diff --git a/README.md b/README.md
index d3b2464..c13dded 100644
--- a/README.md
+++ b/README.md
@@ -13,8 +13,8 @@ important than safety and ease of use.
 ### Effortless Concurrency
 
 Rust promises *fearless* concurrency, and Dust takes it a step further by making concurrency as
-simple as possible. Dust is organized into **statements**, and any sequence of statements can be
-run concurrently by simply adding the `async` keyword before the block of statements.
+*effortless* as possible. Dust is organized into **statements**, and any sequence of statements can
+be run concurrently by simply adding the `async` keyword before the block of statements.
 
 ```dust
 # This function will count from 0 to 9, sleeping for an increasing amount of
@@ -28,7 +28,7 @@ count_slowly = fn (
 		sleep_time = i * multiplier;
 
 		thread.sleep(sleep_time)
-		thread.write_line(i as str)
+		io.write_line(i as str)
 
 		i += 1
 	}
diff --git a/dust-lang/src/abstract_tree.rs b/dust-lang/src/abstract_tree.rs
index b20bd06..2718320 100644
--- a/dust-lang/src/abstract_tree.rs
+++ b/dust-lang/src/abstract_tree.rs
@@ -5,21 +5,21 @@ use std::{
 
 use serde::{Deserialize, Serialize};
 
-use crate::{Identifier, Type, Value};
+use crate::{Identifier, Span, Type, Value};
 
 #[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
-pub struct AbstractSyntaxTree<P> {
-    pub nodes: VecDeque<Node<P>>,
+pub struct AbstractSyntaxTree {
+    pub nodes: VecDeque<Node>,
 }
 
 #[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
-pub struct Node<P> {
-    pub statement: Statement<P>,
-    pub position: P,
+pub struct Node {
+    pub statement: Statement,
+    pub position: Span,
 }
 
-impl<P> Node<P> {
-    pub fn new(operation: Statement<P>, position: P) -> Self {
+impl Node {
+    pub fn new(operation: Statement, position: Span) -> Self {
         Self {
             statement: operation,
             position,
@@ -27,39 +27,39 @@ impl<P> Node<P> {
     }
 }
 
-impl<P> Display for Node<P> {
+impl Display for Node {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         write!(f, "{}", self.statement)
     }
 }
 
 #[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
-pub enum Statement<P> {
+pub enum Statement {
     // Top-level statements
-    Assign(Box<Node<P>>, Box<Node<P>>),
+    Assign(Box<Node>, Box<Node>),
 
     // Expressions
-    Add(Box<Node<P>>, Box<Node<P>>),
+    Add(Box<Node>, Box<Node>),
     BuiltInFunctionCall {
         function: BuiltInFunction,
-        type_arguments: Option<Vec<Node<P>>>,
-        value_arguments: Option<Vec<Node<P>>>,
+        type_arguments: Option<Vec<Node>>,
+        value_arguments: Option<Vec<Node>>,
     },
     FunctionCall {
-        function: Box<Node<P>>,
-        type_arguments: Option<Vec<Node<P>>>,
-        value_arguments: Option<Vec<Node<P>>>,
+        function: Box<Node>,
+        type_arguments: Option<Vec<Node>>,
+        value_arguments: Option<Vec<Node>>,
     },
-    PropertyAccess(Box<Node<P>>, Box<Node<P>>),
-    List(Vec<Node<P>>),
-    Multiply(Box<Node<P>>, Box<Node<P>>),
+    PropertyAccess(Box<Node>, Box<Node>),
+    List(Vec<Node>),
+    Multiply(Box<Node>, Box<Node>),
 
     // Hard-coded values
     Constant(Value),
     Identifier(Identifier),
 }
 
-impl<P> Statement<P> {
+impl Statement {
     pub fn expected_type(&self, variables: &HashMap<Identifier, Value>) -> Option<Type> {
         match self {
             Statement::Add(left, _) => left.statement.expected_type(variables),
@@ -77,7 +77,7 @@ impl<P> Statement<P> {
     }
 }
 
-impl<P> Display for Statement<P> {
+impl Display for Statement {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             Statement::Assign(left, right) => write!(f, "{left} = {right}"),
diff --git a/dust-lang/src/analyzer.rs b/dust-lang/src/analyzer.rs
index ec9485c..d42681c 100644
--- a/dust-lang/src/analyzer.rs
+++ b/dust-lang/src/analyzer.rs
@@ -7,7 +7,7 @@
 /// - `Analyzer` struct
 use std::collections::HashMap;
 
-use crate::{AbstractSyntaxTree, Identifier, Node, Statement, Type, Value};
+use crate::{AbstractSyntaxTree, Identifier, Node, Span, Statement, Type, Value};
 
 /// Analyzes the abstract syntax tree for errors.
 ///
@@ -22,10 +22,10 @@ use crate::{AbstractSyntaxTree, Identifier, Node, Statement, Type, Value};
 ///
 /// assert!(result.is_err());
 /// ```
-pub fn analyze<P: Clone>(
-    abstract_tree: &AbstractSyntaxTree<P>,
+pub fn analyze(
+    abstract_tree: &AbstractSyntaxTree,
     variables: &HashMap<Identifier, Value>,
-) -> Result<(), AnalyzerError<P>> {
+) -> Result<(), AnalyzerError> {
     let analyzer = Analyzer::new(abstract_tree, variables);
 
     analyzer.analyze()
@@ -44,14 +44,14 @@ pub fn analyze<P: Clone>(
 /// let result = analyzer.analyze();
 ///
 /// assert!(result.is_err());
-pub struct Analyzer<'a, P> {
-    abstract_tree: &'a AbstractSyntaxTree<P>,
+pub struct Analyzer<'a> {
+    abstract_tree: &'a AbstractSyntaxTree,
     variables: &'a HashMap<Identifier, Value>,
 }
 
-impl<'a, P: Clone> Analyzer<'a, P> {
+impl<'a> Analyzer<'a> {
     pub fn new(
-        abstract_tree: &'a AbstractSyntaxTree<P>,
+        abstract_tree: &'a AbstractSyntaxTree,
         variables: &'a HashMap<Identifier, Value>,
     ) -> Self {
         Self {
@@ -60,7 +60,7 @@ impl<'a, P: Clone> Analyzer<'a, P> {
         }
     }
 
-    pub fn analyze(&self) -> Result<(), AnalyzerError<P>> {
+    pub fn analyze(&self) -> Result<(), AnalyzerError> {
         for node in &self.abstract_tree.nodes {
             self.analyze_node(node)?;
         }
@@ -68,7 +68,7 @@ impl<'a, P: Clone> Analyzer<'a, P> {
         Ok(())
     }
 
-    fn analyze_node(&self, node: &Node<P>) -> Result<(), AnalyzerError<P>> {
+    fn analyze_node(&self, node: &Node) -> Result<(), AnalyzerError> {
         match &node.statement {
             Statement::Add(left, right) => {
                 if let Some(Type::Integer) | Some(Type::Float) =
@@ -166,11 +166,11 @@ impl<'a, P: Clone> Analyzer<'a, P> {
 }
 
 #[derive(Clone, Debug, PartialEq)]
-pub enum AnalyzerError<P> {
-    ExpectedFunction { position: P },
-    ExpectedIdentifier { actual: Node<P> },
-    ExpectedIntegerOrFloat { actual: Node<P> },
-    UnexpectedIdentifier { identifier: Node<P> },
+pub enum AnalyzerError {
+    ExpectedFunction { position: Span },
+    ExpectedIdentifier { actual: Node },
+    ExpectedIntegerOrFloat { actual: Node },
+    UnexpectedIdentifier { identifier: Node },
 }
 
 #[cfg(test)]
diff --git a/dust-lang/src/parse.rs b/dust-lang/src/parse.rs
index 026f523..d3f36af 100644
--- a/dust-lang/src/parse.rs
+++ b/dust-lang/src/parse.rs
@@ -39,7 +39,7 @@ use crate::{
 ///     }),
 /// );
 /// ```
-pub fn parse(input: &str) -> Result<AbstractSyntaxTree<Span>, ParseError> {
+pub fn parse(input: &str) -> Result<AbstractSyntaxTree, ParseError> {
     let lexer = Lexer::new(input);
     let mut parser = Parser::new(lexer);
     let mut nodes = VecDeque::new();
@@ -80,7 +80,7 @@ pub fn parse(input: &str) -> Result<AbstractSyntaxTree<Span>, ParseError> {
 ///
 /// assert_eq!(
 ///     nodes,
-///     Into::<VecDeque<Node<Span>>>::into([
+///     Into::<VecDeque<Node>>::into([
 ///         Node {
 ///             statement: Statement::Assign(
 ///                 Box::new(Node {
@@ -110,7 +110,7 @@ impl<'src> Parser<'src> {
         Parser { lexer, current }
     }
 
-    pub fn parse(&mut self) -> Result<Node<Span>, ParseError> {
+    pub fn parse(&mut self) -> Result<Node, ParseError> {
         self.parse_node(0)
     }
 
@@ -124,7 +124,7 @@ impl<'src> Parser<'src> {
         Ok(())
     }
 
-    fn parse_node(&mut self, precedence: u8) -> Result<Node<Span>, ParseError> {
+    fn parse_node(&mut self, precedence: u8) -> Result<Node, ParseError> {
         let left_node = self.parse_primary()?;
         let left_start = left_node.position.0;
 
@@ -181,7 +181,7 @@ impl<'src> Parser<'src> {
         Ok(left_node)
     }
 
-    fn parse_primary(&mut self) -> Result<Node<Span>, ParseError> {
+    fn parse_primary(&mut self) -> Result<Node, ParseError> {
         match self.current.clone() {
             (Token::Boolean(boolean), span) => {
                 self.next_token()?;
diff --git a/dust-lang/src/value.rs b/dust-lang/src/value.rs
index c0fdcde..fa1f609 100644
--- a/dust-lang/src/value.rs
+++ b/dust-lang/src/value.rs
@@ -12,7 +12,7 @@ use serde::{
     Deserialize, Deserializer, Serialize,
 };
 
-use crate::{identifier::Identifier, AbstractSyntaxTree, Type, Vm, VmError};
+use crate::{identifier::Identifier, AbstractSyntaxTree, Span, Type, Vm, VmError};
 
 #[derive(Clone, Debug, PartialEq)]
 pub struct Value(Arc<ValueInner>);
@@ -551,7 +551,7 @@ pub struct Function {
     pub name: Identifier,
     pub type_parameters: Option<Vec<Type>>,
     pub value_parameters: Option<Vec<(Identifier, Type)>>,
-    pub body: AbstractSyntaxTree<()>,
+    pub body: AbstractSyntaxTree,
 }
 
 impl Function {
@@ -560,7 +560,7 @@ impl Function {
         _type_arguments: Option<Vec<Type>>,
         value_arguments: Option<Vec<Value>>,
         variables: &HashMap<Identifier, Value>,
-    ) -> Result<Option<Value>, VmError<()>> {
+    ) -> Result<Option<Value>, VmError> {
         let mut new_variables = variables.clone();
 
         if let (Some(value_parameters), Some(value_arguments)) =
diff --git a/dust-lang/src/vm.rs b/dust-lang/src/vm.rs
index 314b8fd..3a09233 100644
--- a/dust-lang/src/vm.rs
+++ b/dust-lang/src/vm.rs
@@ -8,7 +8,7 @@ use crate::{
 pub fn run(
     input: &str,
     variables: &mut HashMap<Identifier, Value>,
-) -> Result<Option<Value>, VmError<Span>> {
+) -> Result<Option<Value>, VmError> {
     let abstract_syntax_tree = parse(input)?;
     let analyzer = Analyzer::new(&abstract_syntax_tree, variables);
 
@@ -19,19 +19,19 @@ pub fn run(
     vm.run(variables)
 }
 
-pub struct Vm<P> {
-    abstract_tree: AbstractSyntaxTree<P>,
+pub struct Vm {
+    abstract_tree: AbstractSyntaxTree,
 }
 
-impl<P: Copy> Vm<P> {
-    pub fn new(abstract_tree: AbstractSyntaxTree<P>) -> Self {
+impl Vm {
+    pub fn new(abstract_tree: AbstractSyntaxTree) -> Self {
         Self { abstract_tree }
     }
 
     pub fn run(
         &mut self,
         variables: &mut HashMap<Identifier, Value>,
-    ) -> Result<Option<Value>, VmError<P>> {
+    ) -> Result<Option<Value>, VmError> {
         let mut previous_value = None;
 
         while let Some(node) = self.abstract_tree.nodes.pop_front() {
@@ -43,9 +43,9 @@ impl<P: Copy> Vm<P> {
 
     fn run_node(
         &self,
-        node: Node<P>,
+        node: Node,
         variables: &mut HashMap<Identifier, Value>,
-    ) -> Result<Option<Value>, VmError<P>> {
+    ) -> Result<Option<Value>, VmError> {
         match node.statement {
             Statement::Add(left, right) => {
                 let left_span = left.position;
@@ -158,13 +158,7 @@ impl<P: Copy> Vm<P> {
                     None
                 };
 
-                Ok(function
-                    .clone()
-                    .call(None, value_parameters, variables)
-                    .map_err(|error| VmError::FunctionCallFailed {
-                        error: Box::new(error),
-                        position: function_position,
-                    })?)
+                Ok(function.clone().call(None, value_parameters, variables)?)
             }
             Statement::Identifier(_) => Ok(None),
             Statement::List(nodes) => {
@@ -178,7 +172,7 @@ impl<P: Copy> Vm<P> {
                             Err(VmError::ExpectedValue { position: span })
                         }
                     })
-                    .collect::<Result<Vec<Value>, VmError<P>>>()?;
+                    .collect::<Result<Vec<Value>, VmError>>()?;
 
                 Ok(Some(Value::list(values)))
             }
@@ -244,54 +238,40 @@ impl<P: Copy> Vm<P> {
 }
 
 #[derive(Clone, Debug, PartialEq)]
-pub enum VmError<P> {
-    AnaylyzerError(AnalyzerError<P>),
+pub enum VmError {
+    AnaylyzerError(AnalyzerError),
     ParseError(ParseError),
     ValueError(ValueError),
 
     // Anaylsis Failures
     // These should be prevented by running the analyzer before the VM
     BuiltInFunctionCallFailed(BuiltInFunctionError),
-    ExpectedIdentifier {
-        position: P,
-    },
-    ExpectedIdentifierOrInteger {
-        position: P,
-    },
-    ExpectedInteger {
-        position: P,
-    },
-    ExpectedList {
-        position: P,
-    },
-    ExpectedValue {
-        position: P,
-    },
-    FunctionCallFailed {
-        error: Box<VmError<()>>,
-        position: P,
-    },
+    ExpectedIdentifier { position: Span },
+    ExpectedIdentifierOrInteger { position: Span },
+    ExpectedInteger { position: Span },
+    ExpectedList { position: Span },
+    ExpectedValue { position: Span },
 }
 
-impl<P> From<BuiltInFunctionError> for VmError<P> {
+impl From<BuiltInFunctionError> for VmError {
     fn from(v: BuiltInFunctionError) -> Self {
         Self::BuiltInFunctionCallFailed(v)
     }
 }
 
-impl<P> From<AnalyzerError<P>> for VmError<P> {
-    fn from(error: AnalyzerError<P>) -> Self {
+impl From<AnalyzerError> for VmError {
+    fn from(error: AnalyzerError) -> Self {
         Self::AnaylyzerError(error)
     }
 }
 
-impl<P> From<ParseError> for VmError<P> {
+impl From<ParseError> for VmError {
     fn from(error: ParseError) -> Self {
         Self::ParseError(error)
     }
 }
 
-impl<P> From<ValueError> for VmError<P> {
+impl From<ValueError> for VmError {
     fn from(error: ValueError) -> Self {
         Self::ValueError(error)
     }