src/Control/Monad/Logic/Class.purs

@@ -3,8 +3,8 @@ module Control.Monad.Logic.Class (class MonadLogic, msplit, interleave, fbind, r
 import Prelude
 
 import Control.MonadPlus (class MonadPlus, (<|>), empty)
-import Control.Monad.State.Trans (StateT(..), runStateT)
-import Control.Monad.Reader.Trans (ReaderT(..), runReaderT)
+import Control.Monad.State (runStateT)
+import Control.Monad.State.Trans (StateT(..))
 import Data.Tuple.Nested (type (/\), (/\))
 import Data.Maybe (Maybe(..))
 
@@ -32,10 +32,3 @@ instance MonadLogic m => MonadLogic (StateT s m) where
             Nothing -> pure (Nothing /\ s)
             Just ((a /\ s') /\ m) -> pure (Just (a /\ (StateT $ const m)) /\ s')
     interleave m1 m2 = StateT $ \s -> runStateT m1 s <|> runStateT m2 s
-
-instance MonadLogic m => MonadLogic (ReaderT r m) where
-    msplit sm = ReaderT $ \r -> do
-        msplit (runReaderT sm r) >>= case _ of
-            Nothing -> pure Nothing
-            Just (a /\ m) -> pure $ Just $ a /\ (ReaderT $ const m)
-    interleave m1 m2 = ReaderT $ \r -> runReaderT m1 r <|> runReaderT m2 r

test/Main.purs

@@ -4,11 +4,12 @@ import Prelude
 
 import Control.Alternative (guard, (<|>))
 import Control.Monad.Logic.Class (class MonadLogic, interleave)
-import Control.Monad.Logic.Trans (runSFKT)
+import Control.Monad.Logic.Trans (SFKT, runSFKT)
 import Control.Monad.Reader.Class (class MonadReader)
 import Control.Monad.Reader.Trans (runReaderT, ask)
 import Control.Monad.State.Class (class MonadState)
 import Control.Monad.State.Trans (runStateT, put, get)
+import Data.List (List(..), (:))
 import Data.Maybe (Maybe)
 import Data.Tuple (fst)
 import Data.Tuple.Nested(type (/\), (/\))
@@ -25,14 +26,17 @@ test =
             newState <- get
             pure ((offset+n) /\ (oldState <> " became " <> newState))
 
+solutions :: forall a m. Monad m => SFKT m a -> m (List a)
+solutions m = runSFKT m ((<$>) <<< (:)) (pure Nil)
+
 order1 :: Maybe String
-order1 = show <$> (runReaderT (runSFKT (fst <$> runStateT (test >>= \(x /\ s) -> guard (x `mod` 2 == 1) >>= \_ -> pure (x /\ s)) "initial")) 11)
+order1 = show <$> (runReaderT (solutions (fst <$> runStateT (test >>= \(x /\ s) -> guard (x `mod` 2 == 1) >>= \_ -> pure (x /\ s)) "initial")) 11)
 
 order2 :: Maybe String
-order2 = show <$> fst <$> (runStateT (runReaderT (runSFKT (test >>= \(x /\ s) -> guard (x `mod` 2 == 1) >>= \_ -> pure (x /\ s))) 11) "initial")
+order2 = show <$> fst <$> (runStateT (runReaderT (solutions (test >>= \(x /\ s) -> guard (x `mod` 2 == 1) >>= \_ -> pure (x /\ s))) 11) "initial")
 
 order3 :: Maybe String
-order3 = show <$> fst <$> (runStateT (runReaderT (runSFKT test) 0) "initial")
+order3 = show <$> fst <$> (runStateT (runReaderT (solutions test) 0) "initial")
 
 main :: Maybe String
 main = order1