Finished up to and including chapter 16

vm/src/value.rs

@@ -0,0 +1,22 @@
+use std::fmt::Display;
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum Value {
+    Nil,
+    Number(f64),
+}
+
+impl Default for Value {
+    fn default() -> Self {
+        Value::Nil
+    }
+}
+
+impl Display for Value {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Value::Nil => write!(f, "nil"),
+            Value::Number(num) => write!(f, "{num}"),
+        }
+    }
+}