diff --git a/Cargo.toml b/Cargo.toml
index 7cbb650..bd20c9e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,4 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-socket2 = "0.5.3"
+rand = "0.8.5"
diff --git a/src/assembly.rs b/src/assembly.rs
deleted file mode 100644
index be9cfee..0000000
--- a/src/assembly.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-use crate::tokeniser::Token;
-
-pub fn assemblize(tokens: Vec<Token>) -> String {
-    let mut output = String::new();
-
-    for token in tokens {
-        output += "hii"
-    }
-
-    output
-}
diff --git a/src/ast.rs b/src/ast.rs
new file mode 100644
index 0000000..8c56714
--- /dev/null
+++ b/src/ast.rs
@@ -0,0 +1,357 @@
+extern crate rand;
+
+use rand::{distributions::Alphanumeric, Rng};
+use std::collections::HashMap;
+
+#[derive(Debug, Clone)]
+pub struct Function {
+    pub name: String,
+    pub statements: Vec<Statement>,
+    assembly: Option<String>,
+}
+
+#[derive(Debug, Clone)]
+pub enum Statement {
+    FunctionCall(String, Vec<ValueNode>),
+    VariableDeclaration(String, ValueNode),
+}
+
+#[derive(Debug, Clone)]
+pub enum ValueNode {
+    Literal(Literal),
+    Operator(Operator),
+}
+
+#[derive(Debug, Clone)]
+pub enum Literal {
+    Int(i64),
+}
+
+#[derive(Debug, Clone)]
+pub enum Operator {
+    Add(Box<ValueNode>, Box<ValueNode>),
+    Sub(Box<ValueNode>, Box<ValueNode>),
+}
+
+#[derive(Debug, Clone)]
+pub struct AssemblerState {
+    pub functions: HashMap<String, Function>,
+}
+
+pub trait Node {
+    fn to_assembly(&self, state: &mut AssemblerState) -> String;
+}
+
+impl Function {
+    pub fn new(name: String, statements: Vec<Statement>) -> Function {
+        Function {
+            name,
+            statements,
+            assembly: None,
+        }
+    }
+
+    pub fn add(&self, state: &mut AssemblerState) -> Function {
+        state.functions.insert(self.name.clone(), self.to_owned());
+        self.to_owned()
+    }
+}
+
+impl AssemblerState {
+    pub fn new() -> AssemblerState {
+        AssemblerState {
+            functions: get_default_functions(),
+        }
+    }
+}
+
+fn get_default_functions() -> HashMap<String, Function> {
+    let mut functions = HashMap::new();
+    functions.insert(
+        "out".to_string(),
+        Function {
+            name: "exit".to_string(),
+            statements: vec![],
+            assembly: Some(
+                "
+out:
+;
+; Pop the argument of the stack
+;
+
+SE-OUT  RAM-ADDR-U-IN 0xFF ; Set ram address to stack end
+RAM-OUT OUTPUT-IN     0xFF ; Output top address onto output register
+
+ROM-OUT FLAGS-IN      0x80 ; Subtract mode
+SE-OUT  A-IN          0xFF ; Fetch SE
+ROM-OUT B-IN          0x01 ; Subtract one
+ALU-OUT SE-IN         0xFF ; Store in SE
+ROM-OUT FLAGS-IN      0x00 ; Add mode
+
+;
+; Pop the return address of the stack
+;
+
+SE-OUT  RAM-ADDR-U-IN 0xFF ; Set ram address to stack end
+RAM-OUT ROM-ADDR-U-IN 0xFF ; Store top address in ROM jump address
+
+ROM-OUT FLAGS-IN      0x80 ; Subtract mode
+SE-OUT  A-IN          0xFF ; Fetch SE
+ROM-OUT B-IN          0x01 ; Subtract one
+ALU-OUT SE-IN         0xFF ; Store in SE
+ROM-OUT FLAGS-IN      0x00 ; Add mode
+
+F-OUT   JMP           0xFF"
+                    .to_string(),
+            ),
+        },
+    );
+    functions.insert(
+        "exit".to_string(),
+        Function {
+            name: "exit".to_string(),
+            statements: vec![],
+            assembly: Some(
+                "
+exit:
+F-OUT JMP 0xFF"
+                    .to_string(),
+            ),
+        },
+    );
+    functions
+}
+
+impl Node for Function {
+    fn to_assembly(&self, state: &mut AssemblerState) -> String {
+        match &self.assembly {
+            Some(v) => v.to_string(),
+            None => format!(
+                "{}:\n{}
+;
+; Pop the return address of the stack
+;
+
+SE-OUT  RAM-ADDR-U-IN 0xFF ; Set ram address to stack end
+RAM-OUT ROM-ADDR-U-IN 0xFF ; Store top address in ROM jump address
+
+ROM-OUT FLAGS-IN      0x80 ; Subtract mode
+SE-OUT  A-IN          0xFF ; Fetch SE
+ROM-OUT B-IN          0x01 ; Subtract one
+ALU-OUT SE-IN         0xFF ; Store in SE
+ROM-OUT FLAGS-IN      0x00 ; Add mode
+
+F-OUT   JMP           0xFF
+",
+                self.name,
+                {
+                    self.statements
+                        .iter()
+                        .map(|x| x.to_assembly(state))
+                        .collect::<Vec<String>>()
+                        .join("\n")
+                }
+            ),
+        }
+    }
+}
+
+impl Node for Statement {
+    fn to_assembly(&self, state: &mut AssemblerState) -> String {
+        match self {
+            Statement::FunctionCall(name, arguments) => {
+                if !state.functions.contains_key(name) {
+                    todo!()
+                }
+
+                let argument_assembly: String = arguments
+                    .into_iter()
+                    .map(|x| x.to_assembly(state))
+                    .collect::<Vec<String>>()
+                    .join("\n");
+
+                let call_id: String = rand::thread_rng()
+                    .sample_iter(&Alphanumeric)
+                    .take(30)
+                    .map(char::from)
+                    .collect();
+
+                format!(
+                    "
+;
+; Stack
+;
+
+; Increment Stack Pointer
+
+SE-OUT  A-IN  0xFF ; Fetch SE
+ROM-OUT B-IN  0x01 ; Add 1
+ALU-OUT SE-IN 0xFF ; Store
+
+; Store in top stack pointer
+
+ALU-OUT RAM-ADDR-U-IN 0xFF ; Store in RAM address
+ROM-OUT RAM-IN        ${name}-{call_id}  ; Store address after jump in ram
+
+;
+; Arguments
+; 
+
+{argument_assembly}
+
+;
+; Jump
+;
+ROM-OUT ROM-ADDR-U-IN ${name}  ; Jump to function label
+F-OUT   JMP           0xFF ; Jump to function
+
+{name}-{call_id}:
+"
+                )
+            }
+            Statement::VariableDeclaration(_name, _value) => {
+                todo!()
+            }
+        }
+    }
+}
+
+impl Node for ValueNode {
+    fn to_assembly(&self, state: &mut AssemblerState) -> String {
+        match self {
+            ValueNode::Literal(v) => v.to_assembly(state),
+            ValueNode::Operator(o) => o.to_assembly(state),
+        }
+    }
+}
+
+impl Node for Literal {
+    fn to_assembly(&self, _state: &mut AssemblerState) -> String {
+        match self {
+            Literal::Int(v) => {
+                format!(
+                    "
+;
+; Stack
+;
+
+; Increment Stack Pointer
+
+SE-OUT  A-IN  0xFF ; Fetch SE
+ROM-OUT B-IN  0x01 ; Add 1
+ALU-OUT SE-IN 0xFF ; Store
+
+; Store in top stack pointer
+
+ALU-OUT RAM-ADDR-U-IN 0xFF ; Store in RAM address
+ROM-OUT RAM-IN        {v}; Store literal value in RAM"
+                )
+            }
+        }
+    }
+}
+
+impl Node for Operator {
+    fn to_assembly(&self, state: &mut AssemblerState) -> String {
+        match self {
+            Operator::Add(a, b) => {
+                format!(
+                    "
+{}
+{}
+
+SE-OUT  RAM-ADDR-U-IN 0xFF ; Set ram address to stack end
+RAM-OUT C-IN          0xFF ; Output top address onto output register
+
+ROM-OUT FLAGS-IN      0x80 ; Subtract mode
+SE-OUT  A-IN          0xFF ; Fetch SE
+ROM-OUT B-IN          0x01 ; Subtract one
+ALU-OUT SE-IN         0xFF ; Store in SE
+
+SE-OUT  RAM-ADDR-U-IN 0xFF ; Set ram address to stack end
+RAM-OUT D-IN          0xFF ; Output top address onto output register
+
+ROM-OUT FLAGS-IN      0x80 ; Subtract mode
+SE-OUT  A-IN          0xFF ; Fetch SE
+ROM-OUT B-IN          0x01 ; Subtract one
+ALU-OUT SE-IN         0xFF ; Store in SE
+ROM-OUT FLAGS-IN      0x00 ; Add mode
+
+C-OUT   A-IN          0xFF ; Move temporary values into a register for alu computation 
+D-OUT   B-IN          0xFF ; Move temporary values into a register for alu computation 
+ALU-OUT C-IN          0xFF ; Move ALU output into temporary register
+
+SE-OUT  A-IN  0xFF ; Fetch SE
+ROM-OUT B-IN  0x01 ; Add 1
+ALU-OUT SE-IN 0xFF ; Store
+
+ALU-OUT RAM-ADDR-U-IN 0xFF ; Store in RAM address
+C-OUT   RAM-IN        0xFF ; Store address after jump in ram
+",
+                    a.to_assembly(state),
+                    b.to_assembly(state)
+                )
+            }
+            Operator::Sub(a, b) => {
+                format!(
+                    "
+{}
+{}
+
+SE-OUT  RAM-ADDR-U-IN 0xFF ; Set ram address to stack end
+RAM-OUT C-IN          0xFF ; Output top address onto output register
+
+ROM-OUT FLAGS-IN      0x80 ; Subtract mode
+SE-OUT  A-IN          0xFF ; Fetch SE
+ROM-OUT B-IN          0x01 ; Subtract one
+ALU-OUT SE-IN         0xFF ; Store in SE
+
+SE-OUT  RAM-ADDR-U-IN 0xFF ; Set ram address to stack end
+RAM-OUT D-IN          0xFF ; Output top address onto output register
+
+ROM-OUT FLAGS-IN      0x80 ; Subtract mode
+SE-OUT  A-IN          0xFF ; Fetch SE
+ROM-OUT B-IN          0x01 ; Subtract one
+ALU-OUT SE-IN         0xFF ; Store in SE
+ROM-OUT FLAGS-IN      0x00 ; Add mode
+
+ROM-OUT FLAGS-IN      0x80 ; Subtract mode
+C-OUT   B-IN          0xFF ; Move temporary values into a register for alu computation 
+D-OUT   A-IN          0xFF ; Move temporary values into a register for alu computation 
+ALU-OUT C-IN          0xFF ; Move ALU output into temporary register
+ROM-OUT FLAGS-IN      0x00 ; Add mode
+
+SE-OUT  A-IN  0xFF ; Fetch SE
+ROM-OUT B-IN  0x01 ; Add 1
+ALU-OUT SE-IN 0xFF ; Store
+
+ALU-OUT RAM-ADDR-U-IN 0xFF ; Store in RAM address
+C-OUT   RAM-IN        0xFF ; Store address after jump in ram
+",
+                    a.to_assembly(state),
+                    b.to_assembly(state)
+                )
+            }
+        }
+    }
+}
+
+pub fn to_assembly(functions: Vec<Function>) -> String {
+    let mut final_product: String = "".to_owned();
+    let mut std_function_assembly = "".to_owned();
+    let mut state = AssemblerState::new();
+
+    for std_function in state.clone().functions {
+        std_function_assembly += &std_function.1.to_assembly(&mut state);
+    }
+
+    for standard_function in &functions {
+        standard_function.add(&mut state);
+    }
+
+    for standard_function in &functions {
+        final_product += &standard_function.to_assembly(&mut state);
+    }
+
+    final_product + &std_function_assembly
+}
diff --git a/src/tokeniser.rs b/src/tokeniser.rs
index ea7d96e..9eb505e 100644
--- a/src/tokeniser.rs
+++ b/src/tokeniser.rs
@@ -1,19 +1,29 @@
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum Token {
-    SEMI,
-    NUMBER(String),
-    IDENTIFIER(String),
-    KEYWORD(Keyword),
+    Semi,
+    Equals,
+    Comma,
+    Plus,
+    Minus,
+    Number(String),
+    Identifier(String),
+    Keyword(Keyword),
+    OpenParanthesis,
+    CloseParanthesis,
+    OpenSquiglyBracket,
+    CloseSquiglyBracket,
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum Keyword {
-    RETURN,
+    Return,
+    Function,
+    Let,
 }
 
 enum TokenFinishedUnfinished {
-    UNFINISHED(Option<Token>),
-    FINISHED(Token),
+    Unfinished(Option<Token>),
+    Finished(Token),
 }
 
 use std::collections::HashMap;
@@ -24,7 +34,9 @@ fn generate_keyword_map() -> HashMap<String, Keyword> {
     let mut keywords: HashMap<String, Keyword> = HashMap::new();
 
     use Keyword as K;
-    keywords.insert("return".to_string(), K::RETURN);
+    keywords.insert("return".to_string(), K::Return);
+    keywords.insert("fn".to_string(), K::Function);
+    keywords.insert("let".to_string(), K::Let);
 
     keywords
 }
@@ -36,46 +48,75 @@ fn tokenise_current_character(
     let keywords = generate_keyword_map();
 
     match current_token_type {
-        Some(Token::NUMBER(ref v)) => {
+        Some(Token::Number(ref v)) => {
             let mut current_characters = v.clone();
 
             if current_character.is_digit(10) {
                 current_characters.push(current_character);
-                return UNFINISHED(Some(Token::NUMBER(current_characters)));
+                return Unfinished(Some(Token::Number(current_characters)));
             }
 
-            FINISHED(Token::NUMBER(current_characters))
+            Finished(Token::Number(current_characters))
         }
-        Some(Token::IDENTIFIER(ref v)) => {
+        Some(Token::Identifier(ref v)) => {
             let mut current_characters = v.clone();
 
             if current_character.is_alphanumeric() {
                 current_characters.push(current_character);
-                return UNFINISHED(Some(Token::IDENTIFIER(current_characters)));
+                return Unfinished(Some(Token::Identifier(current_characters)));
             }
 
             match keywords.get(&current_characters) {
-                Some(keyword) => FINISHED(Token::KEYWORD(keyword.clone())),
-                None => FINISHED(Token::IDENTIFIER(current_characters)),
+                Some(keyword) => Finished(Token::Keyword(keyword.clone())),
+                None => Finished(Token::Identifier(current_characters)),
             }
         }
-        Some(Token::SEMI) => FINISHED(Token::SEMI), // Needed because we're always going back a step after returning finished token
         None => {
             if current_character.is_digit(10) {
-                return UNFINISHED(Some(Token::NUMBER(String::from(current_character))));
+                return Unfinished(Some(Token::Number(String::from(current_character))));
             }
 
             if current_character.is_alphabetic() {
-                return UNFINISHED(Some(Token::IDENTIFIER(String::from(current_character))));
+                return Unfinished(Some(Token::Identifier(String::from(current_character))));
             }
 
             if current_character == ';' {
-                return UNFINISHED(Some(Token::SEMI));
+                return Unfinished(Some(Token::Semi));
             }
 
-            UNFINISHED(None)
+            if current_character == '(' {
+                return Unfinished(Some(Token::OpenParanthesis));
+            }
+            if current_character == ')' {
+                return Unfinished(Some(Token::CloseParanthesis));
+            }
+
+            if current_character == '{' {
+                return Unfinished(Some(Token::OpenSquiglyBracket));
+            }
+            if current_character == '}' {
+                return Unfinished(Some(Token::CloseSquiglyBracket));
+            }
+
+            if current_character == '=' {
+                return Unfinished(Some(Token::Equals));
+            }
+
+            if current_character == ',' {
+                return Unfinished(Some(Token::Comma));
+            }
+
+            if current_character == '+' {
+                return Unfinished(Some(Token::Plus));
+            }
+
+            if current_character == '-' {
+                return Unfinished(Some(Token::Minus));
+            }
+
+            Unfinished(None)
         }
-        Some(v) => FINISHED(v),
+        Some(v) => Finished(v),
     }
 }
 
@@ -90,10 +131,10 @@ pub fn tokenise(input: String) -> Vec<Token> {
         current_character = input.as_bytes()[i] as char;
 
         match tokenise_current_character(current_character, current_token_type.clone()) {
-            UNFINISHED(v) => {
+            Unfinished(v) => {
                 current_token_type = v.clone();
             }
-            FINISHED(v) => {
+            Finished(v) => {
                 tokens.push(v);
                 current_token_type = None;
                 i -= 1;