more complex tests

src/lex.rs

@@ -164,7 +164,7 @@ fn process(document: String) -> Result<Ast, String> {
                 } else if let Some(s) = tok_is_symbol(&token) {
                     obj = Ctr::Symbol(s);
                 } else {
-                    return Err(format!("Unparsable token:{}", token));
+                    return Err(format!("Unparsable token: {}", token));
                 }
 
                 token = String::new();
@@ -195,14 +195,14 @@ fn process(document: String) -> Result<Ast, String> {
 
 
 /* Returns true if token
- *   - is all alphanumeric
+ *   - is all alphanumeric except dash and underscore
  *
  * else returns false
  */
 fn tok_is_symbol(token: &String) -> Option<String> {
     let tok = token.as_str();
     for t in tok.chars() {
-        if !t.is_alphabetic() && !t.is_digit(10) {
+        if !t.is_alphabetic() && !t.is_digit(10) && !(t == '-') && !(t == '_') {
             return None
         }
     }