feat: no clone in JIT

IMPORTANT: should not drop or create values in JIT anymore

src/vm/env.rs

@@ -1,5 +1,5 @@
-use std::{hash::Hash, rc::Rc};
 use std::fmt::Debug;
+use std::{hash::Hash, rc::Rc};
 
 use hashbrown::HashMap;
 
@@ -7,21 +7,24 @@ use crate::ty::internal::{AttrSet, Value};
 
 pub struct Env<K: Hash + Eq, V> {
     map: Node<K, V>,
-    last: Option<Rc<Env<K, V>>>
+    last: Option<Rc<Env<K, V>>>,
 }
 
 impl<K: Clone + Hash + Eq, V: Clone> Clone for Env<K, V> {
     fn clone(&self) -> Self {
         Self {
             map: self.map.clone(),
-            last: self.last.clone()
+            last: self.last.clone(),
         }
     }
 }
 
 impl<K: Debug + Hash + Eq, V: Debug> Debug for Env<K, V> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct("Env").field("map", &self.map).field("last", &self.last).finish()
+        f.debug_struct("Env")
+            .field("map", &self.map)
+            .field("last", &self.last)
+            .finish()
     }
 }
 
@@ -86,7 +89,8 @@ impl<K: Hash + Eq, V> Env<K, V> {
 
     pub fn enter_with(self: Rc<Self>, map: Rc<HashMap<K, V>>) -> Rc<Self> {
         let map = Node::Let(map);
-        let last = Some(self);Env { last, map }.into()
+        let last = Some(self);
+        Env { last, map }.into()
     }
 
     pub fn leave(self: Rc<Self>) -> Rc<Self> {