do no parse negatives

src/parse/lexer.rs

@@ -167,7 +167,8 @@ impl<'s, T: Iterator<Item = (usize, char)>> Lexer<'s, T> {
     }
 
     fn is_number_start(&self, c: char, c1: Option<char>) -> bool {
-        c.is_ascii_digit() || (c == '-' && c1.map_or(false, |c| c.is_ascii_digit()))
+        c.is_ascii_digit()
+            // || (c == '-' && c1.map_or(false, |c| c.is_ascii_digit()))
     }
 
     fn is_digit(&self, c: char) -> bool {