let Some(out) = self.step(&processed) {
         processed = out
@@ -114,7 +115,11 @@ impl<M: Matcher> Repository<M> {
   /// Attempt to run each rule in priority order `limit` times. Returns
   /// the final tree and the number of iterations left to the limit.
   #[allow(unused)]
-  pub fn long_step(&self, code: &Expr, mut limit: usize) -> (Expr, usize) {
+  pub fn long_step(
+    &self,
+    code: &RuleExpr,
+    mut limit: usize,
+  ) -> (RuleExpr, usize) {
     if limit == 0 {
       return (code.clone(), 0);
     }
diff --git a/src/rule/state.rs b/src/rule/state.rs
index f04e413..ca85211 100644
--- a/src/rule/state.rs
+++ b/src/rule/state.rs
@@ -3,18 +3,19 @@ use std::rc::Rc;
 use hashbrown::HashMap;
 use itertools::Itertools;
 
+use super::matcher::RuleExpr;
 use crate::ast::{Clause, Expr, PHClass, Placeholder};
 use crate::interner::Tok;
 use crate::utils::unwrap_or;
 
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum StateEntry<'a> {
-  Vec(&'a [Expr]),
-  Scalar(&'a Expr),
+  Vec(&'a [RuleExpr]),
+  Scalar(&'a RuleExpr),
 }
 pub type State<'a> = HashMap<Tok<String>, StateEntry<'a>>;
 
-pub fn apply_exprv(template: &[Expr], state: &State) -> Vec<Expr> {
+pub fn apply_exprv(template: &[RuleExpr], state: &State) -> Vec<RuleExpr> {
   template
     .iter()
     .map(|e| apply_expr(e, state))
@@ -22,7 +23,7 @@ pub fn apply_exprv(template: &[Expr], state: &State) -> Vec<Expr> {
     .collect()
 }
 
-pub fn apply_expr(template: &Expr, state: &State) -> Vec<Expr> {
+pub fn apply_expr(template: &RuleExpr, state: &State) -> Vec<RuleExpr> {
   let Expr { location, value } = template;
   match value {
     Clause::P(_) | Clause::Name(_) => vec![template.clone()],
diff --git a/src/rule/update_first_seq.rs b/src/rule/update_first_seq.rs
index 5044440..fd8625a 100644
--- a/src/rule/update_first_seq.rs
+++ b/src/rule/update_first_seq.rs
@@ -1,15 +1,17 @@
 use std::rc::Rc;
 
+use super::matcher::RuleExpr;
 use crate::ast::{Clause, Expr};
 use crate::utils::replace_first;
+use crate::Sym;
 
 /// Traverse the tree, calling pred on every sibling list until it returns
 /// some vec then replace the sibling list with that vec and return true
 /// return false if pred never returned some
-pub fn exprv<F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>>(
-  input: Rc<Vec<Expr>>,
+pub fn exprv<F: FnMut(Rc<Vec<RuleExpr>>) -> Option<Rc<Vec<RuleExpr>>>>(
+  input: Rc<Vec<RuleExpr>>,
   pred: &mut F,
-) -> Option<Rc<Vec<Expr>>> {
+) -> Option<Rc<Vec<RuleExpr>>> {
   if let Some(v) = pred(input.clone()) {
     return Some(v);
   }
@@ -17,18 +19,18 @@ pub fn exprv<F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>>(
     .map(|i| Rc::new(i.collect()))
 }
 
-pub fn expr<F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>>(
-  input: &Expr,
+pub fn expr<F: FnMut(Rc<Vec<RuleExpr>>) -> Option<Rc<Vec<RuleExpr>>>>(
+  input: &RuleExpr,
   pred: &mut F,
-) -> Option<Expr> {
+) -> Option<RuleExpr> {
   clause(&input.value, pred)
     .map(|value| Expr { value, location: input.location.clone() })
 }
 
-pub fn clause<F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>>(
-  c: &Clause,
+pub fn clause<F: FnMut(Rc<Vec<RuleExpr>>) -> Option<Rc<Vec<RuleExpr>>>>(
+  c: &Clause<Sym>,
   pred: &mut F,
-) -> Option<Clause> {
+) -> Option<Clause<Sym>> {
   match c {
     Clause::P(_) | Clause::Placeh { .. } | Clause::Name { .. } => None,
     Clause::Lambda(arg, body) =>
diff --git a/src/rule/vec_attrs.rs b/src/rule/vec_attrs.rs
index 3f7582b..aee13ba 100644
--- a/src/rule/vec_attrs.rs
+++ b/src/rule/vec_attrs.rs
@@ -1,9 +1,10 @@
-use crate::ast::{Clause, Expr, PHClass, Placeholder};
+use super::matcher::RuleExpr;
+use crate::ast::{Clause, PHClass, Placeholder};
 use crate::interner::Tok;
 
 /// Returns the name, priority and nonzero of the expression if it is
 /// a vectorial placeholder
-pub fn vec_attrs(expr: &Expr) -> Option<(Tok<String>, u64, bool)> {
+pub fn vec_attrs(expr: &RuleExpr) -> Option<(Tok<String>, u64, bool)> {
   if let Clause::Placeh(Placeholder {
     class: PHClass::Vec { prio, nonzero },
     name,
diff --git a/src/stl/mk_stl.rs b/src/stl/mk_stl.rs
index 7eb630f..796b0ec 100644
--- a/src/stl/mk_stl.rs
+++ b/src/stl/mk_stl.rs
@@ -6,9 +6,10 @@ use super::conv::conv;
 use super::io::io;
 use super::num::num;
 use super::str::str;
-use crate::interner::{Interner, Sym};
+use crate::interner::Interner;
 use crate::pipeline::file_loader::mk_embed_cache;
 use crate::pipeline::{from_const_tree, parse_layer, ProjectTree};
+use crate::representations::VName;
 use crate::sourcefile::{FileEntry, Import};
 
 /// Feature flags for the STL.
@@ -29,29 +30,28 @@ struct StlEmbed;
 
 /// Build the standard library used by the interpreter by combining the other
 /// libraries
-pub fn mk_stl(i: &Interner, options: StlOptions) -> ProjectTree {
+pub fn mk_stl(i: &Interner, options: StlOptions) -> ProjectTree<VName> {
   let const_tree = from_const_tree(
     HashMap::from([(
       i.i("std"),
       io(i, options.impure) + conv(i) + bool(i) + str(i) + num(i),
     )]),
     &[i.i("std")],
-    i,
   );
   let ld_cache = mk_embed_cache::<StlEmbed>(".orc", i);
+  let targets = StlEmbed::iter()
+    .map(|path| {
+      path
+        .strip_suffix(".orc")
+        .expect("the embed is filtered for suffix")
+        .split('/')
+        .map(|segment| i.i(segment))
+        .collect::<Vec<_>>()
+    })
+    .collect::<Vec<_>>();
   parse_layer(
-    &StlEmbed::iter()
-      .map(|path| -> Sym {
-        let segtoks = path
-          .strip_suffix(".orc")
-          .expect("the embed is filtered for suffix")
-          .split('/')
-          .map(|segment| i.i(segment))
-          .collect::<Vec<_>>();
-        i.i(&segtoks[..])
-      })
-      .collect::<Vec<_>>()[..],
-    &|p| ld_cache.find(&p),
+    targets.iter().map(|v| &v[..]),
+    &|p| ld_cache.find(p),
     &const_tree,
     &[],
     i,
diff --git a/src/utils/cache.rs b/src/utils/cache.rs
index 0afcd7e..2695eaa 100644
--- a/src/utils/cache.rs
+++ b/src/utils/cache.rs
@@ -1,3 +1,4 @@
+use std::borrow::Borrow;
 use std::cell::RefCell;
 use std::hash::Hash;
 
@@ -23,19 +24,23 @@ impl<'a, I: Eq + Hash + Clone, O: Clone> Cache<'a, I, O> {
   }
 
   /// Produce and cache a result by cloning I if necessary
-  pub fn find(&self, i: &I) -> O {
+  pub fn find<Q: ?Sized>(&self, q: &Q) -> O
+  where
+    Q: Eq + Hash + ToOwned<Owned = I>,
+    I: Borrow<Q>,
+  {
     let closure = &self.closure;
-    if let Some(v) = self.store.borrow().get(i) {
+    if let Some(v) = self.store.borrow().get(q) {
       return v.clone();
     }
     // In the moment of invocation the refcell is on immutable
     // this is important for recursive calculations
-    let result = closure(i.clone(), self);
+    let result = closure(q.to_owned(), self);
     let mut store = self.store.borrow_mut();
     store
       .raw_entry_mut()
-      .from_key(i)
-      .or_insert_with(|| (i.clone(), result))
+      .from_key(q)
+      .or_insert_with(|| (q.to_owned(), result))
       .1
       .clone()
   }
diff --git a/src/utils/mod.rs b/src/utils/mod.rs
index 1c01525..bae24df 100644
--- a/src/utils/mod.rs
+++ b/src/utils/mod.rs
@@ -1,6 +1,7 @@
 mod cache;
 mod print_nname;
 mod pushed;
+mod rc_to_owned;
 mod replace_first;
 mod side;
 mod split_max_prefix;
@@ -11,6 +12,7 @@ mod unwrap_or;
 pub use cache::Cache;
 pub use print_nname::sym2string;
 pub use pushed::pushed;
+pub use rc_to_owned::{map_rc, rc_to_owned};
 pub use replace_first::replace_first;
 pub use side::Side;
 pub use split_max_prefix::split_max_prefix;
diff --git a/src/utils/print_nname.rs b/src/utils/print_nname.rs
index 27c2203..d3301ca 100644
--- a/src/utils/print_nname.rs
+++ b/src/utils/print_nname.rs
@@ -1,6 +1,7 @@
 use itertools::Itertools;
 
-use crate::interner::{Interner, Sym};
+use crate::interner::Interner;
+use crate::Sym;
 
 /// Print symbols to :: delimited strings
 pub fn sym2string(t: Sym, i: &Interner) -> String {
diff --git a/src/utils/rc_to_owned.rs b/src/utils/rc_to_owned.rs
new file mode 100644
index 0000000..db031cd
--- /dev/null
+++ b/src/utils/rc_to_owned.rs
@@ -0,0 +1,9 @@
+use std::rc::Rc;
+
+pub fn rc_to_owned<T: Clone>(rc: Rc<T>) -> T {
+  Rc::try_unwrap(rc).unwrap_or_else(|rc| rc.as_ref().clone())
+}
+
+pub fn map_rc<T: Clone, U>(rc: Rc<T>, pred: impl FnOnce(T) -> U) -> Rc<U> {
+  Rc::new(pred(rc_to_owned(rc)))
+}
diff --git a/src/utils/unwrap_or.rs b/src/utils/unwrap_or.rs
index 62b0c06..944835f 100644
--- a/src/utils/unwrap_or.rs
+++ b/src/utils/unwrap_or.rs
@@ -1,6 +1,17 @@
 /// A macro version of [Option::unwrap_or_else] which supports flow
 /// control statements such as `return` and `break` in the "else" branch.
+///
+/// ```ignore
+/// crate::unwrap_or!(Some(1); return)
+/// ```
+///
 /// It also supports unwrapping concrete variants of other enums
+///
+/// ```ignore
+/// use crate::representations::Literal;
+///
+/// crate::unwrap_or!(Literal::Usize(2) => Literal::Number; return)
+/// ```
 macro_rules! unwrap_or {
   ($m:expr; $fail:expr) => {{
     if let Some(res) = ($m) { res } else { $fail }