diff --git a/crates/els/hir_visitor.rs b/crates/els/hir_visitor.rs
index 841f4c179..c75361479 100644
--- a/crates/els/hir_visitor.rs
+++ b/crates/els/hir_visitor.rs
@@ -186,7 +186,7 @@ impl<'a> HIRVisitor<'a> {
     ) -> Option<Vec<Str>> {
         let ns = class_def.sig.ident().to_string_notype();
         cur_ns.push(Str::from(ns));
-        self.get_exprs_ns(cur_ns, class_def.methods.iter(), pos)
+        self.get_exprs_ns(cur_ns, class_def.all_methods(), pos)
     }
 
     fn get_patch_def_ns(
@@ -282,7 +282,9 @@ impl<'a> HIRVisitor<'a> {
             Expr::Tuple(tuple) => self.get_expr_from_tuple(expr, tuple, pos),
             Expr::TypeAsc(type_asc) => self.get_expr(&type_asc.expr, pos),
             Expr::Dummy(dummy) => self.get_expr_from_dummy(dummy, pos),
-            Expr::Compound(block) | Expr::Code(block) => self.get_expr_from_block(block, pos),
+            Expr::Compound(block) | Expr::Code(block) => {
+                self.get_expr_from_block(block.iter(), pos)
+            }
             Expr::ReDef(redef) => self.get_expr_from_redef(expr, redef, pos),
             Expr::Import(_) => None,
         }
@@ -362,7 +364,7 @@ impl<'a> HIRVisitor<'a> {
         pos: Position,
     ) -> Option<&Expr> {
         self.return_expr_if_same(expr, def.sig.ident().raw.name.token(), pos)
-            .or_else(|| self.get_expr_from_block(&def.body.block, pos))
+            .or_else(|| self.get_expr_from_block(def.body.block.iter(), pos))
             .or_else(|| self.return_expr_if_contains(expr, pos, def))
     }
 
@@ -376,12 +378,16 @@ impl<'a> HIRVisitor<'a> {
             .require_or_sup
             .as_ref()
             .and_then(|req_sup| self.get_expr(req_sup, pos))
-            .or_else(|| self.get_expr_from_block(&class_def.methods, pos))
+            .or_else(|| self.get_expr_from_block(class_def.all_methods(), pos))
             .or_else(|| self.return_expr_if_contains(expr, pos, class_def))
     }
 
-    fn get_expr_from_block<'e>(&'e self, block: &'e Block, pos: Position) -> Option<&Expr> {
-        for chunk in block.iter() {
+    fn get_expr_from_block<'e>(
+        &'e self,
+        block: impl Iterator<Item = &'e Expr>,
+        pos: Position,
+    ) -> Option<&Expr> {
+        for chunk in block {
             if let Some(expr) = self.get_expr(chunk, pos) {
                 return Some(expr);
             }
@@ -396,7 +402,7 @@ impl<'a> HIRVisitor<'a> {
         pos: Position,
     ) -> Option<&Expr> {
         self.get_expr_from_acc(expr, &redef.attr, pos)
-            .or_else(|| self.get_expr_from_block(&redef.block, pos))
+            .or_else(|| self.get_expr_from_block(redef.block.iter(), pos))
     }
 
     fn get_expr_from_dummy<'e>(&'e self, dummy: &'e Dummy, pos: Position) -> Option<&Expr> {
@@ -416,7 +422,7 @@ impl<'a> HIRVisitor<'a> {
     ) -> Option<&Expr> {
         self.return_expr_if_same(expr, patch_def.sig.name().token(), pos)
             .or_else(|| self.get_expr(&patch_def.base, pos))
-            .or_else(|| self.get_expr_from_block(&patch_def.methods, pos))
+            .or_else(|| self.get_expr_from_block(patch_def.methods.iter(), pos))
             .or_else(|| self.return_expr_if_contains(expr, pos, patch_def))
     }
 
@@ -431,7 +437,7 @@ impl<'a> HIRVisitor<'a> {
         {
             return Some(expr);
         }
-        self.get_expr_from_block(&lambda.body, pos)
+        self.get_expr_from_block(lambda.body.iter(), pos)
     }
 
     fn get_expr_from_array<'e>(
@@ -487,7 +493,7 @@ impl<'a> HIRVisitor<'a> {
             return Some(expr);
         }
         for field in record.attrs.iter() {
-            if let Some(expr) = self.get_expr_from_block(&field.body.block, pos) {
+            if let Some(expr) = self.get_expr_from_block(field.body.block.iter(), pos) {
                 return Some(expr);
             }
         }
@@ -577,7 +583,7 @@ impl<'a> HIRVisitor<'a> {
             Expr::Tuple(tuple) => self.get_tuple_info(tuple, token),
             Expr::TypeAsc(type_asc) => self.get_tasc_info(type_asc, token),
             Expr::Dummy(dummy) => self.get_dummy_info(dummy, token),
-            Expr::Compound(block) | Expr::Code(block) => self.get_block_info(block, token),
+            Expr::Compound(block) | Expr::Code(block) => self.get_block_info(block.iter(), token),
             Expr::ReDef(redef) => self.get_redef_info(redef, token),
             Expr::Import(_) => None,
         }
@@ -690,7 +696,7 @@ impl<'a> HIRVisitor<'a> {
 
     fn get_def_info(&self, def: &Def, token: &Token) -> Option<VarInfo> {
         self.get_sig_info(&def.sig, token)
-            .or_else(|| self.get_block_info(&def.body.block, token))
+            .or_else(|| self.get_block_info(def.body.block.iter(), token))
     }
 
     fn get_class_def_info(&self, class_def: &ClassDef, token: &Token) -> Option<VarInfo> {
@@ -699,17 +705,21 @@ impl<'a> HIRVisitor<'a> {
             .as_ref()
             .and_then(|req_sup| self.get_expr_info(req_sup, token))
             .or_else(|| self.get_sig_info(&class_def.sig, token))
-            .or_else(|| self.get_block_info(&class_def.methods, token))
+            .or_else(|| self.get_block_info(class_def.all_methods(), token))
     }
 
     fn get_patch_def_info(&self, patch_def: &PatchDef, token: &Token) -> Option<VarInfo> {
         self.get_expr_info(&patch_def.base, token)
             .or_else(|| self.get_sig_info(&patch_def.sig, token))
-            .or_else(|| self.get_block_info(&patch_def.methods, token))
+            .or_else(|| self.get_block_info(patch_def.methods.iter(), token))
     }
 
-    fn get_block_info(&self, block: &Block, token: &Token) -> Option<VarInfo> {
-        for chunk in block.iter() {
+    fn get_block_info<'e>(
+        &self,
+        block: impl Iterator<Item = &'e Expr>,
+        token: &Token,
+    ) -> Option<VarInfo> {
+        for chunk in block {
             if let Some(expr) = self.get_expr_info(chunk, token) {
                 return Some(expr);
             }
@@ -719,7 +729,7 @@ impl<'a> HIRVisitor<'a> {
 
     fn get_redef_info(&self, redef: &ReDef, token: &Token) -> Option<VarInfo> {
         self.get_acc_info(&redef.attr, token)
-            .or_else(|| self.get_block_info(&redef.block, token))
+            .or_else(|| self.get_block_info(redef.block.iter(), token))
     }
 
     fn get_dummy_info(&self, dummy: &Dummy, token: &Token) -> Option<VarInfo> {
@@ -733,7 +743,7 @@ impl<'a> HIRVisitor<'a> {
 
     fn get_lambda_info(&self, lambda: &Lambda, token: &Token) -> Option<VarInfo> {
         self.get_params_info(&lambda.params, token)
-            .or_else(|| self.get_block_info(&lambda.body, token))
+            .or_else(|| self.get_block_info(lambda.body.iter(), token))
     }
 
     fn get_array_info(&self, arr: &Array, token: &Token) -> Option<VarInfo> {
diff --git a/crates/els/inlay_hint.rs b/crates/els/inlay_hint.rs
index 54907c9d0..75d98ad96 100644
--- a/crates/els/inlay_hint.rs
+++ b/crates/els/inlay_hint.rs
@@ -227,8 +227,7 @@ impl<'s, C: BuildRunnable, P: Parsable> InlayHintGenerator<'s, C, P> {
 
     fn get_class_def_hint(&self, class_def: &ClassDef) -> Vec<InlayHint> {
         class_def
-            .methods
-            .iter()
+            .all_methods()
             .flat_map(|expr| self.get_expr_hint(expr))
             .collect()
     }
diff --git a/crates/els/symbol.rs b/crates/els/symbol.rs
index 8800882e2..bd5658660 100644
--- a/crates/els/symbol.rs
+++ b/crates/els/symbol.rs
@@ -163,7 +163,7 @@ impl<Checker: BuildRunnable, Parser: Parsable> Server<Checker, Parser> {
                         res.extend(symbol);
                     }
                 }
-                for method in def.methods.iter() {
+                for method in def.all_methods() {
                     let symbol = self.symbol(method);
                     res.extend(symbol);
                 }
diff --git a/crates/erg_compiler/codegen.rs b/crates/erg_compiler/codegen.rs
index 4289e2dcb..32bb8f890 100644
--- a/crates/erg_compiler/codegen.rs
+++ b/crates/erg_compiler/codegen.rs
@@ -3339,7 +3339,7 @@ impl PyCodeGenerator {
         log!(info "entered {}", fn_name!());
         let name = class.sig.ident().inspect().clone();
         self.unit_size += 1;
-        let firstlineno = match class.methods.get(0).and_then(|def| def.ln_begin()) {
+        let firstlineno = match class.methods_list.get(0).and_then(|def| def.ln_begin()) {
             Some(l) => l,
             None => class.sig.ln_begin().unwrap_or(0),
         };
@@ -3362,8 +3362,9 @@ impl PyCodeGenerator {
         if class.need_to_gen_new {
             self.emit_new_func(&class.sig, class.__new__);
         }
-        if !class.methods.is_empty() {
-            self.emit_simple_block(class.methods);
+        let methods = ClassDef::take_all_methods(class.methods_list);
+        if !methods.is_empty() {
+            self.emit_simple_block(methods);
         }
         if self.stack_len() == init_stack_len {
             self.emit_load_const(ValueObj::None);
diff --git a/crates/erg_compiler/context/generalize.rs b/crates/erg_compiler/context/generalize.rs
index 156cb668d..94414de1f 100644
--- a/crates/erg_compiler/context/generalize.rs
+++ b/crates/erg_compiler/context/generalize.rs
@@ -1295,7 +1295,7 @@ impl Context {
                 }
             }
             hir::Expr::ClassDef(class_def) => {
-                for def in class_def.methods.iter_mut() {
+                for def in class_def.all_methods_mut() {
                     self.resolve_expr_t(def, qnames)?;
                 }
                 Ok(())
diff --git a/crates/erg_compiler/context/inquire.rs b/crates/erg_compiler/context/inquire.rs
index 577a458cb..85fca9bff 100644
--- a/crates/erg_compiler/context/inquire.rs
+++ b/crates/erg_compiler/context/inquire.rs
@@ -3405,7 +3405,7 @@ impl Context {
         candidates.collect()
     }
 
-    pub(crate) fn is_class(&self, typ: &Type) -> bool {
+    pub fn is_class(&self, typ: &Type) -> bool {
         match typ {
             Type::And(_l, _r) => false,
             Type::Never => true,
@@ -3429,7 +3429,7 @@ impl Context {
         }
     }
 
-    pub(crate) fn is_trait(&self, typ: &Type) -> bool {
+    pub fn is_trait(&self, typ: &Type) -> bool {
         match typ {
             Type::Never => false,
             Type::FreeVar(fv) if fv.is_linked() => self.is_class(&fv.crack()),
diff --git a/crates/erg_compiler/desugar_hir.rs b/crates/erg_compiler/desugar_hir.rs
index 443eb8f23..60cb36106 100644
--- a/crates/erg_compiler/desugar_hir.rs
+++ b/crates/erg_compiler/desugar_hir.rs
@@ -41,22 +41,22 @@ impl HIRDesugarer {
         match chunk {
             Expr::ClassDef(class_def) => {
                 let class = Expr::Accessor(Accessor::Ident(class_def.sig.ident().clone()));
-                let methods = std::mem::take(class_def.methods.ref_mut_payload());
-                let (methods, static_members): (Vec<_>, Vec<_>) = methods
-                    .into_iter()
-                    .partition(|attr| matches!(attr, Expr::Def(def) if def.sig.is_subr()));
-                class_def.methods.extend(methods);
-                let static_members = static_members
-                    .into_iter()
-                    .map(|expr| match expr {
+                let mut static_members = vec![];
+                for methods_ in class_def.methods_list.iter_mut() {
+                    let block = std::mem::take(&mut methods_.defs);
+                    let (methods, statics): (Vec<_>, Vec<_>) = block
+                        .into_iter()
+                        .partition(|attr| matches!(attr, Expr::Def(def) if def.sig.is_subr()));
+                    methods_.defs.extend(methods);
+                    static_members.extend(statics.into_iter().map(|expr| match expr {
                         Expr::Def(def) => {
                             let acc = class.clone().attr(def.sig.into_ident());
                             let redef = ReDef::new(acc, def.body.block);
                             Expr::ReDef(redef)
                         }
                         _ => expr,
-                    })
-                    .collect::<Vec<_>>();
+                    }));
+                }
                 if !static_members.is_empty() {
                     *chunk = Expr::Compound(Block::new(
                         [vec![std::mem::take(chunk)], static_members].concat(),
diff --git a/crates/erg_compiler/effectcheck.rs b/crates/erg_compiler/effectcheck.rs
index bdfaf27dd..20808305f 100644
--- a/crates/erg_compiler/effectcheck.rs
+++ b/crates/erg_compiler/effectcheck.rs
@@ -95,7 +95,7 @@ impl SideEffectChecker {
                         self.check_expr(req_sup);
                     }
                     // TODO: grow
-                    for def in class_def.methods.iter() {
+                    for def in class_def.all_methods() {
                         self.check_expr(def);
                     }
                 }
@@ -324,7 +324,7 @@ impl SideEffectChecker {
                 if let Some(req_sup) = &class_def.require_or_sup {
                     self.check_expr(req_sup);
                 }
-                for def in class_def.methods.iter() {
+                for def in class_def.all_methods() {
                     self.check_expr(def);
                 }
             }
diff --git a/crates/erg_compiler/hir.rs b/crates/erg_compiler/hir.rs
index aa1afc55f..481fb330f 100644
--- a/crates/erg_compiler/hir.rs
+++ b/crates/erg_compiler/hir.rs
@@ -2301,14 +2301,19 @@ impl Def {
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Methods {
-    pub class: TypeSpec,
-    pub vis: Token,        // `.` or `::`
-    pub defs: RecordAttrs, // TODO: allow declaration
+    pub class: Type,
+    pub impl_trait: Option<Type>,
+    pub defs: Block,
 }
 
 impl NestedDisplay for Methods {
     fn fmt_nest(&self, f: &mut fmt::Formatter<'_>, level: usize) -> fmt::Result {
-        writeln!(f, "{}{}", self.class, self.vis.content)?;
+        writeln!(
+            f,
+            "{} {}",
+            self.class,
+            fmt_option!("|<: ", &self.impl_trait, "|"),
+        )?;
         self.defs.fmt_nest(f, level + 1)
     }
 }
@@ -2317,16 +2322,16 @@ impl NestedDisplay for Methods {
 impl NoTypeDisplay for Methods {
     fn to_string_notype(&self) -> String {
         format!(
-            "{}{} {}",
+            "{} {} {}",
             self.class,
-            self.vis.content,
+            fmt_option!("|<: ", &self.impl_trait, "|"),
             self.defs.to_string_notype()
         )
     }
 }
 
 impl_display_from_nested!(Methods);
-impl_locational!(Methods, class, defs);
+impl_locational!(Methods, defs);
 
 impl HasType for Methods {
     #[inline]
@@ -2348,8 +2353,12 @@ impl HasType for Methods {
 }
 
 impl Methods {
-    pub const fn new(class: TypeSpec, vis: Token, defs: RecordAttrs) -> Self {
-        Self { class, vis, defs }
+    pub const fn new(class: Type, impl_trait: Option<Type>, defs: Block) -> Self {
+        Self {
+            class,
+            impl_trait,
+            defs,
+        }
     }
 }
 
@@ -2361,26 +2370,32 @@ pub struct ClassDef {
     /// The type of `new` that is automatically defined if not defined
     pub need_to_gen_new: bool,
     pub __new__: Type,
-    pub methods: Block,
+    pub methods_list: Vec<Methods>,
 }
 
 impl NestedDisplay for ClassDef {
     fn fmt_nest(&self, f: &mut fmt::Formatter<'_>, level: usize) -> fmt::Result {
         self.sig.fmt_nest(f, level)?;
         writeln!(f, ":")?;
-        self.methods.fmt_nest(f, level + 1)
+        fmt_lines(self.methods_list.iter(), f, level)
     }
 }
 
 // TODO
 impl NoTypeDisplay for ClassDef {
     fn to_string_notype(&self) -> String {
-        format!("{}: {}", self.sig, self.methods.to_string_notype())
+        let methods = self
+            .methods_list
+            .iter()
+            .map(|m| m.to_string_notype())
+            .collect::<Vec<_>>()
+            .join("\n");
+        format!("{}: {methods}", self.sig)
     }
 }
 
 impl_display_from_nested!(ClassDef);
-impl_locational!(ClassDef, sig, lossy methods);
+impl_locational!(ClassDef, sig, lossy methods_list);
 
 impl HasType for ClassDef {
     #[inline]
@@ -2408,7 +2423,7 @@ impl ClassDef {
         require_or_sup: Option<Expr>,
         need_to_gen_new: bool,
         __new__: Type,
-        methods: Block,
+        methods_list: Vec<Methods>,
     ) -> Self {
         Self {
             obj,
@@ -2416,8 +2431,24 @@ impl ClassDef {
             require_or_sup: require_or_sup.map(Box::new),
             need_to_gen_new,
             __new__,
-            methods,
+            methods_list,
+        }
+    }
+
+    pub fn all_methods(&self) -> impl Iterator<Item = &Expr> {
+        self.methods_list.iter().flat_map(|m| m.defs.iter())
+    }
+
+    pub fn all_methods_mut(&mut self) -> impl Iterator<Item = &mut Expr> {
+        self.methods_list.iter_mut().flat_map(|m| m.defs.iter_mut())
+    }
+
+    pub fn take_all_methods(methods_list: Vec<Methods>) -> Block {
+        let mut joined = Block::empty();
+        for methods in methods_list {
+            joined.extend(methods.defs);
         }
+        joined
     }
 }
 
diff --git a/crates/erg_compiler/link_hir.rs b/crates/erg_compiler/link_hir.rs
index 6b90aeabf..441bedbac 100644
--- a/crates/erg_compiler/link_hir.rs
+++ b/crates/erg_compiler/link_hir.rs
@@ -197,7 +197,7 @@ impl<'a> HIRLinker<'a> {
                 }
             }
             Expr::ClassDef(class_def) => {
-                for def in class_def.methods.iter_mut() {
+                for def in class_def.all_methods_mut() {
                     Self::resolve_pymod_path(def);
                 }
             }
@@ -332,7 +332,7 @@ impl<'a> HIRLinker<'a> {
                 }
             }
             Expr::ClassDef(class_def) => {
-                for def in class_def.methods.iter_mut() {
+                for def in class_def.all_methods_mut() {
                     self.replace_import(def);
                 }
             }
diff --git a/crates/erg_compiler/lint.rs b/crates/erg_compiler/lint.rs
index e3e83e343..68ce7a595 100644
--- a/crates/erg_compiler/lint.rs
+++ b/crates/erg_compiler/lint.rs
@@ -122,7 +122,7 @@ impl<ASTBuilder: ASTBuildable> GenericASTLowerer<ASTBuilder> {
                 }
             }
             hir::Expr::ClassDef(class_def) => {
-                for chunk in class_def.methods.iter() {
+                for chunk in class_def.all_methods() {
                     if let Err(ws) = self.expr_use_check(chunk) {
                         warns.extend(ws);
                     }
@@ -233,7 +233,7 @@ impl<ASTBuilder: ASTBuildable> GenericASTLowerer<ASTBuilder> {
                 }
             }
             Expr::ClassDef(class_def) => {
-                for chunk in class_def.methods.iter() {
+                for chunk in class_def.all_methods() {
                     self.check_doc_comment(chunk);
                 }
             }
@@ -298,7 +298,7 @@ impl<ASTBuilder: ASTBuildable> GenericASTLowerer<ASTBuilder> {
     fn warn_implicit_union_chunk(&mut self, chunk: &Expr) {
         match chunk {
             Expr::ClassDef(class_def) => {
-                for chunk in class_def.methods.iter() {
+                for chunk in class_def.all_methods() {
                     self.warn_implicit_union_chunk(chunk);
                 }
             }
diff --git a/crates/erg_compiler/lower.rs b/crates/erg_compiler/lower.rs
index a57ceb9f2..6e77ce2d8 100644
--- a/crates/erg_compiler/lower.rs
+++ b/crates/erg_compiler/lower.rs
@@ -2097,8 +2097,9 @@ impl<A: ASTBuildable> GenericASTLowerer<A> {
     fn lower_class_def(&mut self, class_def: ast::ClassDef) -> LowerResult<hir::ClassDef> {
         log!(info "entered {}({class_def})", fn_name!());
         let mut hir_def = self.lower_def(class_def.def)?;
-        let mut hir_methods = hir::Block::empty();
+        let mut hir_methods_list = vec![];
         for methods in class_def.methods_list.into_iter() {
+            let mut hir_methods = hir::Block::empty();
             let (class, impl_trait) = self
                 .module
                 .context
@@ -2198,7 +2199,9 @@ impl<A: ASTBuildable> GenericASTLowerer<A> {
             if let Err(err) = self.check_trait_impl(impl_trait.clone(), &class) {
                 self.errs.push(err);
             }
-            self.check_collision_and_push(methods.id, class, impl_trait.map(|(t, _)| t));
+            let impl_trait = impl_trait.map(|(t, _)| t);
+            self.check_collision_and_push(methods.id, class.clone(), impl_trait.clone());
+            hir_methods_list.push(hir::Methods::new(class, impl_trait, hir_methods));
         }
         let class = self.module.context.gen_type(&hir_def.sig.ident().raw);
         let Some(class_ctx) = self.module.context.get_nominal_type_ctx(&class) else {
@@ -2242,7 +2245,7 @@ impl<A: ASTBuildable> GenericASTLowerer<A> {
             require_or_sup,
             need_to_gen_new,
             __new__.t.clone(),
-            hir_methods,
+            hir_methods_list,
         ))
     }
 
diff --git a/crates/erg_compiler/ownercheck.rs b/crates/erg_compiler/ownercheck.rs
index 393ae4e1c..6e7019775 100644
--- a/crates/erg_compiler/ownercheck.rs
+++ b/crates/erg_compiler/ownercheck.rs
@@ -131,7 +131,7 @@ impl OwnershipChecker {
                 if let Some(req_sup) = &class_def.require_or_sup {
                     self.check_expr(req_sup, Ownership::Owned, false);
                 }
-                for def in class_def.methods.iter() {
+                for def in class_def.all_methods() {
                     self.check_expr(def, Ownership::Owned, true);
                 }
             }
diff --git a/crates/erg_compiler/transpile.rs b/crates/erg_compiler/transpile.rs
index ee390c3bd..24b496a40 100644
--- a/crates/erg_compiler/transpile.rs
+++ b/crates/erg_compiler/transpile.rs
@@ -1112,7 +1112,8 @@ impl PyScriptGenerator {
             code += &"    ".repeat(self.level + 1);
             code += &format!("def new(x): return {class_name}.__call__(x)\n");
         }
-        code += &self.transpile_block(classdef.methods, Discard);
+        let methods = ClassDef::take_all_methods(classdef.methods_list);
+        code += &self.transpile_block(methods, Discard);
         code
     }