diff --git a/mute-interpreter/src/env/core.rs b/mute-interpreter/src/env/core.rs
index 12ef3fd..cc96452 100644
--- a/mute-interpreter/src/env/core.rs
+++ b/mute-interpreter/src/env/core.rs
@@ -26,12 +26,11 @@ macro_rules! arithmetic {
 
 macro_rules! ordering {
     ($operator:tt) => {
-        NativeFunc(|args| {
+        NativeFunc(|mut args| {
             arg_count!(2, args.len());
 
-            let mut args = args.into_iter();
-            let lhs = args.next().unwrap();
-            let rhs = args.next().unwrap();
+            let lhs = args.pop_front().unwrap();
+            let rhs = args.pop_front().unwrap();
 
             let res = match (lhs, rhs) {
                 (Node::Int(lhs), Node::Int(rhs)) => lhs $operator rhs,
@@ -232,9 +231,8 @@ pub(super) fn core() -> HashMap<String, Value> {
         ),
         (
             "empty?",
-            NativeFunc(|args| {
+            NativeFunc(|mut args| {
                 arg_count!(1, args.len());
-                let mut args = args;
 
                 match args.pop_front().expect("argument length checked above") {
                     Node::List(list) => Node::Boolean(list.is_empty()),
@@ -249,9 +247,8 @@ pub(super) fn core() -> HashMap<String, Value> {
         ),
         (
             "count",
-            NativeFunc(|args| {
+            NativeFunc(|mut args| {
                 arg_count!(1, args.len());
-                let mut args = args;
 
                 match args.pop_front().expect("argument length checked above") {
                     Node::List(list) => Node::Int(list.len() as i64),
@@ -294,10 +291,10 @@ pub(super) fn core() -> HashMap<String, Value> {
         ),
         (
             "last",
-            NativeFunc(|args| {
+            NativeFunc(|mut args| {
                 arg_count!(1, args.len());
 
-                match args[0].borrow() {
+                match args.pop_front().expect("argument length checked above") {
                     Node::List(list) if list.is_empty() => Node::Nil,
                     Node::Vector(list) if list.is_empty() => Node::Nil,
 
@@ -312,10 +309,9 @@ pub(super) fn core() -> HashMap<String, Value> {
         ),
         (
             "nth",
-            NativeFunc(|args| {
+            NativeFunc(|mut args| {
                 arg_count!(2, args.len());
 
-                let mut args = args;
                 let list = match args.pop_front().expect("argument length checked above") {
                     Node::List(list) => list,
                     Node::Vector(vec) => vec.into(),
@@ -343,9 +339,8 @@ pub(super) fn core() -> HashMap<String, Value> {
         ),
         (
             "push-back",
-            NativeFunc(|args| {
-                let mut args = args;
-                match args.pop_front().expect("argument length checked above") {
+            NativeFunc(
+                |mut args| match args.pop_front().expect("argument length checked above") {
                     Node::List(mut list) => {
                         while let Some(val) = args.pop_front() {
                             list.push_back(val);
@@ -364,14 +359,13 @@ pub(super) fn core() -> HashMap<String, Value> {
                         "TypeError: expected list or vector, got {}.",
                         arg.get_type()
                     )),
-                }
-            }),
+                },
+            ),
         ),
         (
             "push-front",
-            NativeFunc(|args| {
-                let mut args = args;
-                match args.pop_front().expect("argument length checked above") {
+            NativeFunc(
+                |mut args| match args.pop_front().expect("argument length checked above") {
                     Node::List(mut list) => {
                         while let Some(val) = args.pop_back() {
                             list.push_front(val);
@@ -382,14 +376,13 @@ pub(super) fn core() -> HashMap<String, Value> {
                     arg => {
                         Node::Error(format!("TypeError: expected list, got {}.", arg.get_type()))
                     }
-                }
-            }),
+                },
+            ),
         ),
         (
             "pop-front",
-            NativeFunc(|args| {
-                let mut args = args;
-                match args.pop_front().expect("argument length checked above") {
+            NativeFunc(
+                |mut args| match args.pop_front().expect("argument length checked above") {
                     Node::List(mut list) => {
                         list.pop_front();
                         Node::List(list)
@@ -397,14 +390,13 @@ pub(super) fn core() -> HashMap<String, Value> {
                     arg => {
                         Node::Error(format!("TypeError: expected list, got {}.", arg.get_type()))
                     }
-                }
-            }),
+                },
+            ),
         ),
         (
             "pop-back",
-            NativeFunc(|args| {
-                let mut args = args;
-                match args.pop_front().expect("argument length checked above") {
+            NativeFunc(
+                |mut args| match args.pop_front().expect("argument length checked above") {
                     Node::List(mut list) => {
                         list.pop_back();
                         Node::List(list)
@@ -416,8 +408,8 @@ pub(super) fn core() -> HashMap<String, Value> {
                     arg => {
                         Node::Error(format!("TypeError: expected list, got {}.", arg.get_type()))
                     }
-                }
-            }),
+                },
+            ),
         ),
     ]
     .into_iter()
diff --git a/mute-interpreter/src/evaluator.rs b/mute-interpreter/src/evaluator.rs
index a8685cf..e44c698 100644
--- a/mute-interpreter/src/evaluator.rs
+++ b/mute-interpreter/src/evaluator.rs
@@ -3,10 +3,9 @@ use std::collections::VecDeque;
 use crate::{Environment, Error, Result};
 use mute_parser::Node;
 
-pub fn eval(env: &Environment, ast: VecDeque<Node>) -> Result<VecDeque<Node>> {
+pub fn eval(env: &Environment, mut ast: VecDeque<Node>) -> Result<VecDeque<Node>> {
     let mut results = VecDeque::new();
 
-    let mut ast = ast;
     while let Some(node) = ast.pop_front() {
         if let Node::List(list) = &node {
             let first = match list.front() {
@@ -17,8 +16,7 @@ pub fn eval(env: &Environment, ast: VecDeque<Node>) -> Result<VecDeque<Node>> {
                 node => node.cloned(),
             };
 
-            if let Some(Node::Macro(body)) = first {
-                let mut body = body;
+            if let Some(Node::Macro(mut body)) = first {
                 let parameters = body.pop_front().ok_or_else(|| todo!())?;
                 let parameters = read_parameters(parameters.clone())?;
                 let args = list.clone().into_iter().skip(1).collect::<VecDeque<Node>>();
@@ -56,8 +54,7 @@ pub fn eval_node(env: &Environment, ast_node: Node) -> Result<Node> {
             let operator = eval_node(env, list.pop_front().ok_or(Error::InvalidOperator)?)?;
 
             match operator {
-                Node::Function(body) => {
-                    let mut body = body;
+                Node::Function(mut body) => {
                     let parameters = body.pop_front().ok_or_else(|| todo!())?;
                     let parameters = read_parameters(parameters.clone())?;
 
@@ -81,8 +78,7 @@ pub fn eval_node(env: &Environment, ast_node: Node) -> Result<Node> {
                     }
                 }
 
-                Node::Macro(body) => {
-                    let mut body = body;
+                Node::Macro(mut body) => {
                     let parameters = body.pop_front().ok_or_else(|| todo!())?;
                     let parameters = read_parameters(parameters.clone())?;
 
@@ -135,8 +131,7 @@ pub fn eval_node(env: &Environment, ast_node: Node) -> Result<Node> {
 
             Node::Void
         }
-        Node::Let(body) => {
-            let mut body = body;
+        Node::Let(mut body) => {
             let args = match body.pop_front().ok_or_else(|| todo!())? {
                 Node::List(list) => list
                     .into_iter()
@@ -161,12 +156,11 @@ pub fn eval_node(env: &Environment, ast_node: Node) -> Result<Node> {
             eval(&env, body)?.pop_back().unwrap()
         }
 
-        Node::If(body) => {
+        Node::If(mut body) => {
             if body.len() != 2 && body.len() != 3 {
                 Err(Error::MismatchedArgCount(3, body.len()))?
             }
 
-            let mut body = body;
             let cond = body.pop_front().expect("arg count verified above").clone();
             let consequence = body.pop_front().expect("arg count verified above").clone();
             let alternative = match body.pop_front() {
@@ -222,8 +216,7 @@ pub fn eval_node(env: &Environment, ast_node: Node) -> Result<Node> {
             env,
             eval_node(env, body.pop_front().ok_or_else(|| todo!())?)?,
         )?,
-        Node::Apply(body) => {
-            let mut body = body;
+        Node::Apply(mut body) => {
             let operator = eval_node(env, body.pop_front().ok_or(Error::InvalidOperator)?)?;
 
             let mut args = match body.pop_front() {