diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,11 @@
 # Changelog for homotuple
 
+## 0.1.2.1
+
+2020.06.13
+
+0.1.2.0 cannot be built.
+
 ## 0.1.2.0
 
 2020.06.13
diff --git a/homotuple.cabal b/homotuple.cabal
--- a/homotuple.cabal
+++ b/homotuple.cabal
@@ -1,7 +1,7 @@
 cabal-version: 1.12
 
 name:           homotuple
-version:        0.1.2.0
+version:        0.1.2.1
 synopsis:       Homotuple, all whose elements are the same type
 description:    Homotuple, all whose elements are the same type
 category:       Data
@@ -17,6 +17,8 @@
 extra-source-files:
     README.md
     ChangeLog.md
+    template/Homotuple.hs
+    template/HomotupleItem.hs
 
 source-repository head
   type: git
diff --git a/template/Homotuple.hs b/template/Homotuple.hs
new file mode 100644
--- /dev/null
+++ b/template/Homotuple.hs
@@ -0,0 +1,267 @@
+{-# LANGUAGE ConstraintKinds        #-}
+{-# LANGUAGE DataKinds              #-}
+{-# LANGUAGE FlexibleContexts       #-}
+{-# LANGUAGE FlexibleInstances      #-}
+{-# LANGUAGE PatternSynonyms        #-}
+{-# LANGUAGE ScopedTypeVariables    #-}
+{-# LANGUAGE Trustworthy            #-}
+{-# LANGUAGE TypeFamilies           #-}
+{-# LANGUAGE TypeFamilyDependencies #-}
+{-# LANGUAGE TypeOperators          #-}
+
+{-# OPTIONS_GHC -Wno-orphans #-}
+
+{-# OPTIONS_HADDOCK show-extensions #-}
+
+-- |
+-- Copyright   :  Kazuki Okamoto
+-- License     :  see LICENSE
+-- Maintainer  :  kazuki.okamoto@kakkun61.com
+-- Stability   :  experimental
+-- Portability :  GHC
+--
+-- Homotuples, whoes items are the same type or which are lists with type-level length.
+
+module Data.Tuple.Homotuple
+  ( Homotuple
+    -- * List-like
+  , replicate
+    -- * Functor-like
+  , (<$>)
+    -- * Applicative-like
+  , (<*>)
+  , pure
+    -- * Monad-like
+  , (>>=)
+    -- * Semigoupe-like
+  , (<>)
+    -- * Monoid-like
+  , pattern Empty
+    -- * Utility constraints
+  , IsHomolisttuple
+  , IsHomotupleItem
+    -- * For implementers
+  , errorLengthMismatch
+  ) where
+
+import Prelude (Num (fromInteger), error, ($), (.))
+
+import qualified Control.Applicative as A
+import qualified Control.Monad       as M
+import           Data.Kind           (Type)
+import qualified Data.List           as L
+import           Data.Proxy          (Proxy (Proxy))
+import qualified Data.Semigroup      as S
+import           Data.Tuple.Single   (Single (wrap))
+import           GHC.Exts            (IsList (Item, fromList, toList))
+import           GHC.Stack           (HasCallStack)
+import           GHC.TypeLits        (type (*), type (+), KnownNat, Nat, natVal)
+
+type family Homotuple (n :: Nat) (a :: Type) = (t :: Type) | t -> n
+
+-- 0
+
+type instance Homotuple 0 a = Proxy a
+
+instance IsList (Proxy a) where
+  type Item (Proxy a) = a
+  fromList [] = Proxy
+  fromList _  = errorLengthMismatch
+  toList _ = []
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+errorLengthMismatch :: HasCallStack => a
+errorLengthMismatch = error "length mismatch"
+
+-- Utility constraints
+
+type IsHomolisttuple (n :: Nat) a = IsList (Homotuple n a)
+type IsHomotupleItem (n :: Nat) a = a ~ Item (Homotuple n a)
+
+-- List-like
+
+replicate :: forall (n :: Nat) a. (IsHomolisttuple n a, IsHomotupleItem n a, KnownNat n) => a -> Homotuple n a
+replicate = fromList . L.replicate (fromInteger $ natVal (Proxy :: Proxy n))
+
+-- Functor-like
+
+(<$>)
+  :: ( IsHomolisttuple n a
+     , IsHomolisttuple n b
+     , IsHomotupleItem n a
+     , IsHomotupleItem n b
+     )
+  => (a -> b) -> Homotuple n a -> Homotuple n b
+f <$> t = fromList $ L.map f $ toList t
+
+-- Applicative-like
+
+(<*>)
+  :: ( IsHomolisttuple n0 (a -> b)
+     , IsHomolisttuple n1 a
+     , IsHomolisttuple (n0 * n1) b
+     , IsHomotupleItem n0 (a -> b)
+     , IsHomotupleItem n1 a
+     , IsHomotupleItem (n0 * n1) b
+     )
+  => Homotuple n0 (a -> b) -> Homotuple n1 a -> Homotuple (n0 * n1) b
+f <*> t = fromList $ toList f A.<*> toList t
+
+pure :: Single c => a -> c a
+pure = wrap
+
+-- Monad-like
+
+(>>=)
+  :: ( IsHomolisttuple n0 a
+     , IsHomolisttuple n1 b
+     , IsHomolisttuple (n0 * n1) b
+     , IsHomotupleItem n0 a
+     , IsHomotupleItem n1 b
+     , IsHomotupleItem (n0 * n1) b
+     )
+  => Homotuple n0 a -> (a -> Homotuple n1 b) -> Homotuple (n0 * n1) b
+m >>= f = fromList $ toList m M.>>= (toList . f)
+
+-- Semigroup-like
+
+(<>)
+  :: ( IsHomolisttuple n0 a
+     , IsHomolisttuple n1 a
+     , IsHomolisttuple (n0 + n1) a
+     , IsHomotupleItem n0 a
+     , IsHomotupleItem n1 a
+     , IsHomotupleItem (n0 + n1) a
+     )
+  => Homotuple n0 a
+  -> Homotuple n1 a
+  -> Homotuple (n0 + n1) a
+a <> b = fromList $ toList a S.<> toList b
+
+infixr 6 <>
+
+-- Monoid-like
+
+pattern Empty :: Homotuple 0 a
+pattern Empty = Proxy
diff --git a/template/HomotupleItem.hs b/template/HomotupleItem.hs
new file mode 100644
--- /dev/null
+++ b/template/HomotupleItem.hs
@@ -0,0 +1,9 @@
+-- <length>
+
+type instance Homotuple <length> a = <homotuple>
+
+instance IsList <homotuple> where
+  type Item <homotuple> = a
+  fromList <list> = <tuple>
+  fromList _ = errorLengthMismatch
+  toList <tuple> = <list>