diff --git a/Cargo.toml b/Cargo.toml
index 41c62ef..bf58b25 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22,3 +22,8 @@ lalrpop = "0.19.6"
 [dev-dependencies]
 assert_cmd = "2.0.2"
 insta = { version = "1.9.0", features = ["glob"] }
+
+[profile.dev]
+# https://github.com/rust-lang/rust/issues/92163
+# https://github.com/rust-lang/rust/issues/92315
+incremental=false
\ No newline at end of file
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..1effd75
--- /dev/null
+++ b/README.md
@@ -0,0 +1,3 @@
+## Credits
+
+Many of the tests are adapted from [craftinginterpriters](https://github.com/munificent/craftinginterpreters/tree/master/test).
\ No newline at end of file
diff --git a/src/ast.rs b/src/ast.rs
index cdd9503..6d99b4b 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -1,20 +1,25 @@
 use std::rc::Rc;
 
-#[derive(Debug, debug2::Debug, PartialEq)]
+#[derive(Debug /*/*, debug2::Debug*/*/, PartialEq)]
 
 crate enum Tree {
     Leaf(Literal),
     Define(String, Box<Tree>),
+    Set(String, Box<Tree>),
     If(Box<[Tree; 3]>),
-    Lambda(Lambda),
+    // Its easier to box the lambdas in the parser than the vm, as
+    // here we see all of them exactly once
+    Func(Rc<Func>),
     Branch(Vec<Tree>),
 }
 
-#[derive(Debug, debug2::Debug, PartialEq, Clone)]
+#[derive(Debug /*/*, debug2::Debug*/*/, PartialEq)]
+crate struct Func {
+    crate args: Vec<String>,
+    crate body: Vec<Tree>,
+}
 
-crate struct Lambda(crate Rc<[String]>, crate Rc<[Tree]>);
-
-#[derive(Debug, debug2::Debug, PartialEq)]
+#[derive(Debug /*/*, debug2::Debug*/*/, PartialEq)]
 
 crate enum Literal {
     Sym(String),
diff --git a/src/eval.rs b/src/eval.rs
index b9dbd8d..fb4d850 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -1,58 +1,82 @@
 use std::assert_matches::assert_matches;
+use std::cell::RefCell;
 use std::collections::HashMap;
+use std::rc::Rc;
 
 use crate::value::Value;
 use crate::{ast, prims};
 
-pub(crate) fn eval(t: &ast::Tree, env: &mut Env) -> Result<Value, RTError> {
+#[derive(/*debug2::Debug,*/ Debug, Clone)]
+crate struct Lambda {
+    crate func: Rc<ast::Func>,
+    crate captures: Rc<RefCell<Env>>,
+}
+
+pub(crate) fn eval(t: &ast::Tree, env: Rc<RefCell<Env>>) -> Result<Value, RTError> {
     Ok(match t {
         ast::Tree::Leaf(l) => match l {
-            ast::Literal::Sym(s) => match env.lookup(s) {
+            ast::Literal::Sym(s) => match env.borrow().lookup(s) {
                 Some(v) => v,
                 None => return err(format!("Undefined variable `{}`", s)),
             },
             ast::Literal::Num(v) => Value::Num(*v),
             ast::Literal::Bool(b) => Value::Bool(*b),
         },
-        ast::Tree::Lambda(l) => Value::Lambda(l.clone()),
+        ast::Tree::Func(l) => Value::Lambda(Lambda {
+            func: Rc::clone(l),
+            captures: Rc::clone(&env),
+        }),
         ast::Tree::Branch(args) => {
-            let Some(fun) = args.get(0) else { return err("No argument given".to_owned()) };
-            let fun = eval(fun, env)?;
-            let fun = fun.as_func()?;
+            let Some(fun) = args.get(0) else { return err("No func given".to_owned()) };
+
+            let fun = eval(fun, Rc::clone(&env))?.as_func()?;
+
             let args = args
                 .iter()
                 .skip(1)
-                .map(|a| eval(a, env))
+                .map(|a| eval(a, Rc::clone(&env)))
                 .collect::<Result<Vec<_>, _>>()?;
-            // return fun(&args);
+
             match fun {
                 Callable::Func(f) => f(&args)?,
                 Callable::Lambda(l) => {
-                    if l.0.len() == args.len() {
-                        let mut env = env.child();
-                        for (x, y) in l.0.iter().zip(args) {
+                    if l.func.args.len() == args.len() {
+                        // let mut env = env.child();
+                        let mut env = Env::child(Rc::clone(&l.captures));
+
+                        for (x, y) in l.func.args.iter().zip(args) {
                             env.define(x.clone(), y)
                         }
+                        let env = Rc::new(RefCell::new(env));
 
-                        let [main @ .., tail] = &l.1[..] else { unreachable!("Body has 1+ element by parser") };
+                        let [main @ .., tail] = &l.func.body[..] else { unreachable!("Body has 1+ element by parser") };
                         for i in main {
-                            eval(i, &mut env)?;
+                            eval(i, Rc::clone(&env))?;
                         }
 
-                        eval(tail, &mut env)?
+                        eval(tail, env)?
                     } else {
-                        return err(format!("Need {} args, got {}", l.0.len(), args.len()));
+                        return err(format!(
+                            "Need {} args, got {}",
+                            l.func.args.len(),
+                            args.len()
+                        ));
                     }
                 }
             }
         }
         ast::Tree::Define(name, to) => {
-            let val = eval(to, env)?;
-            env.define(name.to_owned(), val);
+            let val = eval(to, Rc::clone(&env))?;
+            env.borrow_mut().define(name.to_owned(), val);
+            Value::Trap
+        }
+        ast::Tree::Set(name, to) => {
+            let val = eval(to, Rc::clone(&env))?;
+            env.borrow_mut().set(name, val)?;
             Value::Trap
         }
         ast::Tree::If(box [cond, tcase, fcase]) => {
-            let b = eval(cond, env)?.as_bool()?;
+            let b = eval(cond, Rc::clone(&env))?.as_bool()?;
             let body = if b { tcase } else { fcase };
             eval(body, env)?
         }
@@ -66,40 +90,72 @@ pub(crate) fn err<T>(s: String) -> Result<T, RTError> {
     Err(RTError(s))
 }
 
-pub(crate) enum Callable<'a> {
-    Func(prims::Func),
-    Lambda(&'a ast::Lambda),
+pub(crate) enum Callable {
+    Func(prims::NativeFunc),
+    Lambda(Lambda),
 }
 
-pub(crate) struct Env<'a> {
-    pub(crate) vars: HashMap<String, Value>,
-    pub(crate) enclosing: Option<&'a Env<'a>>,
+#[derive(Clone /*, debug2::Debug*/)]
+pub(crate) struct Env {
+    vars: HashMap<String, Value>,
+    enclosing: Option<Rc<RefCell<Env>>>,
 }
 
-impl<'a> Env<'a> {
-    pub(crate) fn child(&'a self) -> Env<'a> {
+impl std::fmt::Debug for Env {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        struct Vars<'a>(&'a HashMap<String, Value>);
+
+        impl std::fmt::Debug for Vars<'_> {
+            fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+                f.debug_set().entries(self.0.keys()).finish()
+            }
+        }
+
+        f.debug_struct("Env")
+            .field("vars", &Vars(&self.vars))
+            .field("enclosing", &self.enclosing)
+            .finish()
+    }
+}
+
+impl Env {
+    pub(crate) fn child(this: Rc<RefCell<Self>>) -> Env {
         Env {
             vars: HashMap::new(),
-            enclosing: Some(self),
+            enclosing: Some(this),
         }
     }
 
     pub(crate) fn lookup(&self, s: &str) -> Option<Value> {
         if let Some(v) = self.vars.get(s) {
             Some(v.clone())
-        } else if let Some(parent) = self.enclosing {
-            parent.lookup(s)
+        } else if let Some(parent) = &self.enclosing {
+            parent.borrow().lookup(s)
         } else {
             None
         }
     }
 
     pub(crate) fn define(&mut self, name: String, val: Value) {
+        assert_ne!(val, Value::Trap); // TODO: Better error
+
+        // TODO: Error on previous def
         self.vars.insert(name, val);
     }
+
+    crate fn set(&mut self, name: &str, val: Value) -> Result<(), RTError> {
+        if let Some(loc) = self.vars.get_mut(name) {
+            *loc = val;
+            Ok(())
+        } else if let Some(parent) = &self.enclosing {
+            parent.borrow_mut().set(name, val)
+        } else {
+            err(format!("Tried to `set!` un `define`d var `{}`", name))
+        }
+    }
 }
 
-pub(crate) fn default_env() -> Env<'static> {
+pub(crate) fn default_env() -> Env {
     let mut vars = HashMap::new();
 
     for (name, fun) in prims::prims() {
diff --git a/src/grammar.lalrpop b/src/grammar.lalrpop
index 681053d..b85479b 100644
--- a/src/grammar.lalrpop
+++ b/src/grammar.lalrpop
@@ -17,9 +17,11 @@ Trees = Tree+;
 pub(crate) Tree: Tree = {
     "(" <Tree+> ")" => Tree::Branch(<>),
     "(" "define" <Sym> <BTree> ")" => Tree::Define(<>),
-    "(" "define" "(" <name:Sym> <args:RcSlice<Sym>> ")" <body:RcSlice<Tree>> ")" => Tree::Define(name, Box::new(Tree::Lambda(Lambda(args, body)))),
+    "(" "define" "(" <name:Sym> <args:Sym*> ")" <body:Trees> ")" 
+        => Tree::Define(name, Box::new(Tree::Func(Rc::new(Func{args, body})))),
     "(" "if" <Tree> <Tree> <Tree> ")" => Tree::If(Box::new([<>])),
-    "(" "lambda (" <RcSlice<Sym>> ")" <RcSlice<Tree>> ")" => Tree::Lambda(Lambda(<>)),
+    "(" "lambda (" <args:Sym*> ")" <body:Trees> ")" => Tree::Func(Rc::new(Func{<>})),
+    "(" "set!" <Sym> <BTree> ")" => Tree::Set(<>),
     Literal => Tree::Leaf(<>),
 }
 
diff --git a/src/grammar.rs b/src/grammar.rs
index 5175c41..8b7d0b8 100644
--- a/src/grammar.rs
+++ b/src/grammar.rs
@@ -1,13 +1,13 @@
 // auto-generated: "lalrpop 0.19.6"
-// sha3: c1daa5330c6265bff388c19ed1642efbf9924c741dbad19b8016bd2a5a646
+// sha3: 5cdf62b36e7f305a16087e7575bb60a55df0da8fdd57413f4ded28c458e7da
 use crate::ast::*;
 use std::rc::Rc;
 #[allow(unused_extern_crates)]
 extern crate lalrpop_util as __lalrpop_util;
 #[allow(unused_imports)]
 use self::__lalrpop_util::state_machine as __state_machine;
-extern crate alloc;
 extern crate core;
+extern crate alloc;
 
 #[cfg_attr(rustfmt, rustfmt_skip)]
 mod __parse__File {
@@ -33,114 +33,128 @@ mod __parse__File {
         Variant5(core::option::Option<()>),
         Variant6(Literal),
         Variant7(f64),
-        Variant8(Rc<[String]>),
-        Variant9(Rc<[Tree]>),
-        Variant10(String),
-        Variant11(alloc::vec::Vec<String>),
-        Variant12(Tree),
+        Variant8(String),
+        Variant9(alloc::vec::Vec<String>),
+        Variant10(Tree),
     }
     const __ACTION: &[i8] = &[
         // State 0
-        26, 4, 27, 5, 0, 0, 0, 0, 0, 0, 28, 29,
+        30, 4, 31, 5, 0, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 1
-        26, 0, 27, 5, 0, 0, 0, 0, 0, 0, 28, 29,
+        30, 0, 31, 5, 0, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 2
-        26, 0, 27, 5, 0, 0, 0, 0, 0, 0, 28, 29,
+        30, 0, 31, 5, -32, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 3
-        0, 0, 0, 0, 0, 0, 0, 0, 33, 34, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 37, 38, 0, 0, 0,
         // State 4
-        26, 0, 27, 5, 0, 7, 8, 9, 0, 0, 28, 29,
+        30, 0, 31, 5, 0, 7, 8, 9, 0, 0, 10, 32, 33,
         // State 5
-        26, 0, 27, 5, 35, 0, 0, 0, 0, 0, 28, 29,
+        30, 0, 31, 5, 39, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 6
-        0, 0, 0, 11, 0, 0, 0, 0, 0, 0, 0, 29,
+        0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0, 0, 33,
         // State 7
-        26, 0, 27, 5, 0, 0, 0, 0, 0, 0, 28, 29,
+        30, 0, 31, 5, 0, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 8
-        0, 0, 0, 0, -16, 0, 0, 0, 0, 0, 0, 29,
+        0, 0, 0, 0, 15, 0, 0, 0, 0, 0, 0, 0, 33,
         // State 9
-        26, 0, 27, 5, 0, 0, 0, 0, 0, 0, 28, 29,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 33,
         // State 10
-        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 29,
+        30, 0, 31, 5, 0, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 11
-        26, 0, 27, 5, 0, 0, 0, 0, 0, 0, 28, 29,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 33,
         // State 12
-        0, 0, 0, 0, -17, 0, 0, 0, 0, 0, 0, 29,
+        30, 0, 31, 5, 0, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 13
-        0, 0, 0, 0, -16, 0, 0, 0, 0, 0, 0, 29,
+        0, 0, 0, 0, 19, 0, 0, 0, 0, 0, 0, 0, 33,
         // State 14
-        26, 0, 27, 5, 0, 0, 0, 0, 0, 0, 28, 29,
+        30, 0, 31, 5, 0, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 15
-        26, 0, 27, 5, -18, 0, 0, 0, 0, 0, 28, 29,
+        30, 0, 31, 5, 0, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 16
-        26, 0, 27, 5, -19, 0, 0, 0, 0, 0, 28, 29,
+        0, 0, 0, 0, 21, 0, 0, 0, 0, 0, 0, 0, 33,
         // State 17
-        26, 0, 27, 5, -18, 0, 0, 0, 0, 0, 28, 29,
+        30, 0, 31, 5, 0, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 18
-        -14, 0, -14, -14, -14, 0, 0, 0, 0, 0, -14, -14,
+        30, 0, 31, 5, 0, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 19
-        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 22, 0, 0, 0, 0, 0, 0, 0, 33,
         // State 20
-        -30, 0, -30, -30, -30, 0, 0, 0, 0, 0, -30, -30,
+        30, 0, 31, 5, 0, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 21
-        -13, 0, -13, -13, -13, 0, 0, 0, 0, 0, -13, -13,
+        30, 0, 31, 5, 0, 0, 0, 0, 0, 0, 0, 32, 33,
         // State 22
-        -12, 0, -12, -12, -12, 0, 0, 0, 0, 0, -12, -12,
+        -14, 0, -14, -14, -14, 0, 0, 0, 0, 0, 0, -14, -14,
         // State 23
-        -33, 0, -33, -33, -33, 0, 0, 0, 0, 0, -33, -33,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 24
-        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        -29, 0, -29, -29, -29, 0, 0, 0, 0, 0, 0, -29, -29,
         // State 25
-        -3, 0, -3, -3, -3, 0, 0, 0, 0, 0, -3, -3,
+        -13, 0, -13, -13, -13, 0, 0, 0, 0, 0, 0, -13, -13,
         // State 26
-        -2, 0, -2, -2, -2, 0, 0, 0, 0, 0, -2, -2,
+        -12, 0, -12, -12, -12, 0, 0, 0, 0, 0, 0, -12, -12,
         // State 27
-        -15, 0, -15, -15, -15, 0, 0, 0, 0, 0, -15, -15,
+        -30, 0, -30, -30, -30, 0, 0, 0, 0, 0, 0, -30, -30,
         // State 28
-        -20, 0, -20, -20, -20, 0, 0, 0, 0, 0, -20, -20,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 29
-        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        -3, 0, -3, -3, -3, 0, 0, 0, 0, 0, 0, -3, -3,
         // State 30
-        -34, 0, -34, -34, -34, 0, 0, 0, 0, 0, -34, -34,
+        -2, 0, -2, -2, -2, 0, 0, 0, 0, 0, 0, -2, -2,
         // State 31
-        -7, 0, -7, -7, 0, 0, 0, 0, 0, 0, -7, -7,
+        -15, 0, -15, -15, -15, 0, 0, 0, 0, 0, 0, -15, -15,
         // State 32
-        -11, 0, -11, -11, 0, 0, 0, 0, 0, 0, -11, -11,
+        -16, 0, -16, -16, -16, 0, 0, 0, 0, 0, 0, -16, -16,
         // State 33
-        -10, 0, -10, -10, 0, 0, 0, 0, 0, 0, -10, -10,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 34
-        -25, 0, -25, -25, -25, 0, 0, 0, 0, 0, -25, -25,
+        -31, 0, -31, -31, -31, 0, 0, 0, 0, 0, 0, -31, -31,
         // State 35
-        0, 0, 0, 0, 16, 0, 0, 0, 0, 0, 0, 0,
+        -7, 0, -7, -7, 0, 0, 0, 0, 0, 0, 0, -7, -7,
         // State 36
-        0, 0, 0, 0, -23, 0, 0, 0, 0, 0, 0, -23,
+        -11, 0, -11, -11, 0, 0, 0, 0, 0, 0, 0, -11, -11,
         // State 37
-        0, 0, 0, 0, 42, 0, 0, 0, 0, 0, 0, 0,
+        -10, 0, -10, -10, 0, 0, 0, 0, 0, 0, 0, -10, -10,
         // State 38
-        0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0,
+        -21, 0, -21, -21, -21, 0, 0, 0, 0, 0, 0, -21, -21,
         // State 39
-        0, 0, 0, 0, -4, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, -19, 0, 0, 0, 0, 0, 0, 0, -19,
         // State 40
-        0, 0, 0, 0, -24, 0, 0, 0, 0, 0, 0, -24,
+        0, 0, 0, 0, 47, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 41
-        -26, 0, -26, -26, -26, 0, 0, 0, 0, 0, -26, -26,
+        0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 42
-        0, 0, 0, 0, 18, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, -4, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 43
-        0, 0, 0, 0, 46, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, -20, 0, 0, 0, 0, 0, 0, 0, -20,
         // State 44
-        0, 0, 0, 0, 47, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 50, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 45
-        -28, 0, -28, -28, -28, 0, 0, 0, 0, 0, -28, -28,
+        0, 0, 0, 0, 51, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 46
-        -29, 0, -29, -29, -29, 0, 0, 0, 0, 0, -29, -29,
+        -22, 0, -22, -22, -22, 0, 0, 0, 0, 0, 0, -22, -22,
         // State 47
-        0, 0, 0, 0, 49, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 53, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 48
-        -27, 0, -27, -27, -27, 0, 0, 0, 0, 0, -27, -27,
+        0, 0, 0, 0, 54, 0, 0, 0, 0, 0, 0, 0, 0,
+        // State 49
+        -26, 0, -26, -26, -26, 0, 0, 0, 0, 0, 0, -26, -26,
+        // State 50
+        -28, 0, -28, -28, -28, 0, 0, 0, 0, 0, 0, -28, -28,
+        // State 51
+        0, 0, 0, 0, 56, 0, 0, 0, 0, 0, 0, 0, 0,
+        // State 52
+        -25, 0, -25, -25, -25, 0, 0, 0, 0, 0, 0, -25, -25,
+        // State 53
+        -27, 0, -27, -27, -27, 0, 0, 0, 0, 0, 0, -27, -27,
+        // State 54
+        0, 0, 0, 0, 57, 0, 0, 0, 0, 0, 0, 0, 0,
+        // State 55
+        -23, 0, -23, -23, -23, 0, 0, 0, 0, 0, 0, -23, -23,
+        // State 56
+        -24, 0, -24, -24, -24, 0, 0, 0, 0, 0, 0, -24, -24,
     ];
     fn __action(state: i8, integer: usize) -> i8 {
-        __ACTION[(state as usize) * 12 + integer]
+        __ACTION[(state as usize) * 13 + integer]
     }
     const __EOF_ACTION: &[i8] = &[
         // State 0
@@ -148,7 +162,7 @@ mod __parse__File {
         // State 1
         0,
         // State 2
-        -35,
+        -32,
         // State 3
         0,
         // State 4
@@ -180,39 +194,39 @@ mod __parse__File {
         // State 17
         0,
         // State 18
-        -14,
+        0,
         // State 19
-        -36,
+        0,
         // State 20
-        -30,
+        0,
         // State 21
-        -13,
+        0,
         // State 22
-        -12,
+        -14,
         // State 23
         -33,
         // State 24
-        -6,
+        -29,
         // State 25
-        -3,
+        -13,
         // State 26
-        -2,
+        -12,
         // State 27
-        -15,
+        -30,
         // State 28
-        -20,
+        -6,
         // State 29
-        -5,
+        -3,
         // State 30
-        -34,
+        -2,
         // State 31
-        0,
+        -15,
         // State 32
-        0,
+        -16,
         // State 33
-        0,
+        -5,
         // State 34
-        -25,
+        -31,
         // State 35
         0,
         // State 36
@@ -220,13 +234,13 @@ mod __parse__File {
         // State 37
         0,
         // State 38
-        0,
+        -21,
         // State 39
         0,
         // State 40
         0,
         // State 41
-        -26,
+        0,
         // State 42
         0,
         // State 43
@@ -234,56 +248,74 @@ mod __parse__File {
         // State 44
         0,
         // State 45
-        -28,
+        0,
         // State 46
-        -29,
+        -22,
         // State 47
         0,
         // State 48
+        0,
+        // State 49
+        -26,
+        // State 50
+        -28,
+        // State 51
+        0,
+        // State 52
+        -25,
+        // State 53
         -27,
+        // State 54
+        0,
+        // State 55
+        -23,
+        // State 56
+        -24,
     ];
     fn __goto(state: i8, nt: usize) -> i8 {
         match nt {
-            0 => 37,
-            1 => 18,
-            2 => 38,
-            3 => 19,
-            4 => 1,
-            6 => 31,
-            7 => 20,
-            8 => 21,
-            9 => match state {
-                13 => 42,
-                _ => 35,
+            0 => match state {
+                15 => 45,
+                _ => 40,
             },
-            10 => match state {
-                17 => 47,
-                _ => 44,
+            1 => 22,
+            2 => 41,
+            3 => 23,
+            4 => 1,
+            6 => 35,
+            7 => 24,
+            8 => 25,
+            9 => match state {
+                6 => 10,
+                9 => 15,
+                11 => 16,
+                8 | 16 => 39,
+                13 | 19 => 43,
+                _ => 26,
             },
             11 => match state {
-                6 => 9,
-                10 => 13,
-                8 | 13 => 36,
-                12 => 40,
-                _ => 22,
+                16 => 19,
+                _ => 13,
             },
-            13 => 12,
-            14 => match state {
-                7 => 11,
-                11 => 14,
-                2 | 5 | 16 => 30,
-                9 => 39,
-                14 => 43,
-                _ => 23,
+            12 => match state {
+                7 => 12,
+                12 => 17,
+                2 | 5 => 34,
+                10 | 15 => 42,
+                17 => 47,
+                _ => 27,
             },
-            16 => match state {
-                0..=1 => 2,
+            13 => match state {
                 4 => 5,
-                _ => 16,
+                _ => 2,
             },
-            17 => match state {
-                1 => 29,
-                _ => 24,
+            14 => match state {
+                1 => 33,
+                14 => 44,
+                18 => 48,
+                20 => 51,
+                21 => 54,
+                _ => 28,
             },
             _ => 0,
         }
@@ -300,6 +332,7 @@ mod __parse__File {
             r###""lambda (""###,
             r###""r7rs""###,
             r###""scheme""###,
+            r###""set!""###,
             r###"r#"[0-9]+(\\.[0-9]+)?"#"###,
             r###"r#"[A-Za-z!$%&*+\\-./:<=>?@^_~][A-Za-z!$%&*+\\-./:<=>?@^_~0-9]*"#"###,
         ];
@@ -354,7 +387,7 @@ mod __parse__File {
 
         #[inline]
         fn error_action(&self, state: i8) -> i8 {
-            __action(state, 12 - 1)
+            __action(state, 13 - 1)
         }
 
         #[inline]
@@ -428,8 +461,9 @@ mod __parse__File {
             Token(9, _) if true => Some(7),
             Token(10, _) if true => Some(8),
             Token(11, _) if true => Some(9),
-            Token(0, _) if true => Some(10),
-            Token(1, _) if true => Some(11),
+            Token(12, _) if true => Some(10),
+            Token(0, _) if true => Some(11),
+            Token(1, _) if true => Some(12),
             _ => None,
         }
     }
@@ -443,8 +477,8 @@ mod __parse__File {
     ) -> __Symbol<'input>
     {
         match __token_index {
-            0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 => match __token {
-                Token(2, __tok0) | Token(3, __tok0) | Token(4, __tok0) | Token(5, __tok0) | Token(6, __tok0) | Token(7, __tok0) | Token(8, __tok0) | Token(9, __tok0) | Token(10, __tok0) | Token(11, __tok0) | Token(0, __tok0) | Token(1, __tok0) if true => __Symbol::Variant0(__tok0),
+            0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 => match __token {
+                Token(2, __tok0) | Token(3, __tok0) | Token(4, __tok0) | Token(5, __tok0) | Token(6, __tok0) | Token(7, __tok0) | Token(8, __tok0) | Token(9, __tok0) | Token(10, __tok0) | Token(11, __tok0) | Token(12, __tok0) | Token(0, __tok0) | Token(1, __tok0) if true => __Symbol::Variant0(__tok0),
                 _ => unreachable!(),
             },
             _ => unreachable!(),
@@ -593,15 +627,6 @@ mod __parse__File {
                 __reduce31(input, __lookahead_start, __symbols, core::marker::PhantomData::<(&(), &())>)
             }
             32 => {
-                __reduce32(input, __lookahead_start, __symbols, core::marker::PhantomData::<(&(), &())>)
-            }
-            33 => {
-                __reduce33(input, __lookahead_start, __symbols, core::marker::PhantomData::<(&(), &())>)
-            }
-            34 => {
-                __reduce34(input, __lookahead_start, __symbols, core::marker::PhantomData::<(&(), &())>)
-            }
-            35 => {
                 // __File = File => ActionFn(0);
                 let __sym0 = __pop_Variant3(__symbols);
                 let __start = __sym0.0.clone();
@@ -609,8 +634,8 @@ mod __parse__File {
                 let __nt = super::__action0::<>(input, __sym0);
                 return Some(Ok(__nt));
             }
-            36 => {
-                __reduce36(input, __lookahead_start, __symbols, core::marker::PhantomData::<(&(), &())>)
+            33 => {
+                __reduce33(input, __lookahead_start, __symbols, core::marker::PhantomData::<(&(), &())>)
             }
             _ => panic!("invalid action code {}", __action)
         };
@@ -662,54 +687,32 @@ mod __parse__File {
       'input,
     >(
         __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>
-    ) -> (usize, Rc<[String]>, usize)
+    ) -> (usize, String, usize)
      {
         match __symbols.pop() {
             Some((__l, __Symbol::Variant8(__v), __r)) => (__l, __v, __r),
             _ => __symbol_type_mismatch()
         }
     }
-    fn __pop_Variant9<
-      'input,
-    >(
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>
-    ) -> (usize, Rc<[Tree]>, usize)
-     {
-        match __symbols.pop() {
-            Some((__l, __Symbol::Variant9(__v), __r)) => (__l, __v, __r),
-            _ => __symbol_type_mismatch()
-        }
-    }
     fn __pop_Variant10<
       'input,
     >(
         __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>
-    ) -> (usize, String, usize)
+    ) -> (usize, Tree, usize)
      {
         match __symbols.pop() {
             Some((__l, __Symbol::Variant10(__v), __r)) => (__l, __v, __r),
             _ => __symbol_type_mismatch()
         }
     }
-    fn __pop_Variant12<
-      'input,
-    >(
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>
-    ) -> (usize, Tree, usize)
-     {
-        match __symbols.pop() {
-            Some((__l, __Symbol::Variant12(__v), __r)) => (__l, __v, __r),
-            _ => __symbol_type_mismatch()
-        }
-    }
-    fn __pop_Variant11<
+    fn __pop_Variant9<
       'input,
     >(
         __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>
     ) -> (usize, alloc::vec::Vec<String>, usize)
      {
         match __symbols.pop() {
-            Some((__l, __Symbol::Variant11(__v), __r)) => (__l, __v, __r),
+            Some((__l, __Symbol::Variant9(__v), __r)) => (__l, __v, __r),
             _ => __symbol_type_mismatch()
         }
     }
@@ -778,11 +781,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // BTree = Box<Tree> => ActionFn(10);
+        // BTree = Box<Tree> => ActionFn(11);
         let __sym0 = __pop_Variant1(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action10::<>(input, __sym0);
+        let __nt = super::__action11::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant1(__nt), __end));
         (1, 0)
     }
@@ -796,11 +799,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Bool = "#t" => ActionFn(16);
+        // Bool = "#t" => ActionFn(17);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action16::<>(input, __sym0);
+        let __nt = super::__action17::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant2(__nt), __end));
         (1, 1)
     }
@@ -814,11 +817,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Bool = "#f" => ActionFn(17);
+        // Bool = "#f" => ActionFn(18);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action17::<>(input, __sym0);
+        let __nt = super::__action18::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant2(__nt), __end));
         (1, 1)
     }
@@ -832,11 +835,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Box<Tree> = Tree => ActionFn(21);
-        let __sym0 = __pop_Variant12(__symbols);
+        // Box<Tree> = Tree => ActionFn(22);
+        let __sym0 = __pop_Variant10(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action21::<>(input, __sym0);
+        let __nt = super::__action22::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant1(__nt), __end));
         (1, 2)
     }
@@ -850,13 +853,13 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // File = Lang, Trees => ActionFn(34);
+        // File = Lang, Trees => ActionFn(31);
         assert!(__symbols.len() >= 2);
         let __sym1 = __pop_Variant3(__symbols);
         let __sym0 = __pop_Variant4(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym1.2.clone();
-        let __nt = super::__action34::<>(input, __sym0, __sym1);
+        let __nt = super::__action31::<>(input, __sym0, __sym1);
         __symbols.push((__start, __Symbol::Variant3(__nt), __end));
         (2, 3)
     }
@@ -870,11 +873,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // File = Trees => ActionFn(35);
+        // File = Trees => ActionFn(32);
         let __sym0 = __pop_Variant3(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action35::<>(input, __sym0);
+        let __nt = super::__action32::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant3(__nt), __end));
         (1, 3)
     }
@@ -888,13 +891,13 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Lang = "#lang", LangName => ActionFn(18);
+        // Lang = "#lang", LangName => ActionFn(19);
         assert!(__symbols.len() >= 2);
         let __sym1 = __pop_Variant0(__symbols);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym1.2.clone();
-        let __nt = super::__action18::<>(input, __sym0, __sym1);
+        let __nt = super::__action19::<>(input, __sym0, __sym1);
         __symbols.push((__start, __Symbol::Variant4(__nt), __end));
         (2, 4)
     }
@@ -908,11 +911,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Lang? = Lang => ActionFn(26);
+        // Lang? = Lang => ActionFn(27);
         let __sym0 = __pop_Variant4(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action26::<>(input, __sym0);
+        let __nt = super::__action27::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant5(__nt), __end));
         (1, 5)
     }
@@ -926,10 +929,10 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Lang? =  => ActionFn(27);
+        // Lang? =  => ActionFn(28);
         let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
         let __end = __start.clone();
-        let __nt = super::__action27::<>(input, &__start, &__end);
+        let __nt = super::__action28::<>(input, &__start, &__end);
         __symbols.push((__start, __Symbol::Variant5(__nt), __end));
         (0, 5)
     }
@@ -943,11 +946,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // LangName = "scheme" => ActionFn(19);
+        // LangName = "scheme" => ActionFn(20);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action19::<>(input, __sym0);
+        let __nt = super::__action20::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant0(__nt), __end));
         (1, 6)
     }
@@ -961,11 +964,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // LangName = "r7rs" => ActionFn(20);
+        // LangName = "r7rs" => ActionFn(21);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action20::<>(input, __sym0);
+        let __nt = super::__action21::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant0(__nt), __end));
         (1, 6)
     }
@@ -979,11 +982,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Literal = Sym => ActionFn(11);
-        let __sym0 = __pop_Variant10(__symbols);
+        // Literal = Sym => ActionFn(12);
+        let __sym0 = __pop_Variant8(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action11::<>(input, __sym0);
+        let __nt = super::__action12::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant6(__nt), __end));
         (1, 7)
     }
@@ -997,11 +1000,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Literal = Num => ActionFn(12);
+        // Literal = Num => ActionFn(13);
         let __sym0 = __pop_Variant7(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action12::<>(input, __sym0);
+        let __nt = super::__action13::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant6(__nt), __end));
         (1, 7)
     }
@@ -1015,11 +1018,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Literal = Bool => ActionFn(13);
+        // Literal = Bool => ActionFn(14);
         let __sym0 = __pop_Variant2(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action13::<>(input, __sym0);
+        let __nt = super::__action14::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant6(__nt), __end));
         (1, 7)
     }
@@ -1033,11 +1036,11 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Num = r#"[0-9]+(\\.[0-9]+)?"# => ActionFn(15);
+        // Num = r#"[0-9]+(\\.[0-9]+)?"# => ActionFn(16);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action15::<>(input, __sym0);
+        let __nt = super::__action16::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant7(__nt), __end));
         (1, 8)
     }
@@ -1051,12 +1054,13 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // RcSlice<Sym> =  => ActionFn(36);
-        let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
-        let __end = __start.clone();
-        let __nt = super::__action36::<>(input, &__start, &__end);
+        // Sym = r#"[A-Za-z!$%&*+\\-./:<=>?@^_~][A-Za-z!$%&*+\\-./:<=>?@^_~0-9]*"# => ActionFn(15);
+        let __sym0 = __pop_Variant0(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym0.2.clone();
+        let __nt = super::__action15::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant8(__nt), __end));
-        (0, 9)
+        (1, 9)
     }
     pub(crate) fn __reduce16<
         'input,
@@ -1068,13 +1072,12 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // RcSlice<Sym> = Sym+ => ActionFn(37);
-        let __sym0 = __pop_Variant11(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action37::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant8(__nt), __end));
-        (1, 9)
+        // Sym* =  => ActionFn(23);
+        let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
+        let __end = __start.clone();
+        let __nt = super::__action23::<>(input, &__start, &__end);
+        __symbols.push((__start, __Symbol::Variant9(__nt), __end));
+        (0, 10)
     }
     pub(crate) fn __reduce17<
         'input,
@@ -1086,12 +1089,13 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // RcSlice<Tree> =  => ActionFn(38);
-        let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
-        let __end = __start.clone();
-        let __nt = super::__action38::<>(input, &__start, &__end);
+        // Sym* = Sym+ => ActionFn(24);
+        let __sym0 = __pop_Variant9(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym0.2.clone();
+        let __nt = super::__action24::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant9(__nt), __end));
-        (0, 10)
+        (1, 10)
     }
     pub(crate) fn __reduce18<
         'input,
@@ -1103,13 +1107,13 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // RcSlice<Tree> = Tree+ => ActionFn(39);
-        let __sym0 = __pop_Variant3(__symbols);
+        // Sym+ = Sym => ActionFn(29);
+        let __sym0 = __pop_Variant8(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action39::<>(input, __sym0);
+        let __nt = super::__action29::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant9(__nt), __end));
-        (1, 10)
+        (1, 11)
     }
     pub(crate) fn __reduce19<
         'input,
@@ -1121,88 +1125,17 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Sym = r#"[A-Za-z!$%&*+\\-./:<=>?@^_~][A-Za-z!$%&*+\\-./:<=>?@^_~0-9]*"# => ActionFn(14);
-        let __sym0 = __pop_Variant0(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action14::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
-        (1, 11)
-    }
-    pub(crate) fn __reduce20<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Sym* =  => ActionFn(28);
-        let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
-        let __end = __start.clone();
-        let __nt = super::__action28::<>(input, &__start, &__end);
-        __symbols.push((__start, __Symbol::Variant11(__nt), __end));
-        (0, 12)
-    }
-    pub(crate) fn __reduce21<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Sym* = Sym+ => ActionFn(29);
-        let __sym0 = __pop_Variant11(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action29::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant11(__nt), __end));
-        (1, 12)
-    }
-    pub(crate) fn __reduce22<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Sym+ = Sym => ActionFn(32);
-        let __sym0 = __pop_Variant10(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action32::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant11(__nt), __end));
-        (1, 13)
-    }
-    pub(crate) fn __reduce23<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Sym+ = Sym+, Sym => ActionFn(33);
+        // Sym+ = Sym+, Sym => ActionFn(30);
         assert!(__symbols.len() >= 2);
-        let __sym1 = __pop_Variant10(__symbols);
-        let __sym0 = __pop_Variant11(__symbols);
+        let __sym1 = __pop_Variant8(__symbols);
+        let __sym0 = __pop_Variant9(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym1.2.clone();
-        let __nt = super::__action33::<>(input, __sym0, __sym1);
-        __symbols.push((__start, __Symbol::Variant11(__nt), __end));
-        (2, 13)
+        let __nt = super::__action30::<>(input, __sym0, __sym1);
+        __symbols.push((__start, __Symbol::Variant9(__nt), __end));
+        (2, 11)
     }
-    pub(crate) fn __reduce24<
+    pub(crate) fn __reduce20<
         'input,
         's,
     >(
@@ -1220,10 +1153,10 @@ mod __parse__File {
         let __start = __sym0.0.clone();
         let __end = __sym2.2.clone();
         let __nt = super::__action4::<>(input, __sym0, __sym1, __sym2);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (3, 14)
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (3, 12)
     }
-    pub(crate) fn __reduce25<
+    pub(crate) fn __reduce21<
         'input,
         's,
     >(
@@ -1237,16 +1170,16 @@ mod __parse__File {
         assert!(__symbols.len() >= 5);
         let __sym4 = __pop_Variant0(__symbols);
         let __sym3 = __pop_Variant1(__symbols);
-        let __sym2 = __pop_Variant10(__symbols);
+        let __sym2 = __pop_Variant8(__symbols);
         let __sym1 = __pop_Variant0(__symbols);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym4.2.clone();
         let __nt = super::__action5::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (5, 14)
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (5, 12)
     }
-    pub(crate) fn __reduce26<
+    pub(crate) fn __reduce22<
         'input,
         's,
     >(
@@ -1256,23 +1189,48 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Tree = "(", "define", "(", Sym, RcSlice<Sym>, ")", RcSlice<Tree>, ")" => ActionFn(6);
+        // Tree = "(", "define", "(", Sym, ")", Trees, ")" => ActionFn(33);
+        assert!(__symbols.len() >= 7);
+        let __sym6 = __pop_Variant0(__symbols);
+        let __sym5 = __pop_Variant3(__symbols);
+        let __sym4 = __pop_Variant0(__symbols);
+        let __sym3 = __pop_Variant8(__symbols);
+        let __sym2 = __pop_Variant0(__symbols);
+        let __sym1 = __pop_Variant0(__symbols);
+        let __sym0 = __pop_Variant0(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym6.2.clone();
+        let __nt = super::__action33::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5, __sym6);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (7, 12)
+    }
+    pub(crate) fn __reduce23<
+        'input,
+        's,
+    >(
+        input: &'input str,
+        __lookahead_start: Option<&usize>,
+        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
+        _: core::marker::PhantomData<(&'input (), &'s ())>,
+    ) -> (usize, usize)
+    {
+        // Tree = "(", "define", "(", Sym, Sym+, ")", Trees, ")" => ActionFn(34);
         assert!(__symbols.len() >= 8);
         let __sym7 = __pop_Variant0(__symbols);
-        let __sym6 = __pop_Variant9(__symbols);
+        let __sym6 = __pop_Variant3(__symbols);
         let __sym5 = __pop_Variant0(__symbols);
-        let __sym4 = __pop_Variant8(__symbols);
-        let __sym3 = __pop_Variant10(__symbols);
+        let __sym4 = __pop_Variant9(__symbols);
+        let __sym3 = __pop_Variant8(__symbols);
         let __sym2 = __pop_Variant0(__symbols);
         let __sym1 = __pop_Variant0(__symbols);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym7.2.clone();
-        let __nt = super::__action6::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5, __sym6, __sym7);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (8, 14)
+        let __nt = super::__action34::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5, __sym6, __sym7);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (8, 12)
     }
-    pub(crate) fn __reduce27<
+    pub(crate) fn __reduce24<
         'input,
         's,
     >(
@@ -1285,16 +1243,86 @@ mod __parse__File {
         // Tree = "(", "if", Tree, Tree, Tree, ")" => ActionFn(7);
         assert!(__symbols.len() >= 6);
         let __sym5 = __pop_Variant0(__symbols);
-        let __sym4 = __pop_Variant12(__symbols);
-        let __sym3 = __pop_Variant12(__symbols);
-        let __sym2 = __pop_Variant12(__symbols);
+        let __sym4 = __pop_Variant10(__symbols);
+        let __sym3 = __pop_Variant10(__symbols);
+        let __sym2 = __pop_Variant10(__symbols);
         let __sym1 = __pop_Variant0(__symbols);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym5.2.clone();
         let __nt = super::__action7::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (6, 14)
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (6, 12)
+    }
+    pub(crate) fn __reduce25<
+        'input,
+        's,
+    >(
+        input: &'input str,
+        __lookahead_start: Option<&usize>,
+        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
+        _: core::marker::PhantomData<(&'input (), &'s ())>,
+    ) -> (usize, usize)
+    {
+        // Tree = "(", "lambda (", ")", Trees, ")" => ActionFn(35);
+        assert!(__symbols.len() >= 5);
+        let __sym4 = __pop_Variant0(__symbols);
+        let __sym3 = __pop_Variant3(__symbols);
+        let __sym2 = __pop_Variant0(__symbols);
+        let __sym1 = __pop_Variant0(__symbols);
+        let __sym0 = __pop_Variant0(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym4.2.clone();
+        let __nt = super::__action35::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (5, 12)
+    }
+    pub(crate) fn __reduce26<
+        'input,
+        's,
+    >(
+        input: &'input str,
+        __lookahead_start: Option<&usize>,
+        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
+        _: core::marker::PhantomData<(&'input (), &'s ())>,
+    ) -> (usize, usize)
+    {
+        // Tree = "(", "lambda (", Sym+, ")", Trees, ")" => ActionFn(36);
+        assert!(__symbols.len() >= 6);
+        let __sym5 = __pop_Variant0(__symbols);
+        let __sym4 = __pop_Variant3(__symbols);
+        let __sym3 = __pop_Variant0(__symbols);
+        let __sym2 = __pop_Variant9(__symbols);
+        let __sym1 = __pop_Variant0(__symbols);
+        let __sym0 = __pop_Variant0(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym5.2.clone();
+        let __nt = super::__action36::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (6, 12)
+    }
+    pub(crate) fn __reduce27<
+        'input,
+        's,
+    >(
+        input: &'input str,
+        __lookahead_start: Option<&usize>,
+        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
+        _: core::marker::PhantomData<(&'input (), &'s ())>,
+    ) -> (usize, usize)
+    {
+        // Tree = "(", "set!", Sym, BTree, ")" => ActionFn(9);
+        assert!(__symbols.len() >= 5);
+        let __sym4 = __pop_Variant0(__symbols);
+        let __sym3 = __pop_Variant1(__symbols);
+        let __sym2 = __pop_Variant8(__symbols);
+        let __sym1 = __pop_Variant0(__symbols);
+        let __sym0 = __pop_Variant0(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym4.2.clone();
+        let __nt = super::__action9::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (5, 12)
     }
     pub(crate) fn __reduce28<
         'input,
@@ -1306,19 +1334,13 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Tree = "(", "lambda (", RcSlice<Sym>, ")", RcSlice<Tree>, ")" => ActionFn(8);
-        assert!(__symbols.len() >= 6);
-        let __sym5 = __pop_Variant0(__symbols);
-        let __sym4 = __pop_Variant9(__symbols);
-        let __sym3 = __pop_Variant0(__symbols);
-        let __sym2 = __pop_Variant8(__symbols);
-        let __sym1 = __pop_Variant0(__symbols);
-        let __sym0 = __pop_Variant0(__symbols);
+        // Tree = Literal => ActionFn(10);
+        let __sym0 = __pop_Variant6(__symbols);
         let __start = __sym0.0.clone();
-        let __end = __sym5.2.clone();
-        let __nt = super::__action8::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (6, 14)
+        let __end = __sym0.2.clone();
+        let __nt = super::__action10::<>(input, __sym0);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (1, 12)
     }
     pub(crate) fn __reduce29<
         'input,
@@ -1330,13 +1352,13 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Tree = Literal => ActionFn(9);
-        let __sym0 = __pop_Variant6(__symbols);
+        // Tree+ = Tree => ActionFn(25);
+        let __sym0 = __pop_Variant10(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action9::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (1, 14)
+        let __nt = super::__action25::<>(input, __sym0);
+        __symbols.push((__start, __Symbol::Variant3(__nt), __end));
+        (1, 13)
     }
     pub(crate) fn __reduce30<
         'input,
@@ -1348,70 +1370,17 @@ mod __parse__File {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Tree* =  => ActionFn(30);
-        let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
-        let __end = __start.clone();
-        let __nt = super::__action30::<>(input, &__start, &__end);
-        __symbols.push((__start, __Symbol::Variant3(__nt), __end));
-        (0, 15)
-    }
-    pub(crate) fn __reduce31<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Tree* = Tree+ => ActionFn(31);
-        let __sym0 = __pop_Variant3(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action31::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant3(__nt), __end));
-        (1, 15)
-    }
-    pub(crate) fn __reduce32<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Tree+ = Tree => ActionFn(24);
-        let __sym0 = __pop_Variant12(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action24::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant3(__nt), __end));
-        (1, 16)
-    }
-    pub(crate) fn __reduce33<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Tree+ = Tree+, Tree => ActionFn(25);
+        // Tree+ = Tree+, Tree => ActionFn(26);
         assert!(__symbols.len() >= 2);
-        let __sym1 = __pop_Variant12(__symbols);
+        let __sym1 = __pop_Variant10(__symbols);
         let __sym0 = __pop_Variant3(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym1.2.clone();
-        let __nt = super::__action25::<>(input, __sym0, __sym1);
+        let __nt = super::__action26::<>(input, __sym0, __sym1);
         __symbols.push((__start, __Symbol::Variant3(__nt), __end));
-        (2, 16)
+        (2, 13)
     }
-    pub(crate) fn __reduce34<
+    pub(crate) fn __reduce31<
         'input,
         's,
     >(
@@ -1427,9 +1396,9 @@ mod __parse__File {
         let __end = __sym0.2.clone();
         let __nt = super::__action3::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant3(__nt), __end));
-        (1, 17)
+        (1, 14)
     }
-    pub(crate) fn __reduce36<
+    pub(crate) fn __reduce33<
         'input,
         's,
     >(
@@ -1440,12 +1409,12 @@ mod __parse__File {
     ) -> (usize, usize)
     {
         // __Tree = Tree => ActionFn(1);
-        let __sym0 = __pop_Variant12(__symbols);
+        let __sym0 = __pop_Variant10(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
         let __nt = super::__action1::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (1, 19)
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (1, 16)
     }
 }
 pub(crate) use self::__parse__File::FileParser;
@@ -1474,98 +1443,114 @@ mod __parse__Tree {
         Variant5(core::option::Option<()>),
         Variant6(Literal),
         Variant7(f64),
-        Variant8(Rc<[String]>),
-        Variant9(Rc<[Tree]>),
-        Variant10(String),
-        Variant11(alloc::vec::Vec<String>),
-        Variant12(Tree),
+        Variant8(String),
+        Variant9(alloc::vec::Vec<String>),
+        Variant10(Tree),
     }
     const __ACTION: &[i8] = &[
         // State 0
-        21, 0, 22, 2, 0, 0, 0, 0, 0, 0, 23, 24,
+        26, 0, 27, 2, 0, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 1
-        21, 0, 22, 2, 0, 4, 5, 6, 0, 0, 23, 24,
+        26, 0, 27, 2, 0, 4, 5, 6, 0, 0, 7, 28, 29,
         // State 2
-        21, 0, 22, 2, 27, 0, 0, 0, 0, 0, 23, 24,
+        26, 0, 27, 2, 32, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 3
-        0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0, 24,
+        0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 0, 29,
         // State 4
-        21, 0, 22, 2, 0, 0, 0, 0, 0, 0, 23, 24,
+        26, 0, 27, 2, 0, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 5
-        0, 0, 0, 0, -16, 0, 0, 0, 0, 0, 0, 24,
+        0, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0, 29,
         // State 6
-        21, 0, 22, 2, 0, 0, 0, 0, 0, 0, 23, 24,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 29,
         // State 7
-        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 24,
+        26, 0, 27, 2, 0, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 8
-        21, 0, 22, 2, 0, 0, 0, 0, 0, 0, 23, 24,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 29,
         // State 9
-        0, 0, 0, 0, -17, 0, 0, 0, 0, 0, 0, 24,
+        26, 0, 27, 2, 0, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 10
-        0, 0, 0, 0, -16, 0, 0, 0, 0, 0, 0, 24,
+        0, 0, 0, 0, 16, 0, 0, 0, 0, 0, 0, 0, 29,
         // State 11
-        21, 0, 22, 2, 0, 0, 0, 0, 0, 0, 23, 24,
+        26, 0, 27, 2, 0, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 12
-        21, 0, 22, 2, -18, 0, 0, 0, 0, 0, 23, 24,
+        26, 0, 27, 2, 0, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 13
-        21, 0, 22, 2, -19, 0, 0, 0, 0, 0, 23, 24,
+        0, 0, 0, 0, 19, 0, 0, 0, 0, 0, 0, 0, 29,
         // State 14
-        21, 0, 22, 2, -18, 0, 0, 0, 0, 0, 23, 24,
+        26, 0, 27, 2, 0, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 15
-        -14, 0, -14, -14, -14, 0, 0, 0, 0, 0, -14, -14,
+        26, 0, 27, 2, 0, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 16
-        -30, 0, -30, -30, -30, 0, 0, 0, 0, 0, -30, -30,
+        26, 0, 27, 2, -32, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 17
-        -13, 0, -13, -13, -13, 0, 0, 0, 0, 0, -13, -13,
+        0, 0, 0, 0, 20, 0, 0, 0, 0, 0, 0, 0, 29,
         // State 18
-        -12, 0, -12, -12, -12, 0, 0, 0, 0, 0, -12, -12,
+        26, 0, 27, 2, 0, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 19
-        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        26, 0, 27, 2, 0, 0, 0, 0, 0, 0, 0, 28, 29,
         // State 20
-        -3, 0, -3, -3, -3, 0, 0, 0, 0, 0, -3, -3,
+        -14, 0, -14, -14, -14, 0, 0, 0, 0, 0, 0, -14, -14,
         // State 21
-        -2, 0, -2, -2, -2, 0, 0, 0, 0, 0, -2, -2,
+        -29, 0, -29, -29, -29, 0, 0, 0, 0, 0, 0, -29, -29,
         // State 22
-        -15, 0, -15, -15, -15, 0, 0, 0, 0, 0, -15, -15,
+        -13, 0, -13, -13, -13, 0, 0, 0, 0, 0, 0, -13, -13,
         // State 23
-        -20, 0, -20, -20, -20, 0, 0, 0, 0, 0, -20, -20,
+        -12, 0, -12, -12, -12, 0, 0, 0, 0, 0, 0, -12, -12,
         // State 24
-        -33, 0, -33, -33, -33, 0, 0, 0, 0, 0, -33, -33,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 25
-        -34, 0, -34, -34, -34, 0, 0, 0, 0, 0, -34, -34,
+        -3, 0, -3, -3, -3, 0, 0, 0, 0, 0, 0, -3, -3,
         // State 26
-        -25, 0, -25, -25, -25, 0, 0, 0, 0, 0, -25, -25,
+        -2, 0, -2, -2, -2, 0, 0, 0, 0, 0, 0, -2, -2,
         // State 27
-        0, 0, 0, 0, 13, 0, 0, 0, 0, 0, 0, 0,
+        -15, 0, -15, -15, -15, 0, 0, 0, 0, 0, 0, -15, -15,
         // State 28
-        0, 0, 0, 0, -23, 0, 0, 0, 0, 0, 0, -23,
+        -16, 0, -16, -16, -16, 0, 0, 0, 0, 0, 0, -16, -16,
         // State 29
-        0, 0, 0, 0, 34, 0, 0, 0, 0, 0, 0, 0,
+        -30, 0, -30, -30, -30, 0, 0, 0, 0, 0, 0, -30, -30,
         // State 30
-        0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0,
+        -31, 0, -31, -31, -31, 0, 0, 0, 0, 0, 0, -31, -31,
         // State 31
-        0, 0, 0, 0, -4, 0, 0, 0, 0, 0, 0, 0,
+        -21, 0, -21, -21, -21, 0, 0, 0, 0, 0, 0, -21, -21,
         // State 32
-        0, 0, 0, 0, -24, 0, 0, 0, 0, 0, 0, -24,
+        0, 0, 0, 0, -19, 0, 0, 0, 0, 0, 0, 0, -19,
         // State 33
-        -26, 0, -26, -26, -26, 0, 0, 0, 0, 0, -26, -26,
+        0, 0, 0, 0, 40, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 34
-        0, 0, 0, 0, 15, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 35
-        0, 0, 0, 0, 38, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, -4, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 36
-        0, 0, 0, 0, 39, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, -20, 0, 0, 0, 0, 0, 0, 0, -20,
         // State 37
-        -28, 0, -28, -28, -28, 0, 0, 0, 0, 0, -28, -28,
+        0, 0, 0, 0, 43, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 38
-        -29, 0, -29, -29, -29, 0, 0, 0, 0, 0, -29, -29,
+        0, 0, 0, 0, 44, 0, 0, 0, 0, 0, 0, 0, 0,
         // State 39
-        0, 0, 0, 0, 41, 0, 0, 0, 0, 0, 0, 0,
+        -22, 0, -22, -22, -22, 0, 0, 0, 0, 0, 0, -22, -22,
         // State 40
-        -27, 0, -27, -27, -27, 0, 0, 0, 0, 0, -27, -27,
+        0, 0, 0, 0, 46, 0, 0, 0, 0, 0, 0, 0, 0,
+        // State 41
+        0, 0, 0, 0, 47, 0, 0, 0, 0, 0, 0, 0, 0,
+        // State 42
+        -26, 0, -26, -26, -26, 0, 0, 0, 0, 0, 0, -26, -26,
+        // State 43
+        -28, 0, -28, -28, -28, 0, 0, 0, 0, 0, 0, -28, -28,
+        // State 44
+        0, 0, 0, 0, 49, 0, 0, 0, 0, 0, 0, 0, 0,
+        // State 45
+        -25, 0, -25, -25, -25, 0, 0, 0, 0, 0, 0, -25, -25,
+        // State 46
+        -27, 0, -27, -27, -27, 0, 0, 0, 0, 0, 0, -27, -27,
+        // State 47
+        0, 0, 0, 0, 50, 0, 0, 0, 0, 0, 0, 0, 0,
+        // State 48
+        -23, 0, -23, -23, -23, 0, 0, 0, 0, 0, 0, -23, -23,
+        // State 49
+        -24, 0, -24, -24, -24, 0, 0, 0, 0, 0, 0, -24, -24,
     ];
     fn __action(state: i8, integer: usize) -> i8 {
-        __ACTION[(state as usize) * 12 + integer]
+        __ACTION[(state as usize) * 13 + integer]
     }
     const __EOF_ACTION: &[i8] = &[
         // State 0
@@ -1599,43 +1584,43 @@ mod __parse__Tree {
         // State 14
         0,
         // State 15
-        -14,
+        0,
         // State 16
-        -30,
+        0,
         // State 17
-        -13,
+        0,
         // State 18
-        -12,
+        0,
         // State 19
-        -37,
+        0,
         // State 20
-        -3,
+        -14,
         // State 21
-        -2,
+        -29,
         // State 22
-        -15,
+        -13,
         // State 23
-        -20,
+        -12,
         // State 24
-        0,
+        -34,
         // State 25
-        0,
+        -3,
         // State 26
-        -25,
+        -2,
         // State 27
-        0,
+        -15,
         // State 28
-        0,
+        -16,
         // State 29
         0,
         // State 30
         0,
         // State 31
-        0,
+        -21,
         // State 32
         0,
         // State 33
-        -26,
+        0,
         // State 34
         0,
         // State 35
@@ -1643,49 +1628,72 @@ mod __parse__Tree {
         // State 36
         0,
         // State 37
-        -28,
-        // State 38
-        -29,
-        // State 39
         0,
+        // State 38
+        0,
+        // State 39
+        -22,
         // State 40
+        0,
+        // State 41
+        0,
+        // State 42
+        -26,
+        // State 43
+        -28,
+        // State 44
+        0,
+        // State 45
+        -25,
+        // State 46
         -27,
+        // State 47
+        0,
+        // State 48
+        -23,
+        // State 49
+        -24,
     ];
     fn __goto(state: i8, nt: usize) -> i8 {
         match nt {
-            0 => 29,
-            1 => 15,
-            2 => 30,
-            7 => 16,
-            8 => 17,
-            9 => match state {
-                10 => 34,
-                _ => 27,
+            0 => match state {
+                12 => 38,
+                _ => 33,
             },
-            10 => match state {
-                14 => 39,
-                _ => 36,
+            1 => 20,
+            2 => 34,
+            7 => 21,
+            8 => 22,
+            9 => match state {
+                3 => 7,
+                6 => 12,
+                8 => 13,
+                5 | 13 => 32,
+                10 | 17 => 36,
+                _ => 23,
             },
             11 => match state {
-                3 => 6,
-                7 => 10,
-                5 | 10 => 28,
-                9 => 32,
-                _ => 18,
+                13 => 17,
+                _ => 10,
             },
-            13 => 9,
-            14 => match state {
-                4 => 8,
-                8 => 11,
-                0 => 19,
-                2 | 13 => 25,
-                6 => 31,
-                11 => 35,
-                _ => 24,
+            12 => match state {
+                4 => 9,
+                9 => 14,
+                0 => 24,
+                2 | 16 => 30,
+                7 | 12 => 35,
+                14 => 40,
+                _ => 29,
             },
-            16 => match state {
+            13 => match state {
                 1 => 2,
-                _ => 13,
+                _ => 16,
+            },
+            14 => match state {
+                15 => 41,
+                18 => 44,
+                19 => 47,
+                _ => 37,
             },
             _ => 0,
         }
@@ -1702,6 +1710,7 @@ mod __parse__Tree {
             r###""lambda (""###,
             r###""r7rs""###,
             r###""scheme""###,
+            r###""set!""###,
             r###"r#"[0-9]+(\\.[0-9]+)?"#"###,
             r###"r#"[A-Za-z!$%&*+\\-./:<=>?@^_~][A-Za-z!$%&*+\\-./:<=>?@^_~0-9]*"#"###,
         ];
@@ -1756,7 +1765,7 @@ mod __parse__Tree {
 
         #[inline]
         fn error_action(&self, state: i8) -> i8 {
-            __action(state, 12 - 1)
+            __action(state, 13 - 1)
         }
 
         #[inline]
@@ -1830,8 +1839,9 @@ mod __parse__Tree {
             Token(9, _) if true => Some(7),
             Token(10, _) if true => Some(8),
             Token(11, _) if true => Some(9),
-            Token(0, _) if true => Some(10),
-            Token(1, _) if true => Some(11),
+            Token(12, _) if true => Some(10),
+            Token(0, _) if true => Some(11),
+            Token(1, _) if true => Some(12),
             _ => None,
         }
     }
@@ -1845,8 +1855,8 @@ mod __parse__Tree {
     ) -> __Symbol<'input>
     {
         match __token_index {
-            0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 => match __token {
-                Token(2, __tok0) | Token(3, __tok0) | Token(4, __tok0) | Token(5, __tok0) | Token(6, __tok0) | Token(7, __tok0) | Token(8, __tok0) | Token(9, __tok0) | Token(10, __tok0) | Token(11, __tok0) | Token(0, __tok0) | Token(1, __tok0) if true => __Symbol::Variant0(__tok0),
+            0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 => match __token {
+                Token(2, __tok0) | Token(3, __tok0) | Token(4, __tok0) | Token(5, __tok0) | Token(6, __tok0) | Token(7, __tok0) | Token(8, __tok0) | Token(9, __tok0) | Token(10, __tok0) | Token(11, __tok0) | Token(12, __tok0) | Token(0, __tok0) | Token(1, __tok0) if true => __Symbol::Variant0(__tok0),
                 _ => unreachable!(),
             },
             _ => unreachable!(),
@@ -1998,17 +2008,8 @@ mod __parse__Tree {
                 __reduce32(input, __lookahead_start, __symbols, core::marker::PhantomData::<(&(), &())>)
             }
             33 => {
-                __reduce33(input, __lookahead_start, __symbols, core::marker::PhantomData::<(&(), &())>)
-            }
-            34 => {
-                __reduce34(input, __lookahead_start, __symbols, core::marker::PhantomData::<(&(), &())>)
-            }
-            35 => {
-                __reduce35(input, __lookahead_start, __symbols, core::marker::PhantomData::<(&(), &())>)
-            }
-            36 => {
                 // __Tree = Tree => ActionFn(1);
-                let __sym0 = __pop_Variant12(__symbols);
+                let __sym0 = __pop_Variant10(__symbols);
                 let __start = __sym0.0.clone();
                 let __end = __sym0.2.clone();
                 let __nt = super::__action1::<>(input, __sym0);
@@ -2064,54 +2065,32 @@ mod __parse__Tree {
       'input,
     >(
         __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>
-    ) -> (usize, Rc<[String]>, usize)
+    ) -> (usize, String, usize)
      {
         match __symbols.pop() {
             Some((__l, __Symbol::Variant8(__v), __r)) => (__l, __v, __r),
             _ => __symbol_type_mismatch()
         }
     }
-    fn __pop_Variant9<
-      'input,
-    >(
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>
-    ) -> (usize, Rc<[Tree]>, usize)
-     {
-        match __symbols.pop() {
-            Some((__l, __Symbol::Variant9(__v), __r)) => (__l, __v, __r),
-            _ => __symbol_type_mismatch()
-        }
-    }
     fn __pop_Variant10<
       'input,
     >(
         __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>
-    ) -> (usize, String, usize)
+    ) -> (usize, Tree, usize)
      {
         match __symbols.pop() {
             Some((__l, __Symbol::Variant10(__v), __r)) => (__l, __v, __r),
             _ => __symbol_type_mismatch()
         }
     }
-    fn __pop_Variant12<
-      'input,
-    >(
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>
-    ) -> (usize, Tree, usize)
-     {
-        match __symbols.pop() {
-            Some((__l, __Symbol::Variant12(__v), __r)) => (__l, __v, __r),
-            _ => __symbol_type_mismatch()
-        }
-    }
-    fn __pop_Variant11<
+    fn __pop_Variant9<
       'input,
     >(
         __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>
     ) -> (usize, alloc::vec::Vec<String>, usize)
      {
         match __symbols.pop() {
-            Some((__l, __Symbol::Variant11(__v), __r)) => (__l, __v, __r),
+            Some((__l, __Symbol::Variant9(__v), __r)) => (__l, __v, __r),
             _ => __symbol_type_mismatch()
         }
     }
@@ -2180,11 +2159,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // BTree = Box<Tree> => ActionFn(10);
+        // BTree = Box<Tree> => ActionFn(11);
         let __sym0 = __pop_Variant1(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action10::<>(input, __sym0);
+        let __nt = super::__action11::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant1(__nt), __end));
         (1, 0)
     }
@@ -2198,11 +2177,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Bool = "#t" => ActionFn(16);
+        // Bool = "#t" => ActionFn(17);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action16::<>(input, __sym0);
+        let __nt = super::__action17::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant2(__nt), __end));
         (1, 1)
     }
@@ -2216,11 +2195,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Bool = "#f" => ActionFn(17);
+        // Bool = "#f" => ActionFn(18);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action17::<>(input, __sym0);
+        let __nt = super::__action18::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant2(__nt), __end));
         (1, 1)
     }
@@ -2234,11 +2213,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Box<Tree> = Tree => ActionFn(21);
-        let __sym0 = __pop_Variant12(__symbols);
+        // Box<Tree> = Tree => ActionFn(22);
+        let __sym0 = __pop_Variant10(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action21::<>(input, __sym0);
+        let __nt = super::__action22::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant1(__nt), __end));
         (1, 2)
     }
@@ -2252,13 +2231,13 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // File = Lang, Trees => ActionFn(34);
+        // File = Lang, Trees => ActionFn(31);
         assert!(__symbols.len() >= 2);
         let __sym1 = __pop_Variant3(__symbols);
         let __sym0 = __pop_Variant4(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym1.2.clone();
-        let __nt = super::__action34::<>(input, __sym0, __sym1);
+        let __nt = super::__action31::<>(input, __sym0, __sym1);
         __symbols.push((__start, __Symbol::Variant3(__nt), __end));
         (2, 3)
     }
@@ -2272,11 +2251,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // File = Trees => ActionFn(35);
+        // File = Trees => ActionFn(32);
         let __sym0 = __pop_Variant3(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action35::<>(input, __sym0);
+        let __nt = super::__action32::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant3(__nt), __end));
         (1, 3)
     }
@@ -2290,13 +2269,13 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Lang = "#lang", LangName => ActionFn(18);
+        // Lang = "#lang", LangName => ActionFn(19);
         assert!(__symbols.len() >= 2);
         let __sym1 = __pop_Variant0(__symbols);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym1.2.clone();
-        let __nt = super::__action18::<>(input, __sym0, __sym1);
+        let __nt = super::__action19::<>(input, __sym0, __sym1);
         __symbols.push((__start, __Symbol::Variant4(__nt), __end));
         (2, 4)
     }
@@ -2310,11 +2289,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Lang? = Lang => ActionFn(26);
+        // Lang? = Lang => ActionFn(27);
         let __sym0 = __pop_Variant4(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action26::<>(input, __sym0);
+        let __nt = super::__action27::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant5(__nt), __end));
         (1, 5)
     }
@@ -2328,10 +2307,10 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Lang? =  => ActionFn(27);
+        // Lang? =  => ActionFn(28);
         let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
         let __end = __start.clone();
-        let __nt = super::__action27::<>(input, &__start, &__end);
+        let __nt = super::__action28::<>(input, &__start, &__end);
         __symbols.push((__start, __Symbol::Variant5(__nt), __end));
         (0, 5)
     }
@@ -2345,11 +2324,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // LangName = "scheme" => ActionFn(19);
+        // LangName = "scheme" => ActionFn(20);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action19::<>(input, __sym0);
+        let __nt = super::__action20::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant0(__nt), __end));
         (1, 6)
     }
@@ -2363,11 +2342,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // LangName = "r7rs" => ActionFn(20);
+        // LangName = "r7rs" => ActionFn(21);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action20::<>(input, __sym0);
+        let __nt = super::__action21::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant0(__nt), __end));
         (1, 6)
     }
@@ -2381,11 +2360,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Literal = Sym => ActionFn(11);
-        let __sym0 = __pop_Variant10(__symbols);
+        // Literal = Sym => ActionFn(12);
+        let __sym0 = __pop_Variant8(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action11::<>(input, __sym0);
+        let __nt = super::__action12::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant6(__nt), __end));
         (1, 7)
     }
@@ -2399,11 +2378,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Literal = Num => ActionFn(12);
+        // Literal = Num => ActionFn(13);
         let __sym0 = __pop_Variant7(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action12::<>(input, __sym0);
+        let __nt = super::__action13::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant6(__nt), __end));
         (1, 7)
     }
@@ -2417,11 +2396,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Literal = Bool => ActionFn(13);
+        // Literal = Bool => ActionFn(14);
         let __sym0 = __pop_Variant2(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action13::<>(input, __sym0);
+        let __nt = super::__action14::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant6(__nt), __end));
         (1, 7)
     }
@@ -2435,11 +2414,11 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Num = r#"[0-9]+(\\.[0-9]+)?"# => ActionFn(15);
+        // Num = r#"[0-9]+(\\.[0-9]+)?"# => ActionFn(16);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action15::<>(input, __sym0);
+        let __nt = super::__action16::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant7(__nt), __end));
         (1, 8)
     }
@@ -2453,12 +2432,13 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // RcSlice<Sym> =  => ActionFn(36);
-        let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
-        let __end = __start.clone();
-        let __nt = super::__action36::<>(input, &__start, &__end);
+        // Sym = r#"[A-Za-z!$%&*+\\-./:<=>?@^_~][A-Za-z!$%&*+\\-./:<=>?@^_~0-9]*"# => ActionFn(15);
+        let __sym0 = __pop_Variant0(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym0.2.clone();
+        let __nt = super::__action15::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant8(__nt), __end));
-        (0, 9)
+        (1, 9)
     }
     pub(crate) fn __reduce16<
         'input,
@@ -2470,13 +2450,12 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // RcSlice<Sym> = Sym+ => ActionFn(37);
-        let __sym0 = __pop_Variant11(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action37::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant8(__nt), __end));
-        (1, 9)
+        // Sym* =  => ActionFn(23);
+        let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
+        let __end = __start.clone();
+        let __nt = super::__action23::<>(input, &__start, &__end);
+        __symbols.push((__start, __Symbol::Variant9(__nt), __end));
+        (0, 10)
     }
     pub(crate) fn __reduce17<
         'input,
@@ -2488,12 +2467,13 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // RcSlice<Tree> =  => ActionFn(38);
-        let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
-        let __end = __start.clone();
-        let __nt = super::__action38::<>(input, &__start, &__end);
+        // Sym* = Sym+ => ActionFn(24);
+        let __sym0 = __pop_Variant9(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym0.2.clone();
+        let __nt = super::__action24::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant9(__nt), __end));
-        (0, 10)
+        (1, 10)
     }
     pub(crate) fn __reduce18<
         'input,
@@ -2505,13 +2485,13 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // RcSlice<Tree> = Tree+ => ActionFn(39);
-        let __sym0 = __pop_Variant3(__symbols);
+        // Sym+ = Sym => ActionFn(29);
+        let __sym0 = __pop_Variant8(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action39::<>(input, __sym0);
+        let __nt = super::__action29::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant9(__nt), __end));
-        (1, 10)
+        (1, 11)
     }
     pub(crate) fn __reduce19<
         'input,
@@ -2523,88 +2503,17 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Sym = r#"[A-Za-z!$%&*+\\-./:<=>?@^_~][A-Za-z!$%&*+\\-./:<=>?@^_~0-9]*"# => ActionFn(14);
-        let __sym0 = __pop_Variant0(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action14::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
-        (1, 11)
-    }
-    pub(crate) fn __reduce20<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Sym* =  => ActionFn(28);
-        let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
-        let __end = __start.clone();
-        let __nt = super::__action28::<>(input, &__start, &__end);
-        __symbols.push((__start, __Symbol::Variant11(__nt), __end));
-        (0, 12)
-    }
-    pub(crate) fn __reduce21<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Sym* = Sym+ => ActionFn(29);
-        let __sym0 = __pop_Variant11(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action29::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant11(__nt), __end));
-        (1, 12)
-    }
-    pub(crate) fn __reduce22<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Sym+ = Sym => ActionFn(32);
-        let __sym0 = __pop_Variant10(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action32::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant11(__nt), __end));
-        (1, 13)
-    }
-    pub(crate) fn __reduce23<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Sym+ = Sym+, Sym => ActionFn(33);
+        // Sym+ = Sym+, Sym => ActionFn(30);
         assert!(__symbols.len() >= 2);
-        let __sym1 = __pop_Variant10(__symbols);
-        let __sym0 = __pop_Variant11(__symbols);
+        let __sym1 = __pop_Variant8(__symbols);
+        let __sym0 = __pop_Variant9(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym1.2.clone();
-        let __nt = super::__action33::<>(input, __sym0, __sym1);
-        __symbols.push((__start, __Symbol::Variant11(__nt), __end));
-        (2, 13)
+        let __nt = super::__action30::<>(input, __sym0, __sym1);
+        __symbols.push((__start, __Symbol::Variant9(__nt), __end));
+        (2, 11)
     }
-    pub(crate) fn __reduce24<
+    pub(crate) fn __reduce20<
         'input,
         's,
     >(
@@ -2622,10 +2531,10 @@ mod __parse__Tree {
         let __start = __sym0.0.clone();
         let __end = __sym2.2.clone();
         let __nt = super::__action4::<>(input, __sym0, __sym1, __sym2);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (3, 14)
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (3, 12)
     }
-    pub(crate) fn __reduce25<
+    pub(crate) fn __reduce21<
         'input,
         's,
     >(
@@ -2639,16 +2548,16 @@ mod __parse__Tree {
         assert!(__symbols.len() >= 5);
         let __sym4 = __pop_Variant0(__symbols);
         let __sym3 = __pop_Variant1(__symbols);
-        let __sym2 = __pop_Variant10(__symbols);
+        let __sym2 = __pop_Variant8(__symbols);
         let __sym1 = __pop_Variant0(__symbols);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym4.2.clone();
         let __nt = super::__action5::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (5, 14)
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (5, 12)
     }
-    pub(crate) fn __reduce26<
+    pub(crate) fn __reduce22<
         'input,
         's,
     >(
@@ -2658,23 +2567,48 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Tree = "(", "define", "(", Sym, RcSlice<Sym>, ")", RcSlice<Tree>, ")" => ActionFn(6);
+        // Tree = "(", "define", "(", Sym, ")", Trees, ")" => ActionFn(33);
+        assert!(__symbols.len() >= 7);
+        let __sym6 = __pop_Variant0(__symbols);
+        let __sym5 = __pop_Variant3(__symbols);
+        let __sym4 = __pop_Variant0(__symbols);
+        let __sym3 = __pop_Variant8(__symbols);
+        let __sym2 = __pop_Variant0(__symbols);
+        let __sym1 = __pop_Variant0(__symbols);
+        let __sym0 = __pop_Variant0(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym6.2.clone();
+        let __nt = super::__action33::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5, __sym6);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (7, 12)
+    }
+    pub(crate) fn __reduce23<
+        'input,
+        's,
+    >(
+        input: &'input str,
+        __lookahead_start: Option<&usize>,
+        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
+        _: core::marker::PhantomData<(&'input (), &'s ())>,
+    ) -> (usize, usize)
+    {
+        // Tree = "(", "define", "(", Sym, Sym+, ")", Trees, ")" => ActionFn(34);
         assert!(__symbols.len() >= 8);
         let __sym7 = __pop_Variant0(__symbols);
-        let __sym6 = __pop_Variant9(__symbols);
+        let __sym6 = __pop_Variant3(__symbols);
         let __sym5 = __pop_Variant0(__symbols);
-        let __sym4 = __pop_Variant8(__symbols);
-        let __sym3 = __pop_Variant10(__symbols);
+        let __sym4 = __pop_Variant9(__symbols);
+        let __sym3 = __pop_Variant8(__symbols);
         let __sym2 = __pop_Variant0(__symbols);
         let __sym1 = __pop_Variant0(__symbols);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym7.2.clone();
-        let __nt = super::__action6::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5, __sym6, __sym7);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (8, 14)
+        let __nt = super::__action34::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5, __sym6, __sym7);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (8, 12)
     }
-    pub(crate) fn __reduce27<
+    pub(crate) fn __reduce24<
         'input,
         's,
     >(
@@ -2687,16 +2621,86 @@ mod __parse__Tree {
         // Tree = "(", "if", Tree, Tree, Tree, ")" => ActionFn(7);
         assert!(__symbols.len() >= 6);
         let __sym5 = __pop_Variant0(__symbols);
-        let __sym4 = __pop_Variant12(__symbols);
-        let __sym3 = __pop_Variant12(__symbols);
-        let __sym2 = __pop_Variant12(__symbols);
+        let __sym4 = __pop_Variant10(__symbols);
+        let __sym3 = __pop_Variant10(__symbols);
+        let __sym2 = __pop_Variant10(__symbols);
         let __sym1 = __pop_Variant0(__symbols);
         let __sym0 = __pop_Variant0(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym5.2.clone();
         let __nt = super::__action7::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (6, 14)
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (6, 12)
+    }
+    pub(crate) fn __reduce25<
+        'input,
+        's,
+    >(
+        input: &'input str,
+        __lookahead_start: Option<&usize>,
+        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
+        _: core::marker::PhantomData<(&'input (), &'s ())>,
+    ) -> (usize, usize)
+    {
+        // Tree = "(", "lambda (", ")", Trees, ")" => ActionFn(35);
+        assert!(__symbols.len() >= 5);
+        let __sym4 = __pop_Variant0(__symbols);
+        let __sym3 = __pop_Variant3(__symbols);
+        let __sym2 = __pop_Variant0(__symbols);
+        let __sym1 = __pop_Variant0(__symbols);
+        let __sym0 = __pop_Variant0(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym4.2.clone();
+        let __nt = super::__action35::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (5, 12)
+    }
+    pub(crate) fn __reduce26<
+        'input,
+        's,
+    >(
+        input: &'input str,
+        __lookahead_start: Option<&usize>,
+        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
+        _: core::marker::PhantomData<(&'input (), &'s ())>,
+    ) -> (usize, usize)
+    {
+        // Tree = "(", "lambda (", Sym+, ")", Trees, ")" => ActionFn(36);
+        assert!(__symbols.len() >= 6);
+        let __sym5 = __pop_Variant0(__symbols);
+        let __sym4 = __pop_Variant3(__symbols);
+        let __sym3 = __pop_Variant0(__symbols);
+        let __sym2 = __pop_Variant9(__symbols);
+        let __sym1 = __pop_Variant0(__symbols);
+        let __sym0 = __pop_Variant0(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym5.2.clone();
+        let __nt = super::__action36::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (6, 12)
+    }
+    pub(crate) fn __reduce27<
+        'input,
+        's,
+    >(
+        input: &'input str,
+        __lookahead_start: Option<&usize>,
+        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
+        _: core::marker::PhantomData<(&'input (), &'s ())>,
+    ) -> (usize, usize)
+    {
+        // Tree = "(", "set!", Sym, BTree, ")" => ActionFn(9);
+        assert!(__symbols.len() >= 5);
+        let __sym4 = __pop_Variant0(__symbols);
+        let __sym3 = __pop_Variant1(__symbols);
+        let __sym2 = __pop_Variant8(__symbols);
+        let __sym1 = __pop_Variant0(__symbols);
+        let __sym0 = __pop_Variant0(__symbols);
+        let __start = __sym0.0.clone();
+        let __end = __sym4.2.clone();
+        let __nt = super::__action9::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (5, 12)
     }
     pub(crate) fn __reduce28<
         'input,
@@ -2708,19 +2712,13 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Tree = "(", "lambda (", RcSlice<Sym>, ")", RcSlice<Tree>, ")" => ActionFn(8);
-        assert!(__symbols.len() >= 6);
-        let __sym5 = __pop_Variant0(__symbols);
-        let __sym4 = __pop_Variant9(__symbols);
-        let __sym3 = __pop_Variant0(__symbols);
-        let __sym2 = __pop_Variant8(__symbols);
-        let __sym1 = __pop_Variant0(__symbols);
-        let __sym0 = __pop_Variant0(__symbols);
+        // Tree = Literal => ActionFn(10);
+        let __sym0 = __pop_Variant6(__symbols);
         let __start = __sym0.0.clone();
-        let __end = __sym5.2.clone();
-        let __nt = super::__action8::<>(input, __sym0, __sym1, __sym2, __sym3, __sym4, __sym5);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (6, 14)
+        let __end = __sym0.2.clone();
+        let __nt = super::__action10::<>(input, __sym0);
+        __symbols.push((__start, __Symbol::Variant10(__nt), __end));
+        (1, 12)
     }
     pub(crate) fn __reduce29<
         'input,
@@ -2732,13 +2730,13 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Tree = Literal => ActionFn(9);
-        let __sym0 = __pop_Variant6(__symbols);
+        // Tree+ = Tree => ActionFn(25);
+        let __sym0 = __pop_Variant10(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym0.2.clone();
-        let __nt = super::__action9::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant12(__nt), __end));
-        (1, 14)
+        let __nt = super::__action25::<>(input, __sym0);
+        __symbols.push((__start, __Symbol::Variant3(__nt), __end));
+        (1, 13)
     }
     pub(crate) fn __reduce30<
         'input,
@@ -2750,70 +2748,17 @@ mod __parse__Tree {
         _: core::marker::PhantomData<(&'input (), &'s ())>,
     ) -> (usize, usize)
     {
-        // Tree* =  => ActionFn(30);
-        let __start = __lookahead_start.cloned().or_else(|| __symbols.last().map(|s| s.2.clone())).unwrap_or_default();
-        let __end = __start.clone();
-        let __nt = super::__action30::<>(input, &__start, &__end);
-        __symbols.push((__start, __Symbol::Variant3(__nt), __end));
-        (0, 15)
-    }
-    pub(crate) fn __reduce31<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Tree* = Tree+ => ActionFn(31);
-        let __sym0 = __pop_Variant3(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action31::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant3(__nt), __end));
-        (1, 15)
-    }
-    pub(crate) fn __reduce32<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Tree+ = Tree => ActionFn(24);
-        let __sym0 = __pop_Variant12(__symbols);
-        let __start = __sym0.0.clone();
-        let __end = __sym0.2.clone();
-        let __nt = super::__action24::<>(input, __sym0);
-        __symbols.push((__start, __Symbol::Variant3(__nt), __end));
-        (1, 16)
-    }
-    pub(crate) fn __reduce33<
-        'input,
-        's,
-    >(
-        input: &'input str,
-        __lookahead_start: Option<&usize>,
-        __symbols: &mut alloc::vec::Vec<(usize,__Symbol<'input>,usize)>,
-        _: core::marker::PhantomData<(&'input (), &'s ())>,
-    ) -> (usize, usize)
-    {
-        // Tree+ = Tree+, Tree => ActionFn(25);
+        // Tree+ = Tree+, Tree => ActionFn(26);
         assert!(__symbols.len() >= 2);
-        let __sym1 = __pop_Variant12(__symbols);
+        let __sym1 = __pop_Variant10(__symbols);
         let __sym0 = __pop_Variant3(__symbols);
         let __start = __sym0.0.clone();
         let __end = __sym1.2.clone();
-        let __nt = super::__action25::<>(input, __sym0, __sym1);
+        let __nt = super::__action26::<>(input, __sym0, __sym1);
         __symbols.push((__start, __Symbol::Variant3(__nt), __end));
-        (2, 16)
+        (2, 13)
     }
-    pub(crate) fn __reduce34<
+    pub(crate) fn __reduce31<
         'input,
         's,
     >(
@@ -2829,9 +2774,9 @@ mod __parse__Tree {
         let __end = __sym0.2.clone();
         let __nt = super::__action3::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant3(__nt), __end));
-        (1, 17)
+        (1, 14)
     }
-    pub(crate) fn __reduce35<
+    pub(crate) fn __reduce32<
         'input,
         's,
     >(
@@ -2847,7 +2792,7 @@ mod __parse__Tree {
         let __end = __sym0.2.clone();
         let __nt = super::__action0::<>(input, __sym0);
         __symbols.push((__start, __Symbol::Variant3(__nt), __end));
-        (1, 18)
+        (1, 15)
     }
 }
 pub(crate) use self::__parse__Tree::TreeParser;
@@ -2876,6 +2821,7 @@ mod __intern_token {
             ("^(lambda \\()", false),
             ("^(r7rs)", false),
             ("^(scheme)", false),
+            ("^(set!)", false),
             ("^(;[\u{0}-\t\u{b}-\u{c}\u{e}-\u{10ffff}]*[\n\r]*)", true),
             ("^([\t-\r \u{85}\u{a0}\u{1680}\u{2000}-\u{200a}\u{2028}-\u{2029}\u{202f}\u{205f}\u{3000}]*)", true),
         ];
@@ -2885,74 +2831,108 @@ mod __intern_token {
 pub(crate) use self::__lalrpop_util::lexer::Token;
 
 #[allow(unused_variables)]
-fn __action0<'input, 's>(
+fn __action0<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, __0, _): (usize, alloc::vec::Vec<Tree>, usize),
-) -> alloc::vec::Vec<Tree> {
+) -> alloc::vec::Vec<Tree>
+{
     __0
 }
 
 #[allow(unused_variables)]
-fn __action1<'input, 's>(input: &'input str, (_, __0, _): (usize, Tree, usize)) -> Tree {
+fn __action1<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, __0, _): (usize, Tree, usize),
+) -> Tree
+{
     __0
 }
 
 #[allow(unused_variables)]
-fn __action2<'input, 's>(
+fn __action2<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, _, _): (usize, core::option::Option<()>, usize),
     (_, __0, _): (usize, alloc::vec::Vec<Tree>, usize),
-) -> alloc::vec::Vec<Tree> {
+) -> alloc::vec::Vec<Tree>
+{
     __0
 }
 
 #[allow(unused_variables)]
-fn __action3<'input, 's>(
+fn __action3<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, __0, _): (usize, alloc::vec::Vec<Tree>, usize),
-) -> alloc::vec::Vec<Tree> {
+) -> alloc::vec::Vec<Tree>
+{
     __0
 }
 
 #[allow(unused_variables)]
-fn __action4<'input, 's>(
+fn __action4<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, _, _): (usize, &'input str, usize),
     (_, __0, _): (usize, alloc::vec::Vec<Tree>, usize),
     (_, _, _): (usize, &'input str, usize),
-) -> Tree {
+) -> Tree
+{
     Tree::Branch(__0)
 }
 
 #[allow(unused_variables)]
-fn __action5<'input, 's>(
+fn __action5<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, _, _): (usize, &'input str, usize),
     (_, _, _): (usize, &'input str, usize),
     (_, __0, _): (usize, String, usize),
     (_, __1, _): (usize, Box<Tree>, usize),
     (_, _, _): (usize, &'input str, usize),
-) -> Tree {
+) -> Tree
+{
     Tree::Define(__0, __1)
 }
 
 #[allow(unused_variables)]
-fn __action6<'input, 's>(
+fn __action6<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, _, _): (usize, &'input str, usize),
     (_, _, _): (usize, &'input str, usize),
     (_, _, _): (usize, &'input str, usize),
     (_, name, _): (usize, String, usize),
-    (_, args, _): (usize, Rc<[String]>, usize),
+    (_, args, _): (usize, alloc::vec::Vec<String>, usize),
     (_, _, _): (usize, &'input str, usize),
-    (_, body, _): (usize, Rc<[Tree]>, usize),
+    (_, body, _): (usize, alloc::vec::Vec<Tree>, usize),
     (_, _, _): (usize, &'input str, usize),
-) -> Tree {
-    Tree::Define(name, Box::new(Tree::Lambda(Lambda(args, body))))
+) -> Tree
+{
+    Tree::Define(name, Box::new(Tree::Func(Rc::new(Func{args, body}))))
 }
 
 #[allow(unused_variables)]
-fn __action7<'input, 's>(
+fn __action7<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, _, _): (usize, &'input str, usize),
     (_, _, _): (usize, &'input str, usize),
@@ -2960,308 +2940,496 @@ fn __action7<'input, 's>(
     (_, __1, _): (usize, Tree, usize),
     (_, __2, _): (usize, Tree, usize),
     (_, _, _): (usize, &'input str, usize),
-) -> Tree {
+) -> Tree
+{
     Tree::If(Box::new([__0, __1, __2]))
 }
 
 #[allow(unused_variables)]
-fn __action8<'input, 's>(
+fn __action8<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, _, _): (usize, &'input str, usize),
     (_, _, _): (usize, &'input str, usize),
-    (_, __0, _): (usize, Rc<[String]>, usize),
+    (_, args, _): (usize, alloc::vec::Vec<String>, usize),
     (_, _, _): (usize, &'input str, usize),
-    (_, __1, _): (usize, Rc<[Tree]>, usize),
+    (_, body, _): (usize, alloc::vec::Vec<Tree>, usize),
     (_, _, _): (usize, &'input str, usize),
-) -> Tree {
-    Tree::Lambda(Lambda(__0, __1))
+) -> Tree
+{
+    Tree::Func(Rc::new(Func{args:args, body:body}))
 }
 
 #[allow(unused_variables)]
-fn __action9<'input, 's>(input: &'input str, (_, __0, _): (usize, Literal, usize)) -> Tree {
+fn __action9<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, _, _): (usize, &'input str, usize),
+    (_, _, _): (usize, &'input str, usize),
+    (_, __0, _): (usize, String, usize),
+    (_, __1, _): (usize, Box<Tree>, usize),
+    (_, _, _): (usize, &'input str, usize),
+) -> Tree
+{
+    Tree::Set(__0, __1)
+}
+
+#[allow(unused_variables)]
+fn __action10<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, __0, _): (usize, Literal, usize),
+) -> Tree
+{
     Tree::Leaf(__0)
 }
 
 #[allow(unused_variables)]
-fn __action10<'input, 's>(input: &'input str, (_, __0, _): (usize, Box<Tree>, usize)) -> Box<Tree> {
+fn __action11<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, __0, _): (usize, Box<Tree>, usize),
+) -> Box<Tree>
+{
     __0
 }
 
 #[allow(unused_variables)]
-fn __action11<'input, 's>(input: &'input str, (_, __0, _): (usize, String, usize)) -> Literal {
+fn __action12<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, __0, _): (usize, String, usize),
+) -> Literal
+{
     Literal::Sym(__0)
 }
 
 #[allow(unused_variables)]
-fn __action12<'input, 's>(input: &'input str, (_, __0, _): (usize, f64, usize)) -> Literal {
+fn __action13<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, __0, _): (usize, f64, usize),
+) -> Literal
+{
     Literal::Num(__0)
 }
 
 #[allow(unused_variables)]
-fn __action13<'input, 's>(input: &'input str, (_, __0, _): (usize, bool, usize)) -> Literal {
+fn __action14<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, __0, _): (usize, bool, usize),
+) -> Literal
+{
     Literal::Bool(__0)
 }
 
 #[allow(unused_variables)]
-fn __action14<'input, 's>(input: &'input str, (_, __0, _): (usize, &'input str, usize)) -> String {
+fn __action15<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, __0, _): (usize, &'input str, usize),
+) -> String
+{
     __0.to_owned()
 }
 
 #[allow(unused_variables)]
-fn __action15<'input, 's>(input: &'input str, (_, __0, _): (usize, &'input str, usize)) -> f64 {
+fn __action16<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, __0, _): (usize, &'input str, usize),
+) -> f64
+{
     __0.parse().unwrap()
 }
 
 #[allow(unused_variables)]
-fn __action16<'input, 's>(input: &'input str, (_, __0, _): (usize, &'input str, usize)) -> bool {
+fn __action17<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, __0, _): (usize, &'input str, usize),
+) -> bool
+{
     true
 }
 
 #[allow(unused_variables)]
-fn __action17<'input, 's>(input: &'input str, (_, __0, _): (usize, &'input str, usize)) -> bool {
+fn __action18<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, __0, _): (usize, &'input str, usize),
+) -> bool
+{
     false
 }
 
 #[allow(unused_variables)]
-fn __action18<'input, 's>(
+fn __action19<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, __0, _): (usize, &'input str, usize),
     (_, __1, _): (usize, &'input str, usize),
-) -> () {
+) -> ()
+{
     ()
 }
 
 #[allow(unused_variables)]
-fn __action19<'input, 's>(
+fn __action20<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, __0, _): (usize, &'input str, usize),
-) -> &'input str {
+) -> &'input str
+{
     __0
 }
 
 #[allow(unused_variables)]
-fn __action20<'input, 's>(
+fn __action21<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, __0, _): (usize, &'input str, usize),
-) -> &'input str {
+) -> &'input str
+{
     __0
 }
 
 #[allow(unused_variables)]
-fn __action21<'input, 's>(input: &'input str, (_, __0, _): (usize, Tree, usize)) -> Box<Tree> {
+fn __action22<
+    'input,
+    's,
+>(
+    input: &'input str,
+    (_, __0, _): (usize, Tree, usize),
+) -> Box<Tree>
+{
     Box::new(__0)
 }
 
 #[allow(unused_variables)]
-fn __action22<'input, 's>(
+fn __action23<
+    'input,
+    's,
+>(
     input: &'input str,
-    (_, __0, _): (usize, alloc::vec::Vec<Tree>, usize),
-) -> Rc<[Tree]> {
-    __0.into()
+    __lookbehind: &usize,
+    __lookahead: &usize,
+) -> alloc::vec::Vec<String>
+{
+    alloc::vec![]
 }
 
 #[allow(unused_variables)]
-fn __action23<'input, 's>(
+fn __action24<
+    'input,
+    's,
+>(
     input: &'input str,
-    (_, __0, _): (usize, alloc::vec::Vec<String>, usize),
-) -> Rc<[String]> {
-    __0.into()
+    (_, v, _): (usize, alloc::vec::Vec<String>, usize),
+) -> alloc::vec::Vec<String>
+{
+    v
 }
 
 #[allow(unused_variables)]
-fn __action24<'input, 's>(
+fn __action25<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, __0, _): (usize, Tree, usize),
-) -> alloc::vec::Vec<Tree> {
+) -> alloc::vec::Vec<Tree>
+{
     alloc::vec![__0]
 }
 
 #[allow(unused_variables)]
-fn __action25<'input, 's>(
+fn __action26<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, v, _): (usize, alloc::vec::Vec<Tree>, usize),
     (_, e, _): (usize, Tree, usize),
-) -> alloc::vec::Vec<Tree> {
-    {
-        let mut v = v;
-        v.push(e);
-        v
-    }
+) -> alloc::vec::Vec<Tree>
+{
+    { let mut v = v; v.push(e); v }
 }
 
 #[allow(unused_variables)]
-fn __action26<'input, 's>(
+fn __action27<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, __0, _): (usize, (), usize),
-) -> core::option::Option<()> {
+) -> core::option::Option<()>
+{
     Some(__0)
 }
 
 #[allow(unused_variables)]
-fn __action27<'input, 's>(
+fn __action28<
+    'input,
+    's,
+>(
     input: &'input str,
     __lookbehind: &usize,
     __lookahead: &usize,
-) -> core::option::Option<()> {
+) -> core::option::Option<()>
+{
     None
 }
 
 #[allow(unused_variables)]
-fn __action28<'input, 's>(
-    input: &'input str,
-    __lookbehind: &usize,
-    __lookahead: &usize,
-) -> alloc::vec::Vec<String> {
-    alloc::vec![]
-}
-
-#[allow(unused_variables)]
-fn __action29<'input, 's>(
-    input: &'input str,
-    (_, v, _): (usize, alloc::vec::Vec<String>, usize),
-) -> alloc::vec::Vec<String> {
-    v
-}
-
-#[allow(unused_variables)]
-fn __action30<'input, 's>(
-    input: &'input str,
-    __lookbehind: &usize,
-    __lookahead: &usize,
-) -> alloc::vec::Vec<Tree> {
-    alloc::vec![]
-}
-
-#[allow(unused_variables)]
-fn __action31<'input, 's>(
-    input: &'input str,
-    (_, v, _): (usize, alloc::vec::Vec<Tree>, usize),
-) -> alloc::vec::Vec<Tree> {
-    v
-}
-
-#[allow(unused_variables)]
-fn __action32<'input, 's>(
+fn __action29<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, __0, _): (usize, String, usize),
-) -> alloc::vec::Vec<String> {
+) -> alloc::vec::Vec<String>
+{
     alloc::vec![__0]
 }
 
 #[allow(unused_variables)]
-fn __action33<'input, 's>(
+fn __action30<
+    'input,
+    's,
+>(
     input: &'input str,
     (_, v, _): (usize, alloc::vec::Vec<String>, usize),
     (_, e, _): (usize, String, usize),
-) -> alloc::vec::Vec<String> {
-    {
-        let mut v = v;
-        v.push(e);
-        v
-    }
+) -> alloc::vec::Vec<String>
+{
+    { let mut v = v; v.push(e); v }
 }
 
 #[allow(unused_variables)]
-fn __action34<'input, 's>(
+fn __action31<
+    'input,
+    's,
+>(
     input: &'input str,
     __0: (usize, (), usize),
     __1: (usize, alloc::vec::Vec<Tree>, usize),
-) -> alloc::vec::Vec<Tree> {
+) -> alloc::vec::Vec<Tree>
+{
     let __start0 = __0.0.clone();
     let __end0 = __0.2.clone();
-    let __temp0 = __action26(input, __0);
+    let __temp0 = __action27(
+        input,
+        __0,
+    );
     let __temp0 = (__start0, __temp0, __end0);
-    __action2(input, __temp0, __1)
+    __action2(
+        input,
+        __temp0,
+        __1,
+    )
 }
 
 #[allow(unused_variables)]
-fn __action35<'input, 's>(
+fn __action32<
+    'input,
+    's,
+>(
     input: &'input str,
     __0: (usize, alloc::vec::Vec<Tree>, usize),
-) -> alloc::vec::Vec<Tree> {
+) -> alloc::vec::Vec<Tree>
+{
     let __start0 = __0.0.clone();
     let __end0 = __0.0.clone();
-    let __temp0 = __action27(input, &__start0, &__end0);
+    let __temp0 = __action28(
+        input,
+        &__start0,
+        &__end0,
+    );
     let __temp0 = (__start0, __temp0, __end0);
-    __action2(input, __temp0, __0)
+    __action2(
+        input,
+        __temp0,
+        __0,
+    )
 }
 
 #[allow(unused_variables)]
-fn __action36<'input, 's>(
+fn __action33<
+    'input,
+    's,
+>(
     input: &'input str,
-    __lookbehind: &usize,
-    __lookahead: &usize,
-) -> Rc<[String]> {
-    let __start0 = __lookbehind.clone();
-    let __end0 = __lookahead.clone();
-    let __temp0 = __action28(input, &__start0, &__end0);
+    __0: (usize, &'input str, usize),
+    __1: (usize, &'input str, usize),
+    __2: (usize, &'input str, usize),
+    __3: (usize, String, usize),
+    __4: (usize, &'input str, usize),
+    __5: (usize, alloc::vec::Vec<Tree>, usize),
+    __6: (usize, &'input str, usize),
+) -> Tree
+{
+    let __start0 = __3.2.clone();
+    let __end0 = __4.0.clone();
+    let __temp0 = __action23(
+        input,
+        &__start0,
+        &__end0,
+    );
     let __temp0 = (__start0, __temp0, __end0);
-    __action23(input, __temp0)
+    __action6(
+        input,
+        __0,
+        __1,
+        __2,
+        __3,
+        __temp0,
+        __4,
+        __5,
+        __6,
+    )
 }
 
 #[allow(unused_variables)]
-fn __action37<'input, 's>(
+fn __action34<
+    'input,
+    's,
+>(
     input: &'input str,
-    __0: (usize, alloc::vec::Vec<String>, usize),
-) -> Rc<[String]> {
-    let __start0 = __0.0.clone();
-    let __end0 = __0.2.clone();
-    let __temp0 = __action29(input, __0);
+    __0: (usize, &'input str, usize),
+    __1: (usize, &'input str, usize),
+    __2: (usize, &'input str, usize),
+    __3: (usize, String, usize),
+    __4: (usize, alloc::vec::Vec<String>, usize),
+    __5: (usize, &'input str, usize),
+    __6: (usize, alloc::vec::Vec<Tree>, usize),
+    __7: (usize, &'input str, usize),
+) -> Tree
+{
+    let __start0 = __4.0.clone();
+    let __end0 = __4.2.clone();
+    let __temp0 = __action24(
+        input,
+        __4,
+    );
     let __temp0 = (__start0, __temp0, __end0);
-    __action23(input, __temp0)
+    __action6(
+        input,
+        __0,
+        __1,
+        __2,
+        __3,
+        __temp0,
+        __5,
+        __6,
+        __7,
+    )
 }
 
 #[allow(unused_variables)]
-fn __action38<'input, 's>(
+fn __action35<
+    'input,
+    's,
+>(
     input: &'input str,
-    __lookbehind: &usize,
-    __lookahead: &usize,
-) -> Rc<[Tree]> {
-    let __start0 = __lookbehind.clone();
-    let __end0 = __lookahead.clone();
-    let __temp0 = __action30(input, &__start0, &__end0);
+    __0: (usize, &'input str, usize),
+    __1: (usize, &'input str, usize),
+    __2: (usize, &'input str, usize),
+    __3: (usize, alloc::vec::Vec<Tree>, usize),
+    __4: (usize, &'input str, usize),
+) -> Tree
+{
+    let __start0 = __1.2.clone();
+    let __end0 = __2.0.clone();
+    let __temp0 = __action23(
+        input,
+        &__start0,
+        &__end0,
+    );
     let __temp0 = (__start0, __temp0, __end0);
-    __action22(input, __temp0)
+    __action8(
+        input,
+        __0,
+        __1,
+        __temp0,
+        __2,
+        __3,
+        __4,
+    )
 }
 
 #[allow(unused_variables)]
-fn __action39<'input, 's>(
+fn __action36<
+    'input,
+    's,
+>(
     input: &'input str,
-    __0: (usize, alloc::vec::Vec<Tree>, usize),
-) -> Rc<[Tree]> {
-    let __start0 = __0.0.clone();
-    let __end0 = __0.2.clone();
-    let __temp0 = __action31(input, __0);
+    __0: (usize, &'input str, usize),
+    __1: (usize, &'input str, usize),
+    __2: (usize, alloc::vec::Vec<String>, usize),
+    __3: (usize, &'input str, usize),
+    __4: (usize, alloc::vec::Vec<Tree>, usize),
+    __5: (usize, &'input str, usize),
+) -> Tree
+{
+    let __start0 = __2.0.clone();
+    let __end0 = __2.2.clone();
+    let __temp0 = __action24(
+        input,
+        __2,
+    );
     let __temp0 = (__start0, __temp0, __end0);
-    __action22(input, __temp0)
+    __action8(
+        input,
+        __0,
+        __1,
+        __temp0,
+        __3,
+        __4,
+        __5,
+    )
 }
 
-pub trait __ToTriple<'input, 's> {
-    fn to_triple(
-        value: Self,
-    ) -> Result<
-        (usize, Token<'input>, usize),
-        __lalrpop_util::ParseError<usize, Token<'input>, &'static str>,
-    >;
+pub trait __ToTriple<'input, 's, > {
+    fn to_triple(value: Self) -> Result<(usize,Token<'input>,usize), __lalrpop_util::ParseError<usize, Token<'input>, &'static str>>;
 }
 
-impl<'input, 's> __ToTriple<'input, 's> for (usize, Token<'input>, usize) {
-    fn to_triple(
-        value: Self,
-    ) -> Result<
-        (usize, Token<'input>, usize),
-        __lalrpop_util::ParseError<usize, Token<'input>, &'static str>,
-    > {
+impl<'input, 's, > __ToTriple<'input, 's, > for (usize, Token<'input>, usize) {
+    fn to_triple(value: Self) -> Result<(usize,Token<'input>,usize), __lalrpop_util::ParseError<usize, Token<'input>, &'static str>> {
         Ok(value)
     }
 }
-impl<'input, 's> __ToTriple<'input, 's> for Result<(usize, Token<'input>, usize), &'static str> {
-    fn to_triple(
-        value: Self,
-    ) -> Result<
-        (usize, Token<'input>, usize),
-        __lalrpop_util::ParseError<usize, Token<'input>, &'static str>,
-    > {
+impl<'input, 's, > __ToTriple<'input, 's, > for Result<(usize, Token<'input>, usize), &'static str> {
+    fn to_triple(value: Self) -> Result<(usize,Token<'input>,usize), __lalrpop_util::ParseError<usize, Token<'input>, &'static str>> {
         match value {
             Ok(v) => Ok(v),
             Err(error) => Err(__lalrpop_util::ParseError::User { error }),
diff --git a/src/main.rs b/src/main.rs
index 1f83267..f7ec21c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -4,7 +4,9 @@
 #![feature(crate_visibility_modifier)]
 #![feature(let_else)]
 
+use std::cell::RefCell;
 use std::io;
+use std::rc::Rc;
 
 use rustyline::validate::{
     MatchingBracketValidator, ValidationContext, ValidationResult, Validator,
@@ -33,9 +35,9 @@ fn main() {
 fn run_file(file: &str) -> io::Result<()> {
     let src = std::fs::read_to_string(file)?;
     let tree = grammar::FileParser::new().parse(&src).unwrap();
-    let mut env = eval::default_env();
+    let env = Rc::new(RefCell::new(eval::default_env()));
     for i in tree {
-        eval::eval(&i, &mut env).unwrap();
+        eval::eval(&i, Rc::clone(&env)).unwrap();
     }
     Ok(())
 }
@@ -46,14 +48,23 @@ fn repl() {
         brackets: MatchingBracketValidator::new(),
     }));
 
-    let mut env = eval::default_env();
+    let env = Rc::new(RefCell::new(eval::default_env()));
 
     while let Ok(line) = rl.readline("> ") {
         rl.add_history_entry(&line);
 
         let tree = grammar::TreeParser::new().parse(&line).unwrap();
         // dbg!(&tree);
-        println!("< {:?}", eval::eval(&tree, &mut env))
+        match eval::eval(&tree, Rc::clone(&env)) {
+            Ok(v) => {
+                // Cant use == because it will panic. This is the only
+                // valid comparison to trap
+                if !matches!(v, value::Value::Trap) {
+                    println!("{}", v)
+                }
+            }
+            Err(e) => println!("! {}", e.0),
+        }
     }
 }
 
diff --git a/src/prims.rs b/src/prims.rs
index 62e67ff..45c1232 100644
--- a/src/prims.rs
+++ b/src/prims.rs
@@ -1,9 +1,12 @@
 use crate::eval::{err, RTError};
 use crate::value::Value;
 
-crate type Func = fn(&[Value]) -> Result<Value, RTError>;
 
-crate fn prims() -> &'static [(&'static str, Func)] {
+type Result = std::result::Result<Value, RTError>;
+
+crate type NativeFunc = for<'a> fn(&'a [Value]) -> Result;
+
+crate fn prims() -> &'static [(&'static str, NativeFunc)] {
     &[
         ("*", mul),
         ("+", add),
@@ -21,25 +24,27 @@ crate fn prims() -> &'static [(&'static str, Func)] {
         (">", gt),
         ("<=", le),
         (">=", ge),
+
+        ("_Z_debug", z_debug)
     ]
 }
 
 // TODO: DRY +-/*
-fn add(args: &[Value]) -> Result<Value, RTError> {
+fn add(args: &[Value]) -> Result {
     args.iter()
         .map(Value::as_num)
         .try_fold(0.0, |a, b| Ok(a + b?))
         .map(Value::Num)
 }
 
-fn mul(args: &[Value]) -> Result<Value, RTError> {
+fn mul(args: &[Value]) -> Result {
     args.iter()
         .map(Value::as_num)
         .try_fold(1.0, |a, b| Ok(a * b?))
         .map(Value::Num)
 }
 
-fn div(args: &[Value]) -> Result<Value, RTError> {
+fn div(args: &[Value]) -> Result {
     let init = args
         .get(0)
         .ok_or_else(|| RTError("`div` needs at least one argument".to_owned()))?
@@ -53,7 +58,7 @@ fn div(args: &[Value]) -> Result<Value, RTError> {
     }))
 }
 
-fn sub(args: &[Value]) -> Result<Value, RTError> {
+fn sub(args: &[Value]) -> Result {
     let init = args
         .get(0)
         .ok_or_else(|| RTError("`sub` needs at least one argument".to_owned()))?
@@ -67,17 +72,17 @@ fn sub(args: &[Value]) -> Result<Value, RTError> {
     }))
 }
 
-fn equals(args: &[Value]) -> Result<Value, RTError> {
+fn equals(args: &[Value]) -> Result {
     Ok(Value::Bool(args.array_windows().all(|[l, r]| l == r)))
 }
 
-fn display(args: &[Value]) -> Result<Value, RTError> {
+fn display(args: &[Value]) -> Result {
     let [arg] = args else {return err("To many args to `display`".to_owned())};
-    print!("{:?}", arg);
+    print!("{}", arg);
     Ok(Value::Trap)
 }
 
-fn newline(args: &[Value]) -> Result<Value, RTError> {
+fn newline(args: &[Value]) -> Result {
     if !args.is_empty() {
         return err("Newline takes no args".to_owned());
     }
@@ -85,7 +90,7 @@ fn newline(args: &[Value]) -> Result<Value, RTError> {
     Ok(Value::Trap)
 }
 
-fn abs(args: &[Value]) -> Result<Value, RTError> {
+fn abs(args: &[Value]) -> Result {
     let [v] = args else { return err("abs takes 1 arg".to_owned()) };
     let ans = v.as_num()?.abs();
     Ok(Value::Num(ans))
@@ -95,7 +100,7 @@ crate fn compare_core(
     args: &[Value],
     f: fn(f64, f64) -> bool,
     name: &'static str,
-) -> Result<Value, RTError> {
+) -> Result {
     for [l, r] in args.array_windows() {
         let (Value::Num(l), Value::Num(r)) = (l,r) else 
         { 
@@ -114,11 +119,16 @@ crate fn compare_core(
 macro_rules! cmps {
     ($(($name:ident $op:tt))*) => {
         $(
-            fn $name(args: &[Value]) -> Result<Value, RTError> {
+            fn $name(args: &[Value]) -> Result {
                 compare_core(args, |l, r| l $op r, stringify!($op))
             }
         )*
     };
 }
 
-cmps! { (lt <) (gt >) (le <=) (ge >=) }
\ No newline at end of file
+cmps! { (lt <) (gt >) (le <=) (ge >=) }
+
+fn z_debug(args: &[Value]) -> Result {
+    eprintln!("{:?}", args);
+    Ok(Value::Trap)
+}
\ No newline at end of file
diff --git a/src/snapshots/handball__tests__run-pass@4-1-6-Assignments.scm.snap b/src/snapshots/handball__tests__run-pass@4-1-6-Assignments.scm.snap
new file mode 100644
index 0000000..d8a09b3
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@4-1-6-Assignments.scm.snap
@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass r7rs-spec\\4-1-6-Assignments.scm"
+
+---
+3.05.0
diff --git a/src/snapshots/handball__tests__run-pass@ambig-scope.scm.snap b/src/snapshots/handball__tests__run-pass@ambig-scope.scm.snap
new file mode 100644
index 0000000..657c8a2
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@ambig-scope.scm.snap
@@ -0,0 +1,13 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: run-pass ambig-scope.scm
+
+---
+
+42.0
+1.0
+2.0
+3.0
+2.0
+1.0
diff --git a/src/snapshots/handball__tests__run-pass@assign-closures.scm.snap b/src/snapshots/handball__tests__run-pass@assign-closures.scm.snap
new file mode 100644
index 0000000..4aa09ff
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@assign-closures.scm.snap
@@ -0,0 +1,11 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\assign-closures.scm"
+
+---
+1.0
+2.0
+2.0
+3.0
+
diff --git a/src/snapshots/handball__tests__run-pass@assign-shadowed-later.scm.snap b/src/snapshots/handball__tests__run-pass@assign-shadowed-later.scm.snap
new file mode 100644
index 0000000..a1e7c91
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@assign-shadowed-later.scm.snap
@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\assign-shadowed-later.scm"
+
+---
+1.0
+0.0
+
diff --git a/src/snapshots/handball__tests__run-pass@bagel-donut.scm.snap b/src/snapshots/handball__tests__run-pass@bagel-donut.scm.snap
new file mode 100644
index 0000000..93d1fbe
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@bagel-donut.scm.snap
@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\bagel-donut.scm"
+
+---
+4.0
+2.0
+
diff --git a/src/snapshots/handball__tests__run-pass@capture.scm.snap b/src/snapshots/handball__tests__run-pass@capture.scm.snap
new file mode 100644
index 0000000..4d73305
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@capture.scm.snap
@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: run-pass capture.scm
+
+---
+#<procedure>
+2.0
+
diff --git a/src/snapshots/handball__tests__run-pass@close-over-function-param.scm.snap b/src/snapshots/handball__tests__run-pass@close-over-function-param.scm.snap
new file mode 100644
index 0000000..050e695
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@close-over-function-param.scm.snap
@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\close-over-function-param.scm"
+
+---
+77.0
diff --git a/src/snapshots/handball__tests__run-pass@close-over-later-variable.scm.snap b/src/snapshots/handball__tests__run-pass@close-over-later-variable.scm.snap
new file mode 100644
index 0000000..49ff729
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@close-over-later-variable.scm.snap
@@ -0,0 +1,8 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\close-over-later-variable.scm"
+
+---
+2.0
+1.0
diff --git a/src/snapshots/handball__tests__run-pass@close-unused.scm.snap b/src/snapshots/handball__tests__run-pass@close-unused.scm.snap
new file mode 100644
index 0000000..8c5eeb6
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@close-unused.scm.snap
@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\close-unused.scm"
+
+---
+7.0
diff --git a/src/snapshots/handball__tests__run-pass@closed-closure-in-function.scm.snap b/src/snapshots/handball__tests__run-pass@closed-closure-in-function.scm.snap
new file mode 100644
index 0000000..9743e0c
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@closed-closure-in-function.scm.snap
@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\closed-closure-in-function.scm"
+
+---
+1.0
diff --git a/src/snapshots/handball__tests__run-pass@curry.scm.snap b/src/snapshots/handball__tests__run-pass@curry.scm.snap
new file mode 100644
index 0000000..7e245c0
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@curry.scm.snap
@@ -0,0 +1,8 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: run-pass curry.scm
+
+---
+3.0
+
diff --git a/src/snapshots/handball__tests__run-pass@gnarly-i.scm.snap b/src/snapshots/handball__tests__run-pass@gnarly-i.scm.snap
new file mode 100644
index 0000000..1b7b569
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@gnarly-i.scm.snap
@@ -0,0 +1,10 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\gnarly-i.scm"
+
+---
+3.0
+2.0
+1.0
+
diff --git a/src/snapshots/handball__tests__run-pass@mutate-levels.scm.snap b/src/snapshots/handball__tests__run-pass@mutate-levels.scm.snap
new file mode 100644
index 0000000..6853d0e
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@mutate-levels.scm.snap
@@ -0,0 +1,13 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\mutate-levels.scm"
+
+---
+2.0
+3.0
+3.0
+3.0
+7.0
+8.0
+
diff --git a/src/snapshots/handball__tests__run-pass@nested-assign.scm.snap b/src/snapshots/handball__tests__run-pass@nested-assign.scm.snap
new file mode 100644
index 0000000..744868e
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@nested-assign.scm.snap
@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\nested-assign.scm"
+
+---
+1.0
diff --git a/src/snapshots/handball__tests__run-pass@nested-closure.scm.snap b/src/snapshots/handball__tests__run-pass@nested-closure.scm.snap
new file mode 100644
index 0000000..744940e
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@nested-closure.scm.snap
@@ -0,0 +1,10 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\nested-closure.scm"
+
+---
+1.0
+2.0
+3.0
+
diff --git a/src/snapshots/handball__tests__run-pass@objects-are-a-poor-mans-closure.scm.snap b/src/snapshots/handball__tests__run-pass@objects-are-a-poor-mans-closure.scm.snap
new file mode 100644
index 0000000..e290ade
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@objects-are-a-poor-mans-closure.scm.snap
@@ -0,0 +1,20 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\objects-are-a-poor-mans-closure.scm"
+
+---
+1.0
+7.0
+1.0
+7.0
+
+8.0
+2.0
+8.0
+2.0
+
+9.0
+9.0
+
+
diff --git a/src/snapshots/handball__tests__run-pass@open-closure-in-function.scm.snap b/src/snapshots/handball__tests__run-pass@open-closure-in-function.scm.snap
new file mode 100644
index 0000000..6c929d9
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@open-closure-in-function.scm.snap
@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\open-closure-in-function.scm"
+
+---
+1.0
diff --git a/src/snapshots/handball__tests__run-pass@reference-closure-multiple-times.scm.snap b/src/snapshots/handball__tests__run-pass@reference-closure-multiple-times.scm.snap
new file mode 100644
index 0000000..a7095a5
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@reference-closure-multiple-times.scm.snap
@@ -0,0 +1,8 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\reference-closure-multiple-times.scm"
+
+---
+1.0
+1.0
diff --git a/src/snapshots/handball__tests__run-pass@reuse-closure-slot.scm.snap b/src/snapshots/handball__tests__run-pass@reuse-closure-slot.scm.snap
new file mode 100644
index 0000000..f3b7b5a
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@reuse-closure-slot.scm.snap
@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\reuse-closure-slot.scm"
+
+---
+1.0
diff --git a/src/snapshots/handball__tests__run-pass@scope.scm.snap b/src/snapshots/handball__tests__run-pass@scope.scm.snap
new file mode 100644
index 0000000..2474233
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@scope.scm.snap
@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\scope.scm"
+
+---
+7.0
+2.0
+
diff --git a/src/snapshots/handball__tests__run-pass@shadow-closure-with-local.scm.snap b/src/snapshots/handball__tests__run-pass@shadow-closure-with-local.scm.snap
new file mode 100644
index 0000000..7ed2745
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@shadow-closure-with-local.scm.snap
@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\shadow-closure-with-local.scm"
+
+---
+0.0
+1.0
+
diff --git a/src/snapshots/handball__tests__run-pass@unused-later-closures.scm.snap b/src/snapshots/handball__tests__run-pass@unused-later-closures.scm.snap
new file mode 100644
index 0000000..82b2efb
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@unused-later-closures.scm.snap
@@ -0,0 +1,8 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\unused-later-closures.scm"
+
+---
+1.0
+1.0
diff --git a/src/snapshots/handball__tests__run-pass@use-after-close.scm.snap b/src/snapshots/handball__tests__run-pass@use-after-close.scm.snap
new file mode 100644
index 0000000..5641625
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@use-after-close.scm.snap
@@ -0,0 +1,7 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\use-after-close.scm"
+
+---
+1.0
diff --git a/src/snapshots/handball__tests__run-pass@val-or-var.scm.snap b/src/snapshots/handball__tests__run-pass@val-or-var.scm.snap
new file mode 100644
index 0000000..bb679ec
--- /dev/null
+++ b/src/snapshots/handball__tests__run-pass@val-or-var.scm.snap
@@ -0,0 +1,9 @@
+---
+source: src/tests.rs
+assertion_line: 41
+expression: "run-pass closure\\val-or-var.scm"
+
+---
+0.0
+1.0
+
diff --git a/src/test/run-pass/ambig-scope.scm b/src/test/run-pass/ambig-scope.scm
new file mode 100644
index 0000000..57a27ff
--- /dev/null
+++ b/src/test/run-pass/ambig-scope.scm
@@ -0,0 +1,22 @@
+#lang scheme
+
+(define (displayln x)
+  (newline)
+  (display x))
+
+(define (ambig1 x)
+  (lambda (x) x))
+
+(displayln ((ambig1 13) 42))
+
+(define (ambig2 a)
+  (displayln a)
+  (define a- a)
+  (lambda (b)
+    (displayln b)
+    (lambda (a)
+      (displayln a)
+      (displayln b)
+      (displayln a-))))
+
+(((ambig2 1) 2) 3)
diff --git a/src/test/run-pass/capture.scm b/src/test/run-pass/capture.scm
new file mode 100644
index 0000000..83898ef
--- /dev/null
+++ b/src/test/run-pass/capture.scm
@@ -0,0 +1,13 @@
+#lang scheme
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (const x)
+  (lambda () x))
+
+(define two-thunk (const 2))
+
+(displayln two-thunk)
+(displayln (two-thunk))
diff --git a/src/test/run-pass/closure/assign-closures.scm b/src/test/run-pass/closure/assign-closures.scm
new file mode 100644
index 0000000..69895e4
--- /dev/null
+++ b/src/test/run-pass/closure/assign-closures.scm
@@ -0,0 +1,28 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/assign_to_closure.lox
+
+(define f #f)
+(define g #f)
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+((lambda ()
+   (define local 1)
+
+   (define (f_)
+     (displayln local)
+     (set! local 2)
+     (displayln local))
+
+   (set! f f_)
+
+   (define (g_)
+     (displayln local)
+     (set! local 3)
+     (displayln local))
+
+   (set! g g_)))
+
+(f)
+(g)
diff --git a/src/test/run-pass/closure/assign-shadowed-later.scm b/src/test/run-pass/closure/assign-shadowed-later.scm
new file mode 100644
index 0000000..5a4275c
--- /dev/null
+++ b/src/test/run-pass/closure/assign-shadowed-later.scm
@@ -0,0 +1,17 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/assign_to_shadowed_later.lox
+
+(define a 0)
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+((lambda ()
+   (define (assign)
+     (set! a 1))
+
+   (define a 2)
+   (assign)
+   (displayln a)))
+
+(displayln a)
diff --git a/src/test/run-pass/closure/bagel-donut.scm b/src/test/run-pass/closure/bagel-donut.scm
new file mode 100644
index 0000000..ac06159
--- /dev/null
+++ b/src/test/run-pass/closure/bagel-donut.scm
@@ -0,0 +1,14 @@
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (make-print x)
+  (define (print)
+    (displayln x))
+  print)
+
+(define print-2 (make-print 2))
+(define print-4 (make-print 4))
+
+(print-4)
+(print-2)
diff --git a/src/test/run-pass/closure/close-over-function-param.scm b/src/test/run-pass/closure/close-over-function-param.scm
new file mode 100644
index 0000000..df024aa
--- /dev/null
+++ b/src/test/run-pass/closure/close-over-function-param.scm
@@ -0,0 +1,10 @@
+(define f #f)
+
+(define (foo param)
+  (define (f_)
+    (display param))
+  (set! f f_))
+
+(foo 77)
+
+(f)
diff --git a/src/test/run-pass/closure/close-over-later-variable.scm b/src/test/run-pass/closure/close-over-later-variable.scm
new file mode 100644
index 0000000..9a1a978
--- /dev/null
+++ b/src/test/run-pass/closure/close-over-later-variable.scm
@@ -0,0 +1,14 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/close_over_later_variable.lox
+
+(define (f)
+  (define a 1)
+  (define b 2)
+
+  (define (g)
+    (display b)
+    (newline)
+    (display a))
+
+  (g))
+
+(f)
diff --git a/src/test/run-pass/closure/close-unused.scm b/src/test/run-pass/closure/close-unused.scm
new file mode 100644
index 0000000..ab70eb0
--- /dev/null
+++ b/src/test/run-pass/closure/close-unused.scm
@@ -0,0 +1,6 @@
+((lambda ()
+   (define a 1)
+
+   (if #f (lambda () a) 0)))
+
+(display 7)
diff --git a/src/test/run-pass/closure/closed-closure-in-function.scm b/src/test/run-pass/closure/closed-closure-in-function.scm
new file mode 100644
index 0000000..11d8dd0
--- /dev/null
+++ b/src/test/run-pass/closure/closed-closure-in-function.scm
@@ -0,0 +1,11 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/closed_closure_in_function.lox
+
+(define f #f)
+
+((lambda ()
+   (define local 1)
+   (define (f_)
+     (display local))
+   (set! f f_)))
+
+(f)
diff --git a/src/test/run-pass/closure/gnarly-i.scm b/src/test/run-pass/closure/gnarly-i.scm
new file mode 100644
index 0000000..6190093
--- /dev/null
+++ b/src/test/run-pass/closure/gnarly-i.scm
@@ -0,0 +1,22 @@
+#lang scheme
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (outer)
+  (define x 1)
+
+  (define (middle)
+    (define (inner)
+      (displayln x))
+    (displayln 2)
+    inner)
+
+  (displayln 3)
+
+  middle)
+
+(define mid (outer))
+(define in (mid))
+(in)
diff --git a/src/test/run-pass/closure/mutate-levels.scm b/src/test/run-pass/closure/mutate-levels.scm
new file mode 100644
index 0000000..61f7d3d
--- /dev/null
+++ b/src/test/run-pass/closure/mutate-levels.scm
@@ -0,0 +1,24 @@
+(define x 2)
+
+(define (show-x)
+  (display x)
+  (newline))
+
+(show-x)
+(set! x 3)
+(show-x)
+
+((lambda ()
+   (define x 7)
+   (show-x)
+   (set! x 8)
+   (show-x)))
+
+((lambda ()
+   (define (show-x)
+     (display x)
+     (newline))
+   (define x 7)
+   (show-x)
+   (set! x 8)
+   (show-x)))
diff --git a/src/test/run-pass/closure/nested-assign.scm b/src/test/run-pass/closure/nested-assign.scm
new file mode 100644
index 0000000..5bd5b1e
--- /dev/null
+++ b/src/test/run-pass/closure/nested-assign.scm
@@ -0,0 +1,8 @@
+(define (outer)
+  (define x 0)
+  (define (y)
+    (set! x 1))
+  (y)
+  (display x))
+
+(outer)
diff --git a/src/test/run-pass/closure/nested-closure.scm b/src/test/run-pass/closure/nested-closure.scm
new file mode 100644
index 0000000..9e84874
--- /dev/null
+++ b/src/test/run-pass/closure/nested-closure.scm
@@ -0,0 +1,26 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/nested_closure.lox
+#lang scheme
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define f #f)
+
+(define (f1)
+  (define a 1)
+  (define (f2)
+    (define b 2)
+    (define (f3)
+      (define c 3)
+      (define (f4)
+        (displayln a)
+        (displayln b)
+        (displayln c))
+      (set! f f4))
+    (f3))
+  (f2))
+
+(f1)
+
+(f)
diff --git a/src/test/run-pass/closure/objects-are-a-poor-mans-closure.scm b/src/test/run-pass/closure/objects-are-a-poor-mans-closure.scm
new file mode 100644
index 0000000..0a00e31
--- /dev/null
+++ b/src/test/run-pass/closure/objects-are-a-poor-mans-closure.scm
@@ -0,0 +1,43 @@
+#lang scheme
+
+(define get-x 1)
+(define get-y 2)
+(define do-print 3)
+(define add 4)
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (vector x y)
+  (define (add-to other)
+    (vector (+ x (other get-x)) (+ y (other get-y))))
+
+  (lambda (message)
+    (if (= message get-x)
+        x
+        (if (= message get-y)
+            y
+            (if (= message add)
+                add-to
+                (if (= message do-print)
+                    ((lambda ()
+                       (displayln x)
+                       (displayln y)
+                       (newline)))
+                    ((lambda ()
+                       (displayln -99)
+                       0))))))))
+
+(define v-1-7 (vector 1 7))
+(displayln (v-1-7 get-x))
+(displayln (v-1-7 get-y))
+(v-1-7 do-print)
+
+(define v-8-2 (vector 8 2))
+(displayln (v-8-2 get-x))
+(displayln (v-8-2 get-y))
+(v-8-2 do-print)
+
+(define v-9-9 ((v-8-2 add) v-1-7))
+(v-9-9 do-print)
diff --git a/src/test/run-pass/closure/open-closure-in-function.scm b/src/test/run-pass/closure/open-closure-in-function.scm
new file mode 100644
index 0000000..904424e
--- /dev/null
+++ b/src/test/run-pass/closure/open-closure-in-function.scm
@@ -0,0 +1,9 @@
+#lang scheme
+
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/open_closure_in_function.lox
+
+((lambda ()
+   (define local 1)
+   (define (f)
+     (display local))
+   (f)))
diff --git a/src/test/run-pass/closure/reference-closure-multiple-times.scm b/src/test/run-pass/closure/reference-closure-multiple-times.scm
new file mode 100644
index 0000000..71ce1d7
--- /dev/null
+++ b/src/test/run-pass/closure/reference-closure-multiple-times.scm
@@ -0,0 +1,14 @@
+#lang scheme
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/reference_closure_multiple_times.lox
+
+(define f #f)
+
+((lambda ()
+   (define a 1)
+   (define (f_)
+     (display a)
+     (newline)
+     (display a))
+   (set! f f_)))
+
+(f)
diff --git a/src/test/run-pass/closure/reuse-closure-slot.scm b/src/test/run-pass/closure/reuse-closure-slot.scm
new file mode 100644
index 0000000..d963162
--- /dev/null
+++ b/src/test/run-pass/closure/reuse-closure-slot.scm
@@ -0,0 +1,15 @@
+#lang scheme
+
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/reuse_closure_slot.lox
+
+((lambda ()
+   (define f #f)
+   ((lambda ()
+      (define a 1)
+      (define (f_)
+        (display a))
+      (set! f f_)))
+
+   ((lambda ()
+      (define b 2)
+      (f)))))
diff --git a/src/test/run-pass/closure/scope.scm b/src/test/run-pass/closure/scope.scm
new file mode 100644
index 0000000..7c636b8
--- /dev/null
+++ b/src/test/run-pass/closure/scope.scm
@@ -0,0 +1,13 @@
+(define x 2)
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (gy y)
+  x)
+(define (gx x)
+  x)
+
+(displayln (gx 7))
+(displayln (gy 7))
diff --git a/src/test/run-pass/closure/shadow-closure-with-local.scm b/src/test/run-pass/closure/shadow-closure-with-local.scm
new file mode 100644
index 0000000..2d19f4e
--- /dev/null
+++ b/src/test/run-pass/closure/shadow-closure-with-local.scm
@@ -0,0 +1,15 @@
+; https://github.com/munificent/craftinginterpreters/blob/master/test/closure/shadow_closure_with_local.lox
+; TODO: Forbid this https://discordapp.com/channels/571040468092321801/618895179343986688/925533402592079912
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+((lambda ()
+   (define foo 0)
+   (define (f)
+     ((lambda ()
+        (displayln foo)
+        (define foo 1)
+        (displayln foo))))
+   (f)))
diff --git a/src/test/run-pass/closure/unused-later-closures.scm b/src/test/run-pass/closure/unused-later-closures.scm
new file mode 100644
index 0000000..e556b15
--- /dev/null
+++ b/src/test/run-pass/closure/unused-later-closures.scm
@@ -0,0 +1,19 @@
+(define closure #f)
+
+((lambda ()
+   (define a 1)
+
+   ((lambda ()
+      (define b 2)
+
+      (define (get-a)
+        a)
+
+      (set! closure get-a)
+
+      (if #f (lambda () b) 0)))
+
+   (display (closure))))
+
+(newline)
+(display (closure))
diff --git a/src/test/run-pass/closure/use-after-close.scm b/src/test/run-pass/closure/use-after-close.scm
new file mode 100644
index 0000000..355c468
--- /dev/null
+++ b/src/test/run-pass/closure/use-after-close.scm
@@ -0,0 +1,8 @@
+(define (outer)
+  (define x 1)
+  (define (inner)
+    (display x))
+  inner)
+
+(define clousre (outer))
+(clousre)
diff --git a/src/test/run-pass/closure/val-or-var.scm b/src/test/run-pass/closure/val-or-var.scm
new file mode 100644
index 0000000..2404e4d
--- /dev/null
+++ b/src/test/run-pass/closure/val-or-var.scm
@@ -0,0 +1,19 @@
+(define globalSet #f)
+(define globalGet #f)
+
+(define (main)
+  (define a 0)
+
+  (define (set)
+    (set! a 1))
+  (define (get)
+    (display a)
+    (newline))
+
+  (set! globalSet set)
+  (set! globalGet get))
+
+(main)
+(globalGet)
+(globalSet)
+(globalGet)
diff --git a/src/test/run-pass/curry.scm b/src/test/run-pass/curry.scm
new file mode 100644
index 0000000..7fd510d
--- /dev/null
+++ b/src/test/run-pass/curry.scm
@@ -0,0 +1,10 @@
+#lang scheme
+
+(define (displayln x)
+  (display x)
+  (newline))
+
+(define (curry2 f)
+  (lambda (l) (lambda (r) (f l r))))
+
+(displayln (((curry2 +) 1) 2))
diff --git a/src/test/run-pass/fib.scm b/src/test/run-pass/fib.scm
index 92cbcab..6754aad 100644
--- a/src/test/run-pass/fib.scm
+++ b/src/test/run-pass/fib.scm
@@ -1,21 +1,28 @@
 #lang scheme
 
-(define (displayln x) (display x) (newline))
+(define (displayln x)
+  (display x)
+  (newline))
 
-(define (my-or a b) (if a #t b)) ; Test was written before we had `or`
+(define (my-or a b)
+  (if a #t b)) ; Test was written before we had `or`
 
-
-(define (fib-base? n) (my-or (= n 1) (= n 0)))
+(define (fib-base? n)
+  (my-or (= n 1) (= n 0)))
 
 (define (fib n)
-  (if (fib-base? n) 1
-      (+ (fib (- n 1)) (fib (- n 2)))))
-      
+  (if (fib-base? n) 1 (+ (fib (- n 1)) (fib (- n 2)))))
 
-(define (pfib n) (displayln n) (displayln (fib n)) (newline))
+(define (pfib n)
+  (displayln n)
+  (displayln (fib n))
+  (newline))
 
 (define (pfibs n)
-  (if (= n (- 1)) 0 ; Hack
-      ((lambda () (pfib n) (pfibs (- n 1)))))) ; Hack
+  (if (= n (- 1))
+      0 ; Hack
+      ((lambda ()
+         (pfib n)
+         (pfibs (- n 1)))))) ; Hack
 
-(pfibs 10)
\ No newline at end of file
+(pfibs 10)
diff --git a/src/test/run-pass/funcs.scm b/src/test/run-pass/funcs.scm
index 58c1e2d..856fd88 100644
--- a/src/test/run-pass/funcs.scm
+++ b/src/test/run-pass/funcs.scm
@@ -1,6 +1,8 @@
 #lang scheme
 
-(define (displayln x) (display x) (newline))
+(define (displayln x)
+  (display x)
+  (newline))
 
 (define add1 +)
 (displayln (add1 2 3))
@@ -8,5 +10,6 @@
 (define add2 (lambda (a b) (+ a b)))
 (displayln (add2 5 6))
 
-(define (add3 a b) (+ a b))
-(displayln (add3 5 9))
\ No newline at end of file
+(define (add3 a b)
+  (+ a b))
+(displayln (add3 5 9))
diff --git a/src/test/run-pass/lambda-calc.scm b/src/test/run-pass/lambda-calc.scm
index 5d3e56e..6da98f2 100644
--- a/src/test/run-pass/lambda-calc.scm
+++ b/src/test/run-pass/lambda-calc.scm
@@ -1,18 +1,24 @@
 #lang scheme
 
-(define (displayln x) (display x) (newline))
-(define (printbool x) (displayln (bool->int x)))
+(define (displayln x)
+  (display x)
+  (newline))
+(define (printbool x)
+  (displayln (bool->int x)))
 
-(define (true x y) x)
-(define (false x y) y)
-(define (and x y) (x y x))
-(define (or x y) (x x y))
-(define (not x) (x false true))
+(define (true x y)
+  x)
+(define (false x y)
+  y)
+(define (and x y)
+  (x y x))
+(define (or x y)
+  (x x y))
+(define (not x)
+  (x false true))
 
-(define (bool->int x) 
-  (if 
-   (equal? x true) 1 
-   (if (equal? x false) 0 (- 1))))
+(define (bool->int x)
+  (if (equal? x true) 1 (if (equal? x false) 0 (- 1))))
 
 (printbool true)
 (printbool false)
@@ -27,4 +33,4 @@
 (printbool (or true false))
 (printbool (or false true))
 (printbool (or false false))
-(printbool (and (or true false) (or false true)))
\ No newline at end of file
+(printbool (and (or true false) (or false true)))
diff --git a/src/test/run-pass/multi.scm b/src/test/run-pass/multi.scm
index 6df5bff..3a5dc57 100644
--- a/src/test/run-pass/multi.scm
+++ b/src/test/run-pass/multi.scm
@@ -1,5 +1,8 @@
 #lang scheme
 
-(define (multi) 1 2 3)
+(define (multi)
+  1
+  2
+  3)
 
-(display (multi))
\ No newline at end of file
+(display (multi))
diff --git a/src/test/run-pass/nested-defs.scm b/src/test/run-pass/nested-defs.scm
index 6d4265a..15c9eee 100644
--- a/src/test/run-pass/nested-defs.scm
+++ b/src/test/run-pass/nested-defs.scm
@@ -6,15 +6,14 @@
 (define (sqrt x)
   (define (sqrt-iter guess x)
     (define (good-enough? guess x)
-      (define (square x) (* x x))
+      (define (square x)
+        (* x x))
       (< (abs (- (square guess) x)) 0.001))
     (define (improve guess x)
-      (define (average x y) 
+      (define (average x y)
         (/ (+ x y) 2))
       (average guess (/ x guess)))
-    (if (good-enough? guess x)
-        guess
-        (sqrt-iter (improve guess x) x)))
+    (if (good-enough? guess x) guess (sqrt-iter (improve guess x) x)))
   (sqrt-iter 1.0 x))
 
-(display (sqrt 2))
\ No newline at end of file
+(display (sqrt 2))
diff --git a/src/test/run-pass/r7rs-spec/4-1-6-Assignments.scm b/src/test/run-pass/r7rs-spec/4-1-6-Assignments.scm
new file mode 100644
index 0000000..1ba7aca
--- /dev/null
+++ b/src/test/run-pass/r7rs-spec/4-1-6-Assignments.scm
@@ -0,0 +1,4 @@
+(define x 2)
+(display (+ x 1))
+(set! x 4)
+(display (+ x 1))
diff --git a/src/test/run-pass/sqrt.scm b/src/test/run-pass/sqrt.scm
index 051ac15..5300635 100644
--- a/src/test/run-pass/sqrt.scm
+++ b/src/test/run-pass/sqrt.scm
@@ -4,17 +4,16 @@
 ; http://sarabander.github.io/sicp/html/1_002e1.xhtml#g_t1_002e1_002e7
 
 (define (sqrt-iter guess x)
-  (if (good-enough? guess x)
-      guess
-      (sqrt-iter (improve guess x) x)))
+  (if (good-enough? guess x) guess (sqrt-iter (improve guess x) x)))
 
 (define (improve guess x)
   (average guess (/ x guess)))
 
-(define (average x y) 
+(define (average x y)
   (/ (+ x y) 2))
 
-(define (square x) (* x x))
+(define (square x)
+  (* x x))
 
 (define (good-enough? guess x)
   (< (abs (- (square guess) x)) 0.001))
@@ -22,4 +21,4 @@
 (define (sqrt x)
   (sqrt-iter 1.0 x))
 
-(display (sqrt 2))
\ No newline at end of file
+(display (sqrt 2))
diff --git a/src/tests.rs b/src/tests.rs
index 7aecb78..c69e945 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -18,7 +18,7 @@ upstream for this
 fn run_pass() {
     let manifest_dir = Path::new(env!("CARGO_MANIFEST_DIR"));
 
-    insta::glob!("test/run-pass/**.scm", |p| {
+    insta::glob!("test/run-pass/**/*.scm", |p| {
         let p = PathBuf::from(
             p.canonicalize()
                 .unwrap()
diff --git a/src/value.rs b/src/value.rs
index 09f309a..6ddf6de 100644
--- a/src/value.rs
+++ b/src/value.rs
@@ -1,16 +1,32 @@
-use crate::{ast, eval, prims};
+use crate::{eval, prims};
 use std::rc::Rc;
 
-#[derive(Clone)]
+#[derive(Clone /*, debug2::Debug*/)]
 crate enum Value {
     Num(f64),
-    Func(prims::Func),
-    Lambda(ast::Lambda),
+    // TODO: implement debug2::Debug for `fn` type, and do it right
+    // https://godbolt.org/z/vr9erGeKq
+    Func(prims::NativeFunc),
+    Lambda(eval::Lambda),
     Bool(bool),
     /// Result of things that shouldnt have values, like (define x 3)
+    /// TODO: Figure this out
     Trap,
 }
 
+impl std::fmt::Debug for Value {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Num(arg0) => f.debug_tuple("Num").field(arg0).finish(),
+            // We cant just pass the field because of livetime bs, see https://godbolt.org/z/vr9erGeKq
+            Self::Func(_) => f.debug_struct("Func").finish_non_exhaustive(),
+            Self::Lambda(arg0) => f.debug_tuple("Lambda").field(arg0).finish(),
+            Self::Bool(arg0) => f.debug_tuple("Bool").field(arg0).finish(),
+            Self::Trap => write!(f, "Trap"),
+        }
+    }
+}
+
 impl PartialEq for Value {
     fn eq(&self, other: &Self) -> bool {
         use Value::*;
@@ -18,7 +34,9 @@ impl PartialEq for Value {
             (Num(l), Num(r)) => l == r,
             (Func(l), Func(r)) => *l as usize == *r as usize,
             (Bool(l), Bool(r)) => l == r,
-            (Lambda(l), Lambda(r)) => Rc::ptr_eq(&l.0, &r.0) && Rc::ptr_eq(&l.1, &r.1),
+            (Lambda(l), Lambda(r)) => {
+                Rc::ptr_eq(&l.func, &r.func) && Rc::ptr_eq(&l.captures, &r.captures)
+            }
 
             (Num(_), _) => false,
             (Func(_), _) => false,
@@ -30,10 +48,10 @@ impl PartialEq for Value {
     }
 }
 
-impl std::fmt::Debug for Value {
+impl std::fmt::Display for Value {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            Self::Num(n) => n.fmt(f),
+            Self::Num(n) => std::fmt::Debug::fmt(n, f), // TODO: Change to displays
             Self::Func(_) => f.write_str("#<procedure>"),
             Self::Lambda(_) => f.write_str("#<procedure>"),
             Self::Bool(b) => f.write_str(if *b { "#t" } else { "#f" }),
@@ -51,14 +69,11 @@ impl Value {
         }
     }
 
-    crate fn as_func(&self) -> Result<eval::Callable, eval::RTError> {
+    crate fn as_func(self) -> Result<eval::Callable, eval::RTError> {
         match self {
-            Self::Func(f) => Ok(eval::Callable::Func(*f)),
+            Self::Func(f) => Ok(eval::Callable::Func(f)),
             Self::Lambda(l) => Ok(eval::Callable::Lambda(l)),
-            _ => Err(eval::RTError(format!(
-                "Expected a function, got {:?}",
-                self
-            ))),
+            _ => Err(eval::RTError(format!("Expected a function, got {}", self))),
         }
     }