From b023686c815311ed69756b0a68a019dedac0dbc9 Mon Sep 17 00:00:00 2001
From: Jordan Orelli <jordanorelli@gmail.com>
Date: Sun, 21 Oct 2012 13:21:38 -0400
Subject: [PATCH] added support for unary -

---
 lex.go | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/lex.go b/lex.go
index 1d28262..9abbdd4 100644
--- a/lex.go
+++ b/lex.go
@@ -109,6 +109,26 @@ func lexOpenParen(l *lexer) (stateFn, error) {
 	case '.':
 		l.keep()
 		return lexFloat, nil
+	case '-':
+		l.keep()
+		return lexMinus, nil
+	}
+	if isDigit(l.cur) {
+		l.keep()
+		return lexInt, nil
+	}
+	l.keep()
+	return lexSymbol, nil
+}
+
+func lexMinus(l *lexer) (stateFn, error) {
+	switch l.cur {
+	case ' ', '\t', '\n', '\r':
+		l.emit(symbolToken)
+		return lexWhitespace, nil
+	case '.':
+		l.keep()
+		return lexFloat, nil
 	}
 	if isDigit(l.cur) {
 		l.keep()
@@ -137,6 +157,9 @@ func lexWhitespace(l *lexer) (stateFn, error) {
 	case '.':
 		l.keep()
 		return lexFloat, nil
+	case '-':
+		l.keep()
+		return lexMinus, nil
 	}
 	if isDigit(l.cur) {
 		l.keep()