Rlp2Core: pattern let binds

src/Control/Monad/Utils.hs

@@ -1,10 +1,13 @@
 module Control.Monad.Utils
     ( mapAccumLM
+    , Kendo(..)
     )
     where
 ----------------------------------------------------------------------------------
 import Data.Tuple               (swap)
+import Data.Coerce
 import Control.Monad.State
+import Control.Monad
 ----------------------------------------------------------------------------------
 
 -- | Monadic variant of @mapAccumL@
@@ -19,3 +22,11 @@ mapAccumLM k s t = swap <$> runStateT (traverse k' t) s
         k' :: a -> StateT s m b
         k' a = StateT $ fmap swap <$> flip k a
 
+newtype Kendo m a = Kendo { appKendo :: a -> m a }
+
+instance (Monad m) => Semigroup (Kendo m a) where
+    Kendo f <> Kendo g = Kendo (f <=< g)
+
+instance (Monad m) => Monoid (Kendo m a) where
+    mempty = Kendo pure
+