diff --git a/flake.lock b/flake.lock
index bcf206d..e666a7d 100644
--- a/flake.lock
+++ b/flake.lock
@@ -2,11 +2,11 @@
   "nodes": {
     "nixpkgs": {
       "locked": {
-        "lastModified": 1736012469,
-        "narHash": "sha256-/qlNWm/IEVVH7GfgAIyP6EsVZI6zjAx1cV5zNyrs+rI=",
+        "lastModified": 1739020877,
+        "narHash": "sha256-mIvECo/NNdJJ/bXjNqIh8yeoSjVLAuDuTUzAo7dzs8Y=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "8f3e1f807051e32d8c95cd12b9b421623850a34d",
+        "rev": "a79cfe0ebd24952b580b1cf08cd906354996d547",
         "type": "github"
       },
       "original": {
diff --git a/src/environment.rs b/src/environment.rs
new file mode 100644
index 0000000..19e47fa
--- /dev/null
+++ b/src/environment.rs
@@ -0,0 +1,6 @@
+use std::{collections::HashMap, rc::Rc};
+
+use crate::node::NodeEnum;
+
+pub type EnvironmentInternalSymbolKey = u16;
+pub type Environment = HashMap<EnvironmentInternalSymbolKey, Rc<NodeEnum>>;
diff --git a/src/main.rs b/src/main.rs
index 193833e..6e3a82d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,18 +1,18 @@
-use node::{add::Add, constant::Constant, subtract::Subtract, Environment, Node, NodeEnum};
+use std::io::{self, stdout, BufRead, Write};
 
 mod node;
+mod environment;
 
 #[cfg(test)]
 mod tests;
 
 fn main() {
-    let mut env = Environment::new();
-    
-    let a = Constant::new(69.0).into();
-    let b = Constant::new(420.0).into();
-    let c = Constant::new(360.0).into();
-    let d: NodeEnum = Subtract::new(Add::new(a,b).into(), c).into();
-
-    println!("d_0: {}", d);
-    println!("d_1: {}", d.evaluate(&mut env).unwrap());
+    loop {
+        print!("> ");
+        let _ = stdout().flush();
+        
+        let mut line = String::new();
+        let stdin = io::stdin();
+        stdin.lock().read_line(&mut line).unwrap();
+    }
 }
diff --git a/src/node/add.rs b/src/node/add.rs
index 844ed6f..c16de87 100644
--- a/src/node/add.rs
+++ b/src/node/add.rs
@@ -1,34 +1,36 @@
-use super::{Node, NodeEnum, Precedence, constant::Constant};
+use std::rc::Rc;
 
-#[derive(Clone, Debug, PartialEq)]
+use super::{constant::Constant, Environment, Node, NodeEnum, Precedence};
+
+#[derive(Clone, Debug, PartialEq, PartialOrd)]
 pub struct Add {
-    left: Box<NodeEnum>,
-    right: Box<NodeEnum>,
+    left: Rc<NodeEnum>,
+    right: Rc<NodeEnum>,
 }
 
 impl Node for Add {
-    fn evaluate(&self, env: &mut super::Environment) -> Result<super::NodeEnum, String> {
+    fn evaluate(&self, env: &mut Environment) -> Result<Rc<NodeEnum>, String> {
         let evaluated_left = self.left.evaluate(env)?;
         let evaluated_right = self.right.evaluate(env)?;
 
-        match (evaluated_left, evaluated_right) {
+        match (evaluated_left.as_ref(), evaluated_right.as_ref()) {
             (NodeEnum::Constant(a), NodeEnum::Constant(b)) => {
-                Ok(Constant::new(a.get_value() + b.get_value()).into())
+                Ok(Rc::new(Constant::new(a.get_value() + b.get_value()).into()))
             }
             _ => Err(format!("Invalid Add operation: {:?}", self)),
         }
     }
 
-    fn to_string(&self) -> String {
+    fn as_string(&self, env: Option<&Environment>) -> String {
         let left_string = if self.left.precedence() <= self.precedence() {
-            format!("({})", self.left.to_string())
+            format!("({})", self.left.as_string(env))
         } else {
-            self.left.to_string()
+            self.left.as_string(env)
         };
         let right_string = if self.right.precedence() <= self.precedence() {
-            format!("({})", self.right.to_string())
+            format!("({})", self.right.as_string(env))
         } else {
-            self.right.to_string()
+            self.right.as_string(env)
         };
         format!("{}+{}", left_string, right_string)
     }
@@ -41,8 +43,8 @@ impl Node for Add {
 impl Add {
     pub fn new(left: NodeEnum, right: NodeEnum) -> Self {
         Self {
-            left: Box::new(left),
-            right: Box::new(right),
+            left: Rc::new(left),
+            right: Rc::new(right),
         }
     }
 }
diff --git a/src/node/assign.rs b/src/node/assign.rs
new file mode 100644
index 0000000..c73e24c
--- /dev/null
+++ b/src/node/assign.rs
@@ -0,0 +1,28 @@
+use std::rc::Rc;
+
+use super::{empty::Empty, symbol::Symbol, Environment, Node, NodeEnum, Precedence};
+
+#[derive(Debug, Clone, PartialEq, PartialOrd)]
+pub struct Assign {
+    left: Symbol,
+    right: Rc<NodeEnum>,
+}
+
+impl Node for Assign {
+    fn evaluate(&self, env: &mut Environment) -> Result<Rc<NodeEnum>, String> {
+        env.insert(self.left.get_value(), self.right.clone());
+        Ok(Empty::EMPTY.clone())
+    }
+
+    fn as_string(&self, env: Option<&Environment>) -> String {
+        format!(
+            "{} := {}",
+            self.left.as_string(env),
+            self.right.as_string(env)
+        )
+    }
+
+    fn precedence(&self) -> Precedence {
+        Precedence::Assign
+    }
+}
diff --git a/src/node/call.rs b/src/node/call.rs
new file mode 100644
index 0000000..16c9f02
--- /dev/null
+++ b/src/node/call.rs
@@ -0,0 +1,60 @@
+use std::rc::Rc;
+
+use crate::environment::Environment;
+
+use super::{Node, NodeEnum, Precedence, symbol::Symbol};
+
+#[derive(Debug, Clone, PartialEq, PartialOrd)]
+pub struct Call {
+    left: Rc<NodeEnum>,
+    right: Vec<Rc<NodeEnum>>,
+}
+
+impl Node for Call {
+    fn evaluate(&self, env: &mut Environment) -> Result<Rc<NodeEnum>, String> {
+        todo!();
+        let function = match self.left.as_ref() {
+            NodeEnum::Symbol(symbol) => match symbol.evaluate(env)?.as_ref() {
+                _ => {
+                    return Err(format!(
+                        "Cannot call {} as a function",
+                        symbol.as_string(Some(env))
+                    ));
+                }
+
+                NodeEnum::Function(function) => function,
+            },
+            NodeEnum::Function(function) => function,
+            NodeEnum::Call(call) => match call.evaluate(env)?.as_ref() {
+                NodeEnum::Function(function) => function,
+
+                // FIXME: This might fail for long chains of calls
+                _ => {
+                    return Err(format!(
+                        "Cannot call {} as a function",
+                        self.left.as_string(None)
+                    ));
+                }
+            },
+            _ => {
+                return Err(format!(
+                    "Cannot call {} as a function",
+                    self.left.as_string(None)
+                ));
+            }
+        };
+
+        // match function {
+        //
+        //     }
+        todo!()
+    }
+
+    fn as_string(&self, _: Option<&Environment>) -> String {
+        todo!()
+    }
+
+    fn precedence(&self) -> Precedence {
+        Precedence::Call
+    }
+}
diff --git a/src/node/constant.rs b/src/node/constant.rs
index f9d3465..c1dd79c 100644
--- a/src/node/constant.rs
+++ b/src/node/constant.rs
@@ -1,18 +1,18 @@
-use std::fmt::Display;
+use std::rc::Rc;
 
-use super::{Node, NodeEnum, Precedence};
+use super::{Environment, Node, Precedence};
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, PartialOrd)]
 pub struct Constant {
     value: f64,
 }
 
 impl Node for Constant {
-    fn evaluate(&self, _: &mut super::Environment) -> Result<super::NodeEnum, String> {
-        Ok(self.clone().into())
+    fn evaluate(&self, _: &mut super::Environment) -> Result<Rc<super::NodeEnum>, String> {
+        Ok(Rc::new(self.clone().into()))
     }
 
-    fn to_string(&self) -> String {
+    fn as_string(&self, _env: Option<&Environment>) -> String {
         self.value.to_string()
     }
 
diff --git a/src/node/divide.rs b/src/node/divide.rs
new file mode 100644
index 0000000..8be41f7
--- /dev/null
+++ b/src/node/divide.rs
@@ -0,0 +1,50 @@
+use std::rc::Rc;
+
+use super::{Node, NodeEnum, Precedence, constant::Constant};
+
+#[derive(Clone, Debug, PartialEq, PartialOrd)]
+pub struct Divide {
+    left: Rc<NodeEnum>,
+    right: Rc<NodeEnum>,
+}
+
+impl Node for Divide {
+    fn evaluate(&self, env: &mut super::Environment) -> Result<Rc<super::NodeEnum>, String> {
+        let evaluated_left = self.left.evaluate(env)?;
+        let evaluated_right = self.right.evaluate(env)?;
+
+        match (evaluated_left.as_ref(), evaluated_right.as_ref()) {
+            (NodeEnum::Constant(a), NodeEnum::Constant(b)) => {
+                Ok(Rc::new(Constant::new(a.get_value() / b.get_value()).into()))
+            }
+            _ => Err(format!("Invalid Divide operation: {:?}", self)),
+        }
+    }
+
+    fn as_string(&self, env: Option<&super::Environment>) -> String {
+        let left_string = if self.left.precedence() <= self.precedence() {
+            format!("({})", self.left.as_string(env))
+        } else {
+            self.left.as_string(env)
+        };
+        let right_string = if self.right.precedence() <= self.precedence() {
+            format!("({})", self.right.as_string(env))
+        } else {
+            self.right.as_string(env)
+        };
+        format!("{}/{}", left_string, right_string)
+    }
+
+    fn precedence(&self) -> Precedence {
+        Precedence::Factor
+    }
+}
+
+impl Divide {
+    pub fn new(left: NodeEnum, right: NodeEnum) -> Self {
+        Self {
+            left: Rc::new(left),
+            right: Rc::new(right),
+        }
+    }
+}
diff --git a/src/node/empty.rs b/src/node/empty.rs
new file mode 100644
index 0000000..a13607c
--- /dev/null
+++ b/src/node/empty.rs
@@ -0,0 +1,23 @@
+use std::{rc::Rc, sync::LazyLock};
+
+use super::{Environment, Node, NodeEnum, Precedence};
+
+#[derive(Debug, Clone, PartialEq, PartialOrd)]
+pub struct Empty;
+impl Node for Empty {
+    fn evaluate(&self, _: &mut Environment) -> Result<Rc<NodeEnum>, String> {
+        Ok(Empty::EMPTY.clone())
+    }
+
+    fn as_string(&self, _: Option<&Environment>) -> String {
+        String::from("{{#VOID}}")
+    }
+
+    fn precedence(&self) -> Precedence {
+        Precedence::Empty
+    }
+}
+
+impl Empty {
+    pub const EMPTY: LazyLock<Rc<NodeEnum>> = LazyLock::new(|| Rc::new(Empty{}.into()));
+}
diff --git a/src/node/function.rs b/src/node/function.rs
new file mode 100644
index 0000000..64d8bf4
--- /dev/null
+++ b/src/node/function.rs
@@ -0,0 +1,53 @@
+use std::rc::Rc;
+
+use crate::environment::Environment;
+
+use super::{Node, NodeEnum, Precedence, symbol::Symbol};
+
+#[derive(Debug, Clone, PartialEq, PartialOrd)]
+pub enum FunctionType {
+    Native(
+        &'static str,
+        fn(Vec<Rc<NodeEnum>>) -> Result<Rc<NodeEnum>, String>,
+    ),
+    UserFunction(Rc<NodeEnum>),
+}
+
+#[derive(Debug, Clone, PartialEq, PartialOrd)]
+pub struct Function {
+    function: FunctionType,
+    // TODO: Finish reasoning about whether or not this is
+    // the right way to implement functions
+    arguments: Vec<Symbol>,
+}
+
+impl Node for Function {
+    fn evaluate(&self, _: &mut Environment) -> Result<Rc<NodeEnum>, String> {
+        Ok(Rc::new(self.clone().into()))
+    }
+
+    fn as_string(&self, env: Option<&Environment>) -> String {
+        let args = self
+            .arguments
+            .iter()
+            .map(|x| Node::as_string(x, None))
+            .reduce(|acc, e| format!("{acc}, {e}"))
+            .unwrap_or("()".to_owned());
+
+        match &self.function {
+            FunctionType::Native(name, _) => name.to_owned().to_owned(),
+            FunctionType::UserFunction(body) => format!("({args} -> {})", body.as_string(env)),
+        }
+    }
+
+    fn precedence(&self) -> Precedence {
+        Precedence::Call
+    }
+}
+
+impl Function {
+    // TODO: Implement new.
+    // pub fn new(t: FunctionType, ) -> Self {
+    //
+    // }
+}
diff --git a/src/node/mod.rs b/src/node/mod.rs
index e6a46be..5df0df3 100644
--- a/src/node/mod.rs
+++ b/src/node/mod.rs
@@ -1,41 +1,71 @@
-use std::{cmp::Ordering, collections::HashMap, fmt::Display};
+use std::{collections::HashMap, fmt::Display, rc::Rc};
 
 use add::Add;
+use assign::Assign;
+use call::Call;
 use constant::Constant;
+use divide::Divide;
+use empty::Empty;
 use enum_dispatch::enum_dispatch;
+use function::Function;
+use multiply::Multiply;
+use node_ref::NodeRef;
 use subtract::Subtract;
+use symbol::Symbol;
+
+use crate::environment::Environment;
 
-pub mod constant;
 pub mod add;
+pub mod constant;
+pub mod divide;
+pub mod multiply;
 pub mod subtract;
+pub mod symbol;
+mod node_ref;
+mod assign;
+mod empty;
+mod function;
+mod call;
 
 #[enum_dispatch]
 #[enum_dispatch(Debug, Clone, PartialEq, PartialOrd, ToString)]
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone, PartialEq, PartialOrd)]
 pub enum NodeEnum {
-    Constant(Constant),
-    Add(Add),
-    Subtract(Subtract)
+    Constant,
+    Add,
+    Subtract,
+    Multiply,
+    Divide,
+    Symbol,
+    // NodeRef, // DEPRECATED, use Symbol
+    Assign,
+    Empty,
+    Function,
+    Call
 }
 
 #[derive(PartialEq, Eq, PartialOrd, Ord)]
 pub enum Precedence {
+    Empty,
+    Assign,
+    Compare,
+    Equality,
     Term,
     Factor,
+    Unary,
+    Call,
     Primary,
 }
 
-pub type Environment = HashMap<u16, NodeEnum>;
-
 #[enum_dispatch(NodeEnum)]
 pub trait Node {
-    fn evaluate(&self, _: &mut Environment) -> Result<NodeEnum, String>;
-    fn to_string(&self) -> String;
+    fn evaluate(&self, _: &mut Environment) -> Result<Rc<NodeEnum>, String>;
+    fn as_string(&self, _: Option<&Environment>) -> String;
     fn precedence(&self) -> Precedence;
 }
 
 impl Display for NodeEnum {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}", Node::to_string(self))
+        write!(f, "{}", Node::as_string(self, None))
     }
 }
diff --git a/src/node/multiply.rs b/src/node/multiply.rs
new file mode 100644
index 0000000..6304daf
--- /dev/null
+++ b/src/node/multiply.rs
@@ -0,0 +1,50 @@
+use std::rc::Rc;
+
+use super::{Node, NodeEnum, Precedence, constant::Constant};
+
+#[derive(Clone, Debug, PartialEq, PartialOrd)]
+pub struct Multiply {
+    left: Rc<NodeEnum>,
+    right: Rc<NodeEnum>,
+}
+
+impl Node for Multiply {
+    fn evaluate(&self, env: &mut super::Environment) -> Result<Rc<super::NodeEnum>, String> {
+        let evaluated_left = self.left.evaluate(env)?;
+        let evaluated_right = self.right.evaluate(env)?;
+
+        match (evaluated_left.as_ref(), evaluated_right.as_ref()) {
+            (NodeEnum::Constant(a), NodeEnum::Constant(b)) => {
+                Ok(Rc::new(Constant::new(a.get_value() * b.get_value()).into()))
+            }
+            _ => Err(format!("Invalid Multiply operation: {:?}", self)),
+        }
+    }
+
+    fn as_string(&self, env: Option<&super::Environment>) -> String {
+        let left_string = if self.left.precedence() <= self.precedence() {
+            format!("({})", self.left.as_string(env))
+        } else {
+            self.left.as_string(env)
+        };
+        let right_string = if self.right.precedence() <= self.precedence() {
+            format!("({})", self.right.as_string(env))
+        } else {
+            self.right.as_string(env)
+        };
+        format!("{}*{}", left_string, right_string)
+    }
+
+    fn precedence(&self) -> Precedence {
+        Precedence::Factor
+    }
+}
+
+impl Multiply {
+    pub fn new(left: NodeEnum, right: NodeEnum) -> Self {
+        Self {
+            left: Rc::new(left),
+            right: Rc::new(right),
+        }
+    }
+}
diff --git a/src/node/node_ref.rs b/src/node/node_ref.rs
new file mode 100644
index 0000000..2ab92e1
--- /dev/null
+++ b/src/node/node_ref.rs
@@ -0,0 +1,30 @@
+use std::rc::Rc;
+
+use super::{Environment, Node, NodeEnum, Precedence};
+
+#[derive(Debug, Clone, PartialEq, PartialOrd)]
+pub struct NodeRef {
+    value: Rc<NodeEnum>,
+}
+
+impl Node for NodeRef {
+    fn evaluate(&self, env: &mut Environment) -> Result<Rc<NodeEnum>, String> {
+        self.value.evaluate(env)
+    }
+
+    fn as_string(&self, env: Option<&Environment>) -> String {
+        self.value.as_string(env)
+    }
+
+    fn precedence(&self) -> Precedence {
+        self.value.precedence()
+    }
+}
+
+impl NodeRef {
+    pub fn new(value: &Rc<NodeEnum>) -> Self {
+        Self {
+            value: value.clone(),
+        }
+    }
+}
diff --git a/src/node/subtract.rs b/src/node/subtract.rs
index e4524b4..e5498b1 100644
--- a/src/node/subtract.rs
+++ b/src/node/subtract.rs
@@ -1,34 +1,36 @@
-use super::{Node, NodeEnum, Precedence, constant::Constant};
+use std::rc::Rc;
 
-#[derive(Clone, Debug, PartialEq)]
+use super::{constant::Constant, Environment, Node, NodeEnum, Precedence};
+
+#[derive(Clone, Debug, PartialEq, PartialOrd)]
 pub struct Subtract {
-    left: Box<NodeEnum>,
-    right: Box<NodeEnum>,
+    left: Rc<NodeEnum>,
+    right: Rc<NodeEnum>,
 }
 
 impl Node for Subtract {
-    fn evaluate(&self, env: &mut super::Environment) -> Result<super::NodeEnum, String> {
+    fn evaluate(&self, env: &mut super::Environment) -> Result<Rc<super::NodeEnum>, String> {
         let evaluated_left = self.left.evaluate(env)?;
         let evaluated_right = self.right.evaluate(env)?;
 
-        match (evaluated_left, evaluated_right) {
+        match (evaluated_left.as_ref(), evaluated_right.as_ref()) {
             (NodeEnum::Constant(a), NodeEnum::Constant(b)) => {
-                Ok(Constant::new(a.get_value() - b.get_value()).into())
+                Ok(Rc::new(Constant::new(a.get_value() - b.get_value()).into()))
             }
             _ => Err(format!("Invalid Add operation: {:?}", self)),
         }
     }
 
-    fn to_string(&self) -> String {
+    fn as_string(&self, env: Option<&Environment>) -> String {
         let left_string = if self.left.precedence() <= self.precedence() {
-            format!("({})", self.left.to_string())
+            format!("({})", self.left.as_string(env))
         } else {
-            self.left.to_string()
+            self.left.as_string(env)
         };
         let right_string = if self.right.precedence() <= self.precedence() {
-            format!("({})", self.right.to_string())
+            format!("({})", self.right.as_string(env))
         } else {
-            self.right.to_string()
+            self.right.as_string(env)
         };
         format!("{}-{}", left_string, right_string)
     }
@@ -41,8 +43,8 @@ impl Node for Subtract {
 impl Subtract {
     pub fn new(left: NodeEnum, right: NodeEnum) -> Self {
         Self {
-            left: Box::new(left),
-            right: Box::new(right),
+            left: Rc::new(left),
+            right: Rc::new(right),
         }
     }
 }
diff --git a/src/node/symbol.rs b/src/node/symbol.rs
new file mode 100644
index 0000000..b987569
--- /dev/null
+++ b/src/node/symbol.rs
@@ -0,0 +1,86 @@
+use std::{
+    collections::HashMap,
+    rc::Rc,
+    sync::{LazyLock, Mutex},
+};
+
+use super::{Environment, Node, NodeEnum, Precedence, node_ref::NodeRef};
+use crate::environment::EnvironmentInternalSymbolKey;
+
+#[derive(Debug, Clone, PartialEq, PartialOrd)]
+pub struct Symbol {
+    value: EnvironmentInternalSymbolKey,
+}
+
+impl Node for Symbol {
+    fn evaluate(&self, env: &mut Environment) -> Result<Rc<NodeEnum>, String> {
+        if let Some(value) = env.get(&self.value) {
+            // TODO: Detect cyclic references and make sure they get
+            // deleted at some point
+            Ok(value.clone())
+        } else {
+            Ok(Rc::new(self.clone().into()))
+        }
+    }
+
+    fn as_string(&self, env: Option<&Environment>) -> String {
+        if let Some(env) = env {
+            if let Some(value) = env.get(&self.value) {
+                value.as_string(Some(env))
+            } else {
+                Symbol::ID_TO_STR_MAP
+                    .lock()
+                    .unwrap()
+                    .get(&self.value)
+                    .unwrap_or(&format!("{{#SYMBOL {}}}", self.value))
+                    .clone()
+            }
+        } else {
+            Symbol::ID_TO_STR_MAP
+                .lock()
+                .unwrap()
+                .get(&self.value)
+                .unwrap_or(&format!("{{#SYMBOL {}}}", self.value))
+                .clone()
+        }
+    }
+
+    fn precedence(&self) -> Precedence {
+        Precedence::Primary
+    }
+}
+
+impl Symbol {
+    const STR_TO_ID_MAP: LazyLock<Mutex<HashMap<String, EnvironmentInternalSymbolKey>>> =
+        LazyLock::new(|| HashMap::new().into());
+    const ID_TO_STR_MAP: LazyLock<Mutex<HashMap<EnvironmentInternalSymbolKey, String>>> =
+        LazyLock::new(|| HashMap::new().into());
+
+    pub fn new(value: EnvironmentInternalSymbolKey) -> Self {
+        Self { value }
+    }
+
+    pub fn new_from_str(str: String) -> Self {
+        if let Some(value) = Symbol::STR_TO_ID_MAP.lock().unwrap().get(str.as_str()) {
+            Self::new(value.clone())
+        } else {
+            let id = Symbol::STR_TO_ID_MAP
+                .lock()
+                .unwrap()
+                .len()
+                .try_into()
+                .unwrap();
+            Symbol::STR_TO_ID_MAP
+                .lock()
+                .unwrap()
+                .insert(str.clone(), id);
+            Symbol::ID_TO_STR_MAP.lock().unwrap().insert(id, str);
+
+            Self::new(id)
+        }
+    }
+
+    pub fn get_value(&self) -> EnvironmentInternalSymbolKey {
+        self.value
+    }
+}
diff --git a/src/tests/mod.rs b/src/tests/mod.rs
index 0c981ff..9883234 100644
--- a/src/tests/mod.rs
+++ b/src/tests/mod.rs
@@ -1,7 +1,10 @@
 mod arithmetic {
-    use crate::node::{
-        Environment, Node, NodeEnum, add::Add, constant::Constant, subtract::Subtract,
-    };
+    use std::rc::Rc;
+
+    use crate::{environment, node::{
+        add::Add, constant::Constant, divide::Divide, multiply::Multiply, subtract::Subtract, Node, NodeEnum
+    }};
+    use environment::Environment;
 
     use test_case::test_case;
 
@@ -17,7 +20,7 @@ mod arithmetic {
         let b = Constant::new(b).into();
         let d: NodeEnum = Add::new(a, b).into();
 
-        let value = d.evaluate(&mut env).unwrap();
+        let value = Rc::<NodeEnum>::try_unwrap(d.evaluate(&mut env).unwrap()).unwrap();
 
         assert!(
             value == Constant::new(e).into(),
@@ -40,7 +43,7 @@ mod arithmetic {
         let c = Constant::new(bb).into();
         let d: NodeEnum = Subtract::new(Add::new(a, b).into(), c).into();
 
-        let value = d.evaluate(&mut env).unwrap();
+        let value = Rc::<NodeEnum>::try_unwrap(d.evaluate(&mut env).unwrap()).unwrap();
 
         assert!(
             value == Constant::new(e).into(),
@@ -55,28 +58,72 @@ mod arithmetic {
     #[test_case(5.0, -10.0, -50.0 ; "when right is negative")]
     #[test_case(-5.0, -10.0, 50.0 ; "when both are negative")]
     #[test_case(2734589235234.23, 0.0, 0.0 ; "when 0 is involved")]
-    fn multiplication(a: f64, b: f64, e: f64) {}
+    fn multiplication(a: f64, b: f64, e: f64) {
+        let mut env = Environment::new();
+
+        let a = Constant::new(a).into();
+        let b = Constant::new(b).into();
+        let d: NodeEnum = Multiply::new(a, b).into();
+
+        let value = Rc::<NodeEnum>::try_unwrap(d.evaluate(&mut env).unwrap()).unwrap();
+
+        assert!(
+            value == Constant::new(e).into(),
+            "Expected {} got {}",
+            e,
+            value
+        )
+    }
 
     #[test_case(5.0, 10.0, 0.5 ; "when both are positive")]
     #[test_case(-5.0, 10.0, -0.5 ; "when left is negative")]
     #[test_case(5.0, -10.0, -0.5 ; "when right is negative")]
     #[test_case(-5.0, -10.0, 0.5 ; "when both are negative")]
-    fn division(a: f64, b: f64, e: f64) {}
+    fn division(a: f64, b: f64, e: f64) {
+        let mut env = Environment::new();
+
+        let a = Constant::new(a).into();
+        let b = Constant::new(b).into();
+        let d: NodeEnum = Divide::new(a, b).into();
+
+        let value = Rc::<NodeEnum>::try_unwrap(d.evaluate(&mut env).unwrap()).unwrap();
+
+        assert!(
+            value == Constant::new(e).into(),
+            "Expected {} got {}",
+            e,
+            value
+        )
+    }
+}
+
+mod functions {
+    #[test]
+    fn stringification() {
+        // let f = Function
+    }
 }
 
 mod expected_errors {
     use test_case::test_case;
 
     #[test_case(5.0, 0.0 ; "divide by zero")]
-    fn division(a: f64, b: f64) {}
+    fn division(a: f64, b: f64) {
+        let _ = a+b;
+    }
 }
 
 mod misc {
-    use crate::node::{
-        Environment, Node, NodeEnum, add::Add, constant::Constant, subtract::Subtract,
-    };
+    use test_case::test_case;
 
-    #[test_case(30, '+', 60, '-', 20, "(30+60)-20", "add and subtract")]
-    fn convert_to_string(a: into<f64>, op1: char, b: Into<f64>, op2: char, c: Into<f64>, e: String) {
+    #[test_case(30, '+', 60, '-', 20, "(30+60)-20" ; "add and subtract")]
+    fn convert_to_string(
+        a: impl Into<f64>,
+        op1: char,
+        b: impl Into<f64>,
+        op2: char,
+        c: impl Into<f64>,
+        e: &'static str,
+    ) {
     }
 }