diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,12 @@
 # Revision history for monadic-recursion-schemes
 
+## 0.1.4.2 -- 2020-05-14
+
+* add comment.
+
 ## 0.1.4.1 -- 2020-05-14
 
-* add alternative for dynaM and codynaM
+* add alternative for dynaM and codynaM.
 
 ## 0.1.4.0 -- 2020-05-14
 
diff --git a/monadic-recursion-schemes.cabal b/monadic-recursion-schemes.cabal
--- a/monadic-recursion-schemes.cabal
+++ b/monadic-recursion-schemes.cabal
@@ -4,7 +4,7 @@
 -- http://haskell.org/cabal/users-guide/
 
 name:                monadic-recursion-schemes
-version:             0.1.4.1
+version:             0.1.4.2
 synopsis:            Recursion Schemes for Monadic version.
 description:         Yet another recursion schemes for monadic style, depends on recursion-schemes.
 homepage:            https://github.com/cutsea110/monadic-recursion-schemes.git
diff --git a/src/Data/Functor/Foldable/Monadic.hs b/src/Data/Functor/Foldable/Monadic.hs
--- a/src/Data/Functor/Foldable/Monadic.hs
+++ b/src/Data/Functor/Foldable/Monadic.hs
@@ -185,6 +185,7 @@
 dynaM'' phi psi = return . extract <=< hyloM f psi
   where f = liftM2 (:<) <$> phi <*> return
 
+-- | codynamorphism on recursive variant over chronomorphism
 codynaM :: (Monad m, Traversable t)
         => (t b -> m b)            -- ^ algebra
         -> (a -> m (t (Free t a))) -- ^ coalgebra
@@ -198,6 +199,7 @@
          -> t -> m c
 codynaM' phi psi = anaM psi <=< histoM phi
 
+-- | codynamorphism on recursive variant over hylomorphism
 codynaM'' :: (Monad m, Traversable t)
           => (t b -> m b)            -- ^ algebra
           -> (a -> m (t (Free t a))) -- ^ coalgebra