Add remaining instances for Comonad transformers (#145)

Author: skeate

CHANGELOG.md

@@ -7,6 +7,7 @@ Notable changes to this project are documented in this file. The format is based
 Breaking changes:
 
 New features:
+- Add `ComonadAsk`, `ComonadEnv`, and `ComonadTraced` instances for `StoreT`, `EnvT`, and `TracedT` (#145 by @skeate)
 
 Bugfixes:
 

src/Control/Comonad/Env/Class.purs

@@ -2,9 +2,13 @@
 
 module Control.Comonad.Env.Class where
 
+import Prelude
+
 import Control.Comonad (class Comonad)
 import Control.Comonad.Env.Trans (EnvT(..))
-
+import Control.Comonad.Store (StoreT(..))
+import Control.Comonad.Traced.Trans (TracedT(..))
+import Control.Comonad.Trans.Class (lower)
 import Data.Tuple (Tuple(..), fst)
 
 -- | The `ComonadEnv` type class represents those comonads which support a
@@ -44,3 +48,15 @@ instance comonadAskEnvT :: Comonad w => ComonadAsk e (EnvT e w) where
 instance comonadEnvEnvT :: Comonad w => ComonadEnv e (EnvT e w) where
   local f (EnvT x) = EnvT case x of
     Tuple y z -> Tuple (f y) z
+
+instance comonadAskTracedT :: (ComonadAsk e w, Monoid t) => ComonadAsk e (TracedT t w) where
+  ask = ask <<< lower
+
+instance comonadEnvTracedT :: (ComonadEnv e w, Monoid t) => ComonadEnv e (TracedT t w) where
+  local f (TracedT w) = TracedT (local f w)
+
+instance comonadAskStoreT :: ComonadAsk e w => ComonadAsk e (StoreT s w) where
+  ask = ask <<< lower
+
+instance comonadEnvStoreT :: ComonadEnv e w => ComonadEnv e (StoreT s w) where
+  local f (StoreT (Tuple w s)) = StoreT (Tuple (local f w) s) 

src/Control/Comonad/Traced/Class.purs

@@ -1,11 +1,22 @@
 -- | This module defines the `ComonadTraced` type class and its instances.
 
-module Control.Comonad.Traced.Class where
+module Control.Comonad.Traced.Class
+  ( class ComonadTraced
+  , track
+  , tracks
+  , listen
+  , listens
+  , censor
+  ) where
 
 import Prelude
 
 import Control.Comonad (class Comonad, extract)
+import Control.Comonad.Env (EnvT)
+import Control.Comonad.Store (StoreT)
 import Control.Comonad.Traced.Trans (TracedT(..))
+import Control.Comonad.Trans.Class (class ComonadTrans, lower)
+import Control.Monad.Identity.Trans (IdentityT)
 import Data.Tuple (Tuple(..))
 
 -- | The `ComonadTraced` type class represents those monads which support relative (monoidal)
@@ -47,3 +58,15 @@ censor f (TracedT tr) = TracedT ((f >>> _) <$> tr)
 
 instance comonadTracedTracedT :: (Comonad w, Monoid t) => ComonadTraced t (TracedT t w) where
   track t (TracedT tr) = extract tr t
+
+lowerTrack :: forall t m w a. ComonadTrans t => ComonadTraced m w => m -> t w a -> a
+lowerTrack m = track m <<< lower
+
+instance comonadTracedIdentityT :: ComonadTraced t w => ComonadTraced t (IdentityT w) where
+  track = lowerTrack
+
+instance comonadTracedEnvT :: ComonadTraced t w => ComonadTraced t (EnvT e w) where
+  track = lowerTrack
+
+instance comonadTracedStoreT :: ComonadTraced t w => ComonadTraced t (StoreT s w) where
+  track = lowerTrack

src/Control/Comonad/Trans/Class.purs

@@ -3,6 +3,7 @@
 module Control.Comonad.Trans.Class where
 
 import Control.Comonad (class Comonad)
+import Control.Monad.Identity.Trans (IdentityT, runIdentityT)
 
 -- | The `ComonadTrans` type class represents _comonad transformers_.
 -- |
@@ -21,3 +22,6 @@ import Control.Comonad (class Comonad)
 -- | - `lower (extend w (f <<< lower)) = extend (lower w) f`
 class ComonadTrans f where
   lower :: forall w a. Comonad w => f w a -> w a
+
+instance comonadTransIdentityT :: ComonadTrans IdentityT where
+  lower = runIdentityT

src/Control/Monad/Identity/Trans.purs

@@ -4,6 +4,7 @@ import Prelude
 
 import Control.Alt (class Alt)
 import Control.Alternative (class Alternative)
+import Control.Comonad (class Comonad, class Extend, extend, extract)
 import Control.Monad.Cont.Class (class MonadCont)
 import Control.Monad.Error.Class (class MonadError, class MonadThrow)
 import Control.Monad.Reader.Class (class MonadAsk, class MonadReader)
@@ -15,9 +16,9 @@ import Control.MonadPlus (class MonadPlus)
 import Control.Plus (class Plus)
 import Data.Eq (class Eq1)
 import Data.Foldable (class Foldable)
-import Data.Traversable (class Traversable)
 import Data.Newtype (class Newtype)
 import Data.Ord (class Ord1)
+import Data.Traversable (class Traversable)
 import Effect.Class (class MonadEffect)
 
 -- | The `IdentityT` monad transformer.
@@ -67,3 +68,9 @@ derive newtype instance monadTellIdentityT :: MonadTell w m => MonadTell w (Iden
 derive newtype instance monadWriterIdentityT :: MonadWriter w m => MonadWriter w (IdentityT m)
 derive newtype instance foldableIdentityT :: Foldable m => Foldable (IdentityT m)
 derive newtype instance traversableIdentityT :: Traversable m => Traversable (IdentityT m)
+
+instance extendIdentityI :: Extend w => Extend (IdentityT w) where
+  extend f (IdentityT m) = IdentityT (extend (f <<< IdentityT) m)
+
+instance comonadIdentityT :: Comonad w => Comonad (IdentityT w) where
+  extract = extract <<< runIdentityT