diff --git a/builtin/string.sk b/builtin/string.sk
index 9ee38359..37aafb90 100644
--- a/builtin/string.sk
+++ b/builtin/string.sk
@@ -54,6 +54,10 @@ class String
     ret
   end
 
+  # Returns list of characters (more specifically,
+  # grapheme clusters).
+  #def chars -> Array<String>
+
   # Call `f` for each byte
   def each_byte(f: Fn1<Int, Void>) 
     @bytesize.times do |i|
diff --git a/lib/skc_rustlib/src/builtin/array.rs b/lib/skc_rustlib/src/builtin/array.rs
index e388a6fb..770c54c8 100644
--- a/lib/skc_rustlib/src/builtin/array.rs
+++ b/lib/skc_rustlib/src/builtin/array.rs
@@ -1,6 +1,13 @@
-use crate::builtin::{SkInt, SkObj};
-use crate::sk_methods::meta_array_new;
-use shiika_ffi_macro::shiika_method;
+use crate::builtin::{SkClass, SkInt, SkObj};
+use crate::sk_cls::SkCls;
+use shiika_ffi_macro::{shiika_const_ref, shiika_method, shiika_method_ref};
+
+shiika_const_ref!("::Array", SkClass, "sk_Array");
+shiika_method_ref!(
+    "Meta:Array#new",
+    fn(receiver: SkClass) -> SkAry<SkObj>,
+    "meta_array_new"
+);
 
 #[repr(C)]
 #[derive(Debug)]
@@ -16,8 +23,9 @@ struct ShiikaArray<T> {
 
 impl<T> SkAry<T> {
     /// Call `Array.new`.
-    pub fn new<U>() -> SkAry<U> {
-        let sk_ary = meta_array_new(std::ptr::null());
+    pub fn new<U: SkCls>() -> SkAry<U> {
+        let spe_cls = sk_Array().specialize(vec![U::get_class_object()]);
+        let sk_ary = meta_array_new(spe_cls);
         // Force cast because external function (Meta_Array_new)
         // cannot have type a parameter.
         SkAry(sk_ary.0 as *mut ShiikaArray<U>)
diff --git a/lib/skc_rustlib/src/builtin/class.rs b/lib/skc_rustlib/src/builtin/class.rs
index 6a277502..98383ee8 100644
--- a/lib/skc_rustlib/src/builtin/class.rs
+++ b/lib/skc_rustlib/src/builtin/class.rs
@@ -2,9 +2,15 @@
 mod witness_table;
 use crate::builtin::class::witness_table::WitnessTable;
 use crate::builtin::{SkAry, SkInt, SkStr};
-use crate::sk_methods::meta_class_new;
-use shiika_ffi_macro::shiika_method;
+use shiika_ffi_macro::{shiika_method, shiika_method_ref};
 use std::collections::HashMap;
+
+shiika_method_ref!(
+    "Meta:Class#new",
+    fn(receiver: *const u8) -> SkClass,
+    "meta_class_new"
+);
+
 #[repr(C)]
 #[derive(Debug)]
 pub struct SkClass(*mut ShiikaClass);
@@ -31,6 +37,10 @@ impl SkClass {
         unsafe { &(*self.0).name }
     }
 
+    pub fn specialize(self, tyargs: Vec<SkClass>) -> SkClass {
+        class_specialize(self, tyargs)
+    }
+
     fn specialized_classes(&mut self) -> &mut HashMap<String, *mut ShiikaClass> {
         unsafe { (*self.0).specialized_classes.as_mut().unwrap() }
     }
diff --git a/lib/skc_rustlib/src/builtin/string.rs b/lib/skc_rustlib/src/builtin/string.rs
index 4bc3b8cb..32c32e2e 100644
--- a/lib/skc_rustlib/src/builtin/string.rs
+++ b/lib/skc_rustlib/src/builtin/string.rs
@@ -1,10 +1,18 @@
 //! Instance of `::String`
 use crate::builtin::object::ShiikaObject;
-use crate::builtin::{SkAry, SkInt, SkObj, SkPtr};
-use shiika_ffi_macro::shiika_method;
+use crate::builtin::{SkAry, SkClass, SkInt, SkObj, SkPtr};
+use crate::sk_cls::SkCls;
+use shiika_ffi_macro::{shiika_const_ref, shiika_method};
 use std::ffi::CString;
 use unicode_segmentation::UnicodeSegmentation;
 
+shiika_const_ref!("::String", SkClass, "sk_String");
+impl SkCls for SkStr {
+    fn get_class_object() -> SkClass {
+        sk_String()
+    }
+}
+
 extern "C" {
     // TODO: better name
     fn gen_literal_string(p: *const u8, bytesize: i64) -> SkStr;
diff --git a/lib/skc_rustlib/src/lib.rs b/lib/skc_rustlib/src/lib.rs
index 33c0b26f..cc89a90a 100644
--- a/lib/skc_rustlib/src/lib.rs
+++ b/lib/skc_rustlib/src/lib.rs
@@ -1,3 +1,4 @@
 mod allocator;
 mod builtin;
+mod sk_cls;
 mod sk_methods;
diff --git a/lib/skc_rustlib/src/sk_cls.rs b/lib/skc_rustlib/src/sk_cls.rs
new file mode 100644
index 00000000..f8f2a920
--- /dev/null
+++ b/lib/skc_rustlib/src/sk_cls.rs
@@ -0,0 +1,5 @@
+use crate::builtin::SkClass;
+
+pub trait SkCls {
+    fn get_class_object() -> SkClass;
+}