diff --git a/src/env.rs b/src/env.rs
index 10ac386..53ae9d1 100644
--- a/src/env.rs
+++ b/src/env.rs
@@ -1,60 +1,6 @@
 use std::{borrow::Borrow, collections::HashMap, rc::Rc};
 
-use anyhow::Result;
-
-use crate::eval::Error;
-
-#[derive(Debug, PartialEq)]
-pub enum Expression {
-    // Values
-    Int(i64),
-    Boolean(bool),
-    Keyword(String),
-    String(String),
-    Nil,
-
-    // Collections
-    Vector(Vec<Rc<Expression>>),
-    HashMap(HashMap<String, Rc<Expression>>),
-
-    NativeFunc {
-        func: fn(args: Vec<Rc<Expression>>) -> Result<Rc<Expression>>,
-    },
-}
-
-impl std::fmt::Display for Expression {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            Expression::Int(val) => write!(f, "{}", val),
-            Expression::Boolean(true) => write!(f, "true"),
-            Expression::Boolean(false) => write!(f, "false"),
-            Expression::Keyword(val) => write!(f, ":{}", val),
-            Expression::String(val) => write!(f, "{}", val),
-            Expression::Nil => write!(f, "nil"),
-
-            Expression::Vector(vec) => {
-                let s = vec
-                    .iter()
-                    .map(|elem| elem.to_string())
-                    .reduce(|lhs, rhs| format!("{lhs} {rhs}"))
-                    .unwrap_or_default();
-
-                write!(f, "[{s}]")
-            }
-            Expression::HashMap(map) => {
-                let res = map
-                    .into_iter()
-                    .map(|(k, v)| format!("{k}: {v}"))
-                    .reduce(|lhs, rhs| format!("{lhs}, {rhs}"))
-                    .unwrap_or_default();
-
-                write!(f, "{{{res}}}")
-            }
-
-            Expression::NativeFunc { .. } => write!(f, "function"),
-        }
-    }
-}
+use crate::eval::{Error, Expression};
 
 pub type Environment = HashMap<String, Rc<Expression>>;
 
diff --git a/src/eval.rs b/src/eval.rs
index 2256572..04a53b7 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -1,12 +1,9 @@
-use std::{borrow::Borrow, rc::Rc};
+use std::{borrow::Borrow, collections::HashMap, rc::Rc};
 
 use anyhow::Result;
 use thiserror::Error;
 
-use crate::{
-    env::{Environment, Expression},
-    parser::Node,
-};
+use crate::{env::Environment, parser::Node};
 
 thread_local! {
     static TRUE: Rc<Expression> = Rc::new(Expression::Boolean(true));
@@ -14,6 +11,58 @@ thread_local! {
     static NIL: Rc<Expression> = Rc::new(Expression::Nil);
 }
 
+#[derive(Debug, PartialEq)]
+pub enum Expression {
+    // Values
+    Int(i64),
+    Boolean(bool),
+    Keyword(String),
+    String(String),
+    Nil,
+
+    // Collections
+    Vector(Vec<Rc<Expression>>),
+    HashMap(HashMap<String, Rc<Expression>>),
+
+    NativeFunc {
+        func: fn(args: Vec<Rc<Expression>>) -> Result<Rc<Expression>>,
+    },
+}
+
+impl std::fmt::Display for Expression {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Expression::Int(val) => write!(f, "{}", val),
+            Expression::Boolean(true) => write!(f, "true"),
+            Expression::Boolean(false) => write!(f, "false"),
+            Expression::Keyword(val) => write!(f, ":{}", val),
+            Expression::String(val) => write!(f, "{}", val),
+            Expression::Nil => write!(f, "nil"),
+
+            Expression::Vector(vec) => {
+                let s = vec
+                    .iter()
+                    .map(|elem| elem.to_string())
+                    .reduce(|lhs, rhs| format!("{lhs} {rhs}"))
+                    .unwrap_or_default();
+
+                write!(f, "[{s}]")
+            }
+            Expression::HashMap(map) => {
+                let res = map
+                    .into_iter()
+                    .map(|(k, v)| format!("{k}: {v}"))
+                    .reduce(|lhs, rhs| format!("{lhs}, {rhs}"))
+                    .unwrap_or_default();
+
+                write!(f, "{{{res}}}")
+            }
+
+            Expression::NativeFunc { .. } => write!(f, "function"),
+        }
+    }
+}
+
 #[derive(Debug, Error)]
 pub enum Error {
     #[error("could not find symbol in environment")]