Add manual impl of fmt::Debug to Expression

src/parser/nodes.rs

@@ -2,6 +2,8 @@
  * Eryn Wells <eryn@erynwells.me>
  */
 
+use std::fmt;
+
 use lexer;
 use types;
 
@@ -18,5 +20,17 @@ impl Program {
 pub enum Expression {
     EOF,
     Atom(Box<types::Value>),
-    List { left: lexer::Token, expression: Vec<Box<Expression>>, right: lexer::Token },
+    List { left: lexer::Token, expr: Vec<Box<Expression>>, right: lexer::Token },
+}
+
+impl fmt::Debug for Expression {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Expression::EOF => write!(f, "EOF"),
+            Expression::Atom(ref value) => write!(f, "Atom{{ {:?} }}", value),
+            Expression::List{ left: ref lt, expr: ref expr, right: ref rt } => {
+                write!(f, "{:?} {:?} {:?}", lt, expr, rt)
+            },
+        }
+    }
 }