diff --git a/compiler/erg_common/traits.rs b/compiler/erg_common/traits.rs
index 10017ba6..282adfdb 100644
--- a/compiler/erg_common/traits.rs
+++ b/compiler/erg_common/traits.rs
@@ -357,6 +357,9 @@ pub trait Runnable: Sized + Default {
     fn new(cfg: ErgConfig) -> Self;
     fn cfg(&self) -> &ErgConfig;
     fn finish(&mut self); // called when the :exit command is received.
+    /// Erase all but immutable information.
+    fn initialize(&mut self);
+    /// Erase information that will no longer be meaningful in the next iteration
     fn clear(&mut self);
     fn eval(&mut self, src: String) -> Result<String, Self::Errs>;
     fn exec(&mut self) -> Result<i32, Self::Errs>;
diff --git a/compiler/erg_compiler/build_hir.rs b/compiler/erg_compiler/build_hir.rs
index 921fd81e..0434f100 100644
--- a/compiler/erg_compiler/build_hir.rs
+++ b/compiler/erg_compiler/build_hir.rs
@@ -45,7 +45,15 @@ impl Runnable for HIRBuilder {
     #[inline]
     fn finish(&mut self) {}
 
-    fn clear(&mut self) {}
+    fn initialize(&mut self) {
+        self.lowerer.initialize();
+        self.ownership_checker = OwnershipChecker::new(self.cfg().copy());
+    }
+
+    fn clear(&mut self) {
+        self.lowerer.clear();
+        self.ownership_checker = OwnershipChecker::new(self.cfg().copy());
+    }
 
     fn exec(&mut self) -> Result<i32, Self::Errs> {
         let mut builder = ASTBuilder::new(self.cfg().copy());
diff --git a/compiler/erg_compiler/compile.rs b/compiler/erg_compiler/compile.rs
index acc527b9..f7a74809 100644
--- a/compiler/erg_compiler/compile.rs
+++ b/compiler/erg_compiler/compile.rs
@@ -129,7 +129,14 @@ impl Runnable for Compiler {
     #[inline]
     fn finish(&mut self) {}
 
+    fn initialize(&mut self) {
+        self.builder.initialize();
+        self.code_generator.clear();
+        // .mod_cache will be initialized in .builder
+    }
+
     fn clear(&mut self) {
+        self.builder.clear();
         self.code_generator.clear();
     }
 
diff --git a/compiler/erg_compiler/context/mod.rs b/compiler/erg_compiler/context/mod.rs
index 90957cdf..a4d5a7f5 100644
--- a/compiler/erg_compiler/context/mod.rs
+++ b/compiler/erg_compiler/context/mod.rs
@@ -900,6 +900,29 @@ impl Context {
         }
     }
 
+    /// This method is intended to be called __only__ in the top-level module.
+    /// `.cfg` is not initialized and is used around.
+    pub fn initialize(&mut self) {
+        let mut mod_cache = mem::take(&mut self.mod_cache);
+        if let Some(mod_cache) = &mut mod_cache {
+            mod_cache.initialize();
+        }
+        let mut py_mod_cache = mem::take(&mut self.py_mod_cache);
+        if let Some(py_mod_cache) = &mut py_mod_cache {
+            py_mod_cache.initialize();
+        }
+        *self = Self::new(
+            self.name.clone(),
+            self.cfg.clone(),
+            self.kind.clone(),
+            vec![],
+            None,
+            mod_cache,
+            py_mod_cache,
+            self.level,
+        );
+    }
+
     pub(crate) fn grow(
         &mut self,
         name: &str,
diff --git a/compiler/erg_compiler/lower.rs b/compiler/erg_compiler/lower.rs
index 3827169b..281c1be2 100644
--- a/compiler/erg_compiler/lower.rs
+++ b/compiler/erg_compiler/lower.rs
@@ -84,6 +84,12 @@ impl Runnable for ASTLowerer {
     #[inline]
     fn finish(&mut self) {}
 
+    fn initialize(&mut self) {
+        self.ctx.initialize();
+        self.errs.clear();
+        self.warns.clear();
+    }
+
     fn clear(&mut self) {
         self.errs.clear();
         self.warns.clear();
diff --git a/compiler/erg_compiler/mod_cache.rs b/compiler/erg_compiler/mod_cache.rs
index 24c3bb4f..6808855b 100644
--- a/compiler/erg_compiler/mod_cache.rs
+++ b/compiler/erg_compiler/mod_cache.rs
@@ -201,4 +201,16 @@ impl SharedModuleCache {
     pub fn get_similar_name(&self, name: &str) -> Option<Str> {
         self.0.borrow().get_similar_name(name)
     }
+
+    pub fn initialize(&mut self) {
+        let builtin_path = PathBuf::from("<builtins>");
+        let builtin = self.remove(&builtin_path).unwrap();
+        for path in self.0.borrow().cache.keys() {
+            self.remove(path);
+        }
+        /*for path in self.0.borrow().cache.keys().cloned() {
+            self.remove(&path);
+        }*/
+        self.register(builtin_path, None, Rc::try_unwrap(builtin.ctx).unwrap());
+    }
 }
diff --git a/compiler/erg_compiler/transpile.rs b/compiler/erg_compiler/transpile.rs
index af58354f..cc5bd0c9 100644
--- a/compiler/erg_compiler/transpile.rs
+++ b/compiler/erg_compiler/transpile.rs
@@ -65,8 +65,14 @@ impl Runnable for Transpiler {
     #[inline]
     fn finish(&mut self) {}
 
+    fn initialize(&mut self) {
+        self.builder.initialize();
+        // mod_cache will be cleared by the builder
+        // self.mod_cache.initialize();
+    }
+
     fn clear(&mut self) {
-        // self.builder.clear();
+        self.builder.clear();
     }
 
     fn exec(&mut self) -> Result<i32, Self::Errs> {
diff --git a/compiler/erg_parser/build_ast.rs b/compiler/erg_parser/build_ast.rs
index d2a33050..12a6e5e2 100644
--- a/compiler/erg_parser/build_ast.rs
+++ b/compiler/erg_parser/build_ast.rs
@@ -33,6 +33,9 @@ impl Runnable for ASTBuilder {
     #[inline]
     fn finish(&mut self) {}
 
+    #[inline]
+    fn initialize(&mut self) {}
+
     #[inline]
     fn clear(&mut self) {}
 
diff --git a/compiler/erg_parser/lex.rs b/compiler/erg_parser/lex.rs
index c38abd99..33b5e3a1 100644
--- a/compiler/erg_parser/lex.rs
+++ b/compiler/erg_parser/lex.rs
@@ -35,6 +35,9 @@ impl Runnable for LexerRunner {
     #[inline]
     fn finish(&mut self) {}
 
+    #[inline]
+    fn initialize(&mut self) {}
+
     #[inline]
     fn clear(&mut self) {}
 
diff --git a/compiler/erg_parser/parse.rs b/compiler/erg_parser/parse.rs
index bf8bd106..842192b1 100644
--- a/compiler/erg_parser/parse.rs
+++ b/compiler/erg_parser/parse.rs
@@ -187,6 +187,9 @@ impl Runnable for ParserRunner {
     #[inline]
     fn finish(&mut self) {}
 
+    #[inline]
+    fn initialize(&mut self) {}
+
     #[inline]
     fn clear(&mut self) {}
 
diff --git a/src/dummy.rs b/src/dummy.rs
index b132da3f..b6613a18 100644
--- a/src/dummy.rs
+++ b/src/dummy.rs
@@ -100,6 +100,10 @@ impl Runnable for DummyVM {
         }
     }
 
+    fn initialize(&mut self) {
+        self.compiler.initialize();
+    }
+
     fn clear(&mut self) {
         self.compiler.clear();
     }