Added "ans" variable

src/parser/pretoken.rs

@@ -83,6 +83,9 @@ impl PreToken {
 				let c = Unit::from_string(&s);
 				if c.is_some() { return Ok(Token::Quantity(c.unwrap())); }
 
+
+				if s == "ans" { return Ok(Token::Variable(String::from("ans"))); }
+
 				return Err((l, ParserError::Undefined(s)));
 			}
 

src/parser/stage/tokenize.rs

@@ -50,9 +50,9 @@ fn push_token(g: &mut VecDeque<PreToken>, t: Option<PreToken>, stop_i: usize) {
 		}
 	}
 
+	// Some operators are written as words.
 	if let PreToken::PreWord(l, s) = &t {
-		let o = Operator::from_string(s);
-		if o.is_some() {
+		if Operator::from_string(s).is_some() {
 			t = PreToken::PreOperator(*l, s.clone());
 		}
 	}

src/parser/token/token.rs

@@ -8,6 +8,7 @@ use super::Constant;
 #[derive(Debug)]
 #[derive(Clone)]
 pub enum Token {
+	Variable(String),
 	Quantity(Quantity),
 	Constant(Constant),
 	Operator(Operator, VecDeque<Token>),
@@ -18,6 +19,7 @@ impl ToString for Token {
 		match self {
 			Token::Quantity(v) => v.to_string(),
 			Token::Constant(c) => c.to_string(),
+			Token::Variable(s) => s.clone(),
 			Token::Operator(o,a) => o.print(a)
 		}
 	}
@@ -30,6 +32,7 @@ impl Token {
 		match self {
 			Token::Quantity(v) => v.to_string_outer(),
 			Token::Constant(c) => c.to_string(),
+			Token::Variable(s) => s.clone(),
 			Token::Operator(o,a) => o.print(a)
 		}
 	}