diff --git a/src/main.rs b/src/main.rs
index f032633..a8362cc 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,7 +2,6 @@ use std::io;
 use std::io::Write;
 //use std::io::Read;
 use std::sync::Arc;
-use std::collections::VecDeque;
 use std::sync::atomic::{AtomicBool, Ordering};
 
 use termcolor::{
@@ -13,7 +12,7 @@ use termcolor::{
 	WriteColor
 };
 
-pub mod tokenize;
+mod parser;
 
 const PROMPT_PREFIX: &str = "==> ";
 
@@ -61,93 +60,6 @@ fn prompt(
 }
 
 
-fn treefold(
-	mut exp: tokenize::Token, // Must be a group
-	check: fn(&tokenize::Token) -> bool,
-	op_type: u8,
-	new_token: fn(VecDeque<tokenize::Token>) -> tokenize::Token,
-) -> Result<tokenize::Token, ()> {
-
-	// Groups to process
-	let mut t_vec: VecDeque<&mut tokenize::Token> = VecDeque::with_capacity(32);
-	t_vec.push_back(&mut exp);
-
-	let mut out: Option<tokenize::Token> = None;
-
-	while t_vec.len() > 0 {
-
-		// The group we're currently working with
-		let g: &mut tokenize::Token = t_vec.pop_front().unwrap();
-		let g_inner: &mut VecDeque<tokenize::Token> = match g {
-			tokenize::Token::Group(ref mut x) => x,
-			_ => panic!()
-		};
-
-		let mut new: VecDeque<tokenize::Token> = VecDeque::with_capacity(8);
-
-		// Build new group array
-		while g_inner.len() > 0 {
-			let t: tokenize::Token = match g_inner.pop_front() {
-				Some(o) => o,
-				None => break
-			};
-
-			if check(&t) {
-				match op_type {
-					0 => {},
-					1 => {},
-					2 => {
-						let mut last: tokenize::Token = new.pop_back().unwrap();
-						let mut next: tokenize::Token = g_inner.pop_front().unwrap().clone();
-
-						// TODO: append to t_vec, do this without recursion.
-						if let tokenize::Token::Group(_) = last {
-							last = treefold(last, check, op_type, new_token).unwrap();
-						}
-						if let tokenize::Token::Group(_) = next {
-							next = treefold(next, check, op_type, new_token).unwrap();
-						}
-
-						let mut new_token_args: VecDeque<tokenize::Token> = VecDeque::with_capacity(2);
-						new_token_args.push_back(last);
-						new_token_args.push_back(next);
-						new.push_back(new_token(new_token_args));
-					},
-					_ => panic!()
-				};
-			} else {
-				new.push_back(t.clone());
-			}
-		}
-
-		*g_inner = new;
-	}
-	return Ok(exp);
-}
-
-
-fn is_mult(t: &tokenize::Token) -> bool {
-	match t {
-		tokenize::Token::Operator(s) => {s == "*"},
-		_ => false
-	}
-}
-
-fn new_mult(v: VecDeque<tokenize::Token>) -> tokenize::Token {
-	tokenize::Token::Mult(v)
-}
-
-fn is_add(t: &tokenize::Token) -> bool {
-	match t {
-		tokenize::Token::Operator(s) => {s == "+"},
-		_ => false
-	}
-}
-
-fn new_add(v: VecDeque<tokenize::Token>) -> tokenize::Token {
-	tokenize::Token::Add(v)
-}
-
 fn main() -> Result<(), std::io::Error> {
 
 	let mut stdout = StandardStream::stdout(ColorChoice::Always);
@@ -167,7 +79,7 @@ fn main() -> Result<(), std::io::Error> {
 
 		// Tokenize input.
 		// Fail if we encounter invalid characters.
-		let exp = match tokenize::tokenize(&input) {
+		let mut exp = match parser::tokenize::tokenize(&input) {
 			Ok(v) => v,
 			Err(_) => {
 				continue;
@@ -180,12 +92,9 @@ fn main() -> Result<(), std::io::Error> {
 		stdout.reset()?;
 		write!(stdout, "Got {input}\n\n\n")?;
 
-		//writeln!(stdout, "Tokenized: {exp:#?}")?;
+		parser::treefold::treefold(&mut exp).expect("Could not fold");
 
-
-		let mut q = treefold(exp, is_mult, 2, new_mult).unwrap();
-		q = treefold(q, is_add, 2, new_add).unwrap();
-		writeln!(stdout, "{q:#?}")?;
+		writeln!(stdout, "Tokenized: {exp:#?}")?;
 	}
 
 	writeln!(stdout, "Exiting.")?;
diff --git a/src/parser.rs b/src/parser.rs
new file mode 100644
index 0000000..26e9e57
--- /dev/null
+++ b/src/parser.rs
@@ -0,0 +1,2 @@
+pub mod tokenize;
+pub mod treefold;
\ No newline at end of file
diff --git a/src/tokenize.rs b/src/parser/tokenize.rs
similarity index 93%
rename from src/tokenize.rs
rename to src/parser/tokenize.rs
index adb2407..4b57833 100644
--- a/src/tokenize.rs
+++ b/src/parser/tokenize.rs
@@ -9,15 +9,19 @@ pub enum Token {
 	Negative,
 	Factorial,
 	Group(VecDeque<Token>), // Will be expanded during tree folding
-	Operator(String),  // Will become Ops during tree folding
+	Operator(String),       // Will become Ops during tree folding
 
-	// Used in both.
+	// Used in both
 	Number(String),
 	Word(String),
 
 	// Only used in tree
-	Mult(VecDeque<Token>),
-	Add(VecDeque<Token>)
+	Multiply(VecDeque<Token>),
+	Divide(VecDeque<Token>),
+	Add(VecDeque<Token>),
+	Subtract(VecDeque<Token>),
+	Fac(VecDeque<Token>),
+	Neg(VecDeque<Token>)
 }
 
 
diff --git a/src/parser/treefold.rs b/src/parser/treefold.rs
new file mode 100644
index 0000000..f926a4b
--- /dev/null
+++ b/src/parser/treefold.rs
@@ -0,0 +1,145 @@
+use std::collections::VecDeque;
+
+use crate::parser::tokenize::Token;
+
+fn treefold_one(
+	exp: &mut Token, // Must be a group
+	check: fn(&Token) -> bool,
+	op_type: u8,
+	new_token: fn(VecDeque<Token>) -> Token,
+) -> Result<(), ()> {
+
+	// Groups to process
+	let mut t_vec: VecDeque<&mut Token> = VecDeque::with_capacity(32);
+	t_vec.push_back(exp);
+
+	while t_vec.len() > 0 {
+
+		// The group we're currently working with
+		let g: &mut Token = t_vec.pop_front().unwrap();
+		let g_inner: &mut VecDeque<Token> = match g {
+			Token::Group(ref mut x) => x,
+			_ => panic!()
+		};
+
+		let mut new: VecDeque<Token> = VecDeque::with_capacity(8);
+
+		// Build new group array
+		while g_inner.len() > 0 {
+			let t: Token = match g_inner.pop_front() {
+				Some(o) => o,
+				None => break
+			};
+
+			if check(&t) {
+				match op_type {
+					0 => {
+						let mut last: Token = new.pop_back().unwrap();
+
+						if let Token::Group(_) = last {
+							treefold_one(&mut last, check, op_type, new_token).unwrap();
+						}
+
+						let mut new_token_args: VecDeque<Token> = VecDeque::with_capacity(1);
+						new_token_args.push_back(last);
+						new.push_back(new_token(new_token_args));
+					},
+					1 => {
+						let mut next: Token = g_inner.pop_front().unwrap().clone();
+
+						if let Token::Group(_) = next {
+							treefold_one(&mut next, check, op_type, new_token).unwrap();
+						}
+
+						let mut new_token_args: VecDeque<Token> = VecDeque::with_capacity(1);
+						new_token_args.push_back(next);
+						new.push_back(new_token(new_token_args));
+					},
+					2 => {
+						let mut last: Token = new.pop_back().unwrap();
+						let mut next: Token = g_inner.pop_front().unwrap().clone();
+
+						// TODO: append to t_vec, do this without recursion.
+						if let Token::Group(_) = last {
+							treefold_one(&mut last, check, op_type, new_token).unwrap();
+						}
+						if let Token::Group(_) = next {
+							treefold_one(&mut next, check, op_type, new_token).unwrap();
+						}
+
+						let mut new_token_args: VecDeque<Token> = VecDeque::with_capacity(2);
+						new_token_args.push_back(last);
+						new_token_args.push_back(next);
+						new.push_back(new_token(new_token_args));
+					},
+					_ => panic!()
+				};
+			} else {
+				new.push_back(t.clone());
+			}
+		}
+
+		*g_inner = new;
+	}
+
+	Ok(())
+}
+
+
+fn is_mult(t: &Token) -> bool {
+	match t {
+		Token::Operator(s) => {s == "*"},
+		_ => false
+	}
+}
+fn new_mult(v: VecDeque<Token>) -> Token { Token::Multiply(v) }
+
+fn is_add(t: &Token) -> bool {
+	match t {
+		Token::Operator(s) => {s == "+"},
+		_ => false
+	}
+}
+fn new_add(v: VecDeque<Token>) -> Token { Token::Add(v) }
+
+fn is_div(t: &Token) -> bool {
+	match t {
+		Token::Operator(s) => {s == "/"},
+		_ => false
+	}
+}
+fn new_div(v: VecDeque<Token>) -> Token { Token::Divide(v) }
+
+fn is_sub(t: &Token) -> bool {
+	match t {
+		Token::Operator(s) => {s == "-"},
+		_ => false
+	}
+}
+fn new_sub(v: VecDeque<Token>) -> Token { Token::Subtract(v) }
+
+fn is_fac(t: &Token) -> bool {
+	match t {
+		Token::Factorial => true,
+		_ => false
+	}
+}
+fn new_fac(v: VecDeque<Token>) -> Token { Token::Fac(v) }
+
+fn is_neg(t: &Token) -> bool {
+	match t {
+		Token::Negative => true,
+		_ => false
+	}
+}
+fn new_neg(v: VecDeque<Token>) -> Token { Token::Neg(v) }
+
+pub fn treefold(exp: &mut Token) -> Result<(), ()> {
+	treefold_one(exp, is_fac, 0, new_fac)?;
+	treefold_one(exp, is_neg, 1, new_neg)?;
+	treefold_one(exp, is_mult, 2, new_mult)?;
+	treefold_one(exp, is_div, 2, new_div)?;
+	treefold_one(exp, is_add, 2, new_add)?;
+	treefold_one(exp, is_sub, 2, new_sub)?;
+	Ok(())
+}
\ No newline at end of file