command interpretation

1 files changed, 16 insertions, 7 deletions

diff --git a/src/Utils.hs b/src/Utils.hs
index 6c8f0c1..cac88ac 100644
--- a/src/Utils.hs
+++ b/src/Utils.hs
@@ -4,6 +4,7 @@ module Utils
        ( showEntity
        , apply, apply'
        , entities
+       , takeR
        ) where
 
 import Data.Text (Text)
@@ -20,6 +21,9 @@ import Control.Monad.Writer.Class
 import Data.Set (Set)
 import qualified Data.Set as Set
 
+import Data.Sequence (Seq, ViewR(..), (|>))
+import qualified Data.Sequence as Seq
+
 import Types
 
 showEntity :: Entity -> Text
@@ -27,14 +31,19 @@ showEntity (Entity name number)
   | (Just (show -> n)) <- number = name <> " № " <> Text.pack n
   | otherwise = name
 
-apply' :: (MonadState Sequence m, MonadWriter History m) => Alteration -> m ()
-apply' alteration = do
-  (newSt, hist) <- apply alteration <$> get
-  tell hist
-  put newSt
+apply' :: MonadState Context m => Alteration -> Comment -> m ()
+apply' alteration comment = modify $ onCtx (apply alteration comment)
+  where
+    onCtx f ctx = let (sequence', history') = f $ ctxSequence ctx in ctx { ctxSequence = sequence', ctxHistory = ctxHistory ctx <> history' }
 
-apply :: Alteration -> Sequence -> (Sequence, History)
-apply alteration seq = undefined
+apply :: Alteration -> Comment -> Sequence -> (Sequence, History)
+apply alteration comment seq = undefined
 
 entities :: MonadState Sequence m => m (Set Entity)
 entities = Set.fromList . MaxPQueue.elems <$> get
+
+takeR :: Integer -> Seq a -> Seq a
+takeR _ (Seq.viewr -> EmptyR) = Seq.empty
+takeR n (Seq.viewr -> (xs :> x))
+  | n <= 0 = Seq.empty
+  | otherwise = takeR (n - 1) xs |> x