Added basic number parser

README.md

@@ -2,7 +2,7 @@
  - Fix documentation and variable names
  - implicit multiply
  - Function application
- - Syntax check (parenthesis, argument type)
+ - Syntax check (parenthesis, argument type, position of error)
 
 # Eventually
  - rationals

src/parser/replace_words.rs

@@ -20,6 +20,14 @@ pub fn replace_words(g: &mut Token) -> Result<(), ()> {
 				replace_words(&mut t)?;
 				new.push_back(t);
 			},
+			Token::PreNumber(ref s) => {
+				let n = match s.parse() {
+					Ok(n) => n,
+					Err(_) => panic!()
+				};
+
+				new.push_back(Token::Number(n));
+			}
 			Token::PreWord(ref s) => {
 				if s == "to" {
 					new.push_back(Token::PreOperator(String::from("to")));

src/parser/tokenize.rs

@@ -11,7 +11,13 @@ pub enum Token {
 	PreNumber(String),
 	PreWord(String),
 
+	// All PreGroups should vanish after operator folding
+	// All PreOperators should become Operators
+	// All PreNumbers should become Numbers
+	// All PreWords should become TODO.
+
 	// Only used in tree
+	Number(f64),
 	Multiply(VecDeque<Token>),
 	Divide(VecDeque<Token>),
 	Add(VecDeque<Token>),