allow minus operator, improve display for exprs

1 files changed, 6 insertions, 1 deletions

diff --git a/src/lisp/lex.rs b/src/lisp/lex.rs
index 30f49fa..a7b9586 100644
--- a/src/lisp/lex.rs
+++ b/src/lisp/lex.rs
@@ -115,11 +115,13 @@ impl<'a> Lexer<'a> {
 
 fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), LispError> {
     let mut dot = false;
+    let mut minus = false;
     let mut size = 0;
     let mut chars = input.chars();
 
     if let Some(v) = chars.next() {
         if v == '-' {
+            minus = true;
             size += 1;
             input = &input[1..];
         } else if v.is_digit(10) {
@@ -143,7 +145,10 @@ fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), LispError>
             return Err(LispError::ParseError);
         }
     }
-    let tok = if dot {
+
+    let tok = if size == 1 && minus {
+        Token::Name("-")
+    } else if dot {
         Token::Float(&input[..size])
     } else {
         Token::Integer(&input[..size])