cycle detecion on cart print - no longer stack overflow

ablescript/src/value/mod.rs

@@ -148,13 +148,12 @@ impl Display for Value {
                 cart_vec.sort_by(|x, y| x.0.partial_cmp(y.0).unwrap_or(std::cmp::Ordering::Less));
 
                 for (idx, (key, value)) in cart_vec.into_iter().enumerate() {
-                    write!(
-                        f,
-                        "{}{} <= {}",
-                        if idx != 0 { ", " } else { "" },
-                        value.borrow(),
-                        key
-                    )?;
+                    write!(f, "{}", if idx != 0 { ", " } else { "" },)?;
+                    match &*value.borrow() {
+                        x if std::ptr::eq(x, self) => write!(f, "<cycle>"),
+                        x => write!(f, "{x}"),
+                    }?;
+                    write!(f, " <= {key}")?;
                 }
 
                 write!(f, "]")