diff --git a/src/obj/boolean.rs b/src/obj/boolean.rs
index 99ae3a9..79fc36c 100644
--- a/src/obj/boolean.rs
+++ b/src/obj/boolean.rs
@@ -51,7 +51,7 @@ pub static BOOL_TRUE: Lazy<BoolRef> = Lazy::new(||
             attrs: Default::default(),
         },
         vtable: |obj_ref: ObjRef| vtable! {
-            BOOL_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), BOOL_BOOL_FUN.clone()),
+            BOOL_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), BOOL_BOOL_METH.clone()),
         }
     }
 );
@@ -67,7 +67,7 @@ pub static BOOL_FALSE: Lazy<BoolRef> = Lazy::new(||
             attrs: Default::default(),
         },
         vtable: |obj_ref: ObjRef| vtable! {
-            BOOL_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), BOOL_BOOL_FUN.clone()),
+            BOOL_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), BOOL_BOOL_METH.clone()),
         }
     }
 );
@@ -77,7 +77,7 @@ pub static BOOL_FALSE: Lazy<BoolRef> = Lazy::new(||
 ////////////////////////////////////////////////////////////////////////////////
 
 /// Bool.__bool__(self) impl
-static BOOL_BOOL_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static BOOL_BOOL_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(1, |_callee, vm, args| {
         {
             read_obj_downcast!(let value: Option<&Bool> = &args[0]);
diff --git a/src/obj/builtin.rs b/src/obj/builtin.rs
index 7e8e12c..5a4edc2 100644
--- a/src/obj/builtin.rs
+++ b/src/obj/builtin.rs
@@ -1,3 +1,5 @@
+//! Builtin objects and functions.
+
 use crate::{
     obj::{prelude::*, reserved::*},
     vm::{error::*, signal::*},
@@ -6,6 +8,10 @@ use maplit::btreemap;
 use once_cell::sync::Lazy;
 use std::collections::BTreeMap;
 
+////////////////////////////////////////////////////////////////////////////////
+// Builtin free functions
+////////////////////////////////////////////////////////////////////////////////
+
 pub static PRINTLN_BUILTIN_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(1, |_, vm, args| {
         // TODO : use __get_attr__ when it gets added
@@ -64,6 +70,10 @@ pub static PRINT_BUILTIN_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
     })
 });
 
+////////////////////////////////////////////////////////////////////////////////
+// Builtin objects
+////////////////////////////////////////////////////////////////////////////////
+
 pub static BUILTIN_OBJS: Lazy<BTreeMap<Sym, ObjRef>> = Lazy::new(|| {
     btreemap! {
         PRINTLN_BUILTIN_NAME.sym => PRINTLN_BUILTIN_FUN.clone() as _,
diff --git a/src/obj/int.rs b/src/obj/int.rs
index de92d55..5a29d92 100644
--- a/src/obj/int.rs
+++ b/src/obj/int.rs
@@ -26,16 +26,16 @@ impl Int {
                 attrs: Default::default(),
             },
             vtable: |obj_ref: ObjRef| vtable! {
-                BOOL_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), INT_BOOL_FUN.clone()),
-                REPR_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), INT_STR_FUN.clone()),
-                STR_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), INT_STR_FUN.clone()),
-                INT_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), INT_INT_FUN.clone()),
-                PLUS_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_ADD_FUN.clone()),
-                MINUS_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_SUB_FUN.clone()),
-                TIMES_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_MUL_FUN.clone()),
-                DIV_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_DIV_FUN.clone()),
-                EQ_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_EQ_FUN.clone()),
-                NE_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_NE_FUN.clone()),
+                BOOL_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), INT_BOOL_METH.clone()),
+                REPR_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), INT_STR_METH.clone()),
+                STR_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), INT_STR_METH.clone()),
+                INT_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), INT_INT_METH.clone()),
+                PLUS_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_ADD_METH.clone()),
+                MINUS_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_SUB_METH.clone()),
+                TIMES_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_MUL_METH.clone()),
+                DIV_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_DIV_METH.clone()),
+                EQ_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_EQ_METH.clone()),
+                NE_OP_NAME.sym => Method::new_obj(obj_ref.clone(), INT_NE_METH.clone()),
             }
         }
     }
@@ -58,7 +58,7 @@ impl Debug for Int {
 ////////////////////////////////////////////////////////////////////////////////
 
 /// Int.__bool__(self) impl
-static INT_BOOL_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static INT_BOOL_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(1, |_callee, vm, args| {
         read_obj_downcast!(let int_obj: Option<&Int> = &args[0]);
         let int_obj = int_obj.ok_or_else(|| Error::ValueError {
@@ -70,7 +70,7 @@ static INT_BOOL_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
 });
 
 /// Int.__str__(self) impl
-static INT_STR_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static INT_STR_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(1, |_callee, vm, args| {
         read_obj_downcast!(let int_obj: Option<&Int> = &args[0]);
         let int_obj = int_obj.ok_or_else(|| Error::ValueError {
@@ -82,7 +82,7 @@ static INT_STR_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
 });
 
 /// Int.__int__(self) impl
-static INT_INT_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static INT_INT_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(1, |_callee, vm, args| {
         {
             read_obj_downcast!(let int_obj: Option<&Int> = &args[0]);
@@ -98,7 +98,7 @@ static INT_INT_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
 });
 
 /// Int.__add__(self, Int) impl
-static INT_ADD_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static INT_ADD_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(2, |_callee, vm, args| {
         read_obj_downcast!(let lhs: Option<&Int> = &args[0]);
         let lhs = lhs.ok_or_else(|| Error::ValueError {
@@ -117,7 +117,7 @@ static INT_ADD_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
 });
 
 /// Int.__sub__(self, Int) impl
-static INT_SUB_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static INT_SUB_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(2, |_callee, vm, args| {
         read_obj_downcast!(let lhs: Option<&Int> = &args[0]);
         let lhs = lhs.ok_or_else(|| Error::ValueError {
@@ -136,7 +136,7 @@ static INT_SUB_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
 });
 
 /// Int.__mul__(self, Int) impl
-static INT_MUL_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static INT_MUL_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(2, |_callee, vm, args| {
         read_obj_downcast!(let lhs: Option<&Int> = &args[0]);
         let lhs = lhs.ok_or_else(|| Error::ValueError {
@@ -155,7 +155,7 @@ static INT_MUL_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
 });
 
 /// Int.__div__(self, Int) impl
-static INT_DIV_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static INT_DIV_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(2, |_callee, vm, args| {
         read_obj_downcast!(let lhs: Option<&Int> = &args[0]);
         let lhs = lhs.ok_or_else(|| Error::ValueError {
@@ -174,7 +174,7 @@ static INT_DIV_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
 });
 
 /// Int.__eq__(self, Int) impl
-static INT_EQ_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static INT_EQ_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(2, |_callee, vm, args| {
         read_obj_downcast!(let lhs: Option<&Int> = &args[0]);
         let lhs = lhs.ok_or_else(|| Error::ValueError {
@@ -193,7 +193,7 @@ static INT_EQ_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
 });
 
 /// Int.__ne__(self, Int) impl
-static INT_NE_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static INT_NE_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(2, |_callee, vm, args| {
         read_obj_downcast!(let lhs: Option<&Int> = &args[0]);
         let lhs = lhs.ok_or_else(|| Error::ValueError {
diff --git a/src/obj/mod.rs b/src/obj/mod.rs
index 61bd8c8..fc12b18 100644
--- a/src/obj/mod.rs
+++ b/src/obj/mod.rs
@@ -66,8 +66,6 @@ pub trait Obj: Scan + GcDrop + Debug {
     obj_attr!(get_ty, TY_MEMBER_NAME);
     obj_attr!(get_call, CALL_MEMBER_NAME);
     obj_attr!(get_name, NAME_MEMBER_NAME);
-    //obj_attr!(get_get_attr, GET_ATTR_NAME);
-    //obj_attr!(get_set_attr, SET_ATTR_NAME);
     obj_attr!(get_self, SELF_MEMBER_NAME);
     obj_attr!(get_func, FUNC_MEMBER_NAME);
     obj_attr!(get_eq, EQ_OP_NAME);
diff --git a/src/obj/str.rs b/src/obj/str.rs
index bfd727b..d9ef33a 100644
--- a/src/obj/str.rs
+++ b/src/obj/str.rs
@@ -24,9 +24,9 @@ impl Str {
                 attrs: Default::default(),
             },
             vtable: |obj_ref: ObjRef| vtable! {
-                STR_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), STR_STR_FUN.clone()),
-                REPR_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), STR_REPR_FUN.clone()),
-                INT_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), STR_INT_FUN.clone()),
+                STR_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), STR_STR_METH.clone()),
+                REPR_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), STR_REPR_METH.clone()),
+                INT_MEMBER_NAME.sym => Method::new_obj(obj_ref.clone(), STR_INT_METH.clone()),
             },
         }
     }
@@ -49,7 +49,7 @@ impl Debug for Str {
 ////////////////////////////////////////////////////////////////////////////////
 
 /// Str.__str__(self) impl
-static STR_STR_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static STR_STR_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(1, |_callee, vm, args| {
         {
             read_obj_downcast!(let str_obj: Option<&Str> = &args[0]);
@@ -65,7 +65,7 @@ static STR_STR_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
 });
 
 /// Str.__repr__(self) impl
-static STR_REPR_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static STR_REPR_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(1, |_callee, vm, args| {
         read_obj_downcast!(let str_obj: Option<&Str> = &args[0]);
         let str_obj = str_obj.ok_or_else(|| Error::ValueError {
@@ -80,7 +80,7 @@ static STR_REPR_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
 });
 
 /// Str.__int__(self) impl
-static STR_INT_FUN: Lazy<NativeFunRef> = Lazy::new(|| {
+static STR_INT_METH: Lazy<NativeFunRef> = Lazy::new(|| {
     NativeFun::new_obj(1, |_callee, vm, args| {
         read_obj_downcast!(let str_obj: Option<&Str> = &args[0]);
         let str_obj = str_obj.ok_or_else(|| Error::ValueError {