3 files changed, 22 insertions, 20 deletions
diff --git a/src/TextViewport/Viewport/Instance.hs b/src/TextViewport/Viewport/Instance.hs
index 1bafcbd..c3ce338 100644
--- a/src/TextViewport/Viewport/Instance.hs
+++ b/src/TextViewport/Viewport/Instance.hs
@@ -1,5 +1,7 @@
 module TextViewport.Viewport.Instance where
 
+import Data.Hashable (Hashable)
+import Data.Sequences (Index, Textual)
 import TextViewport.Buffer.Item
 import TextViewport.Buffer.Buffer (Buffer)
 import TextViewport.Buffer.Buffer qualified as Buffer
@@ -12,64 +14,64 @@ import TextViewport.Viewport.Viewport (Viewport, clampViewport, mkViewport)
 import TextViewport.Viewport.Viewport qualified as Viewport
 
 
-data Instance = Instance
-  { viRender :: RenderState
+data Instance a = Instance
+  { viRender :: RenderState a
   , viView   :: Viewport
   } deriving (Show)
 
-mkInstance :: Int -> Int -> Buffer -> Instance
+mkInstance :: (Hashable a, Textual a, Index a ~ Int) => Int -> Int -> Buffer a -> Instance a
 mkInstance width height buf =
   let rs = mkRenderState width buf
       vp = mkViewport width height rs
   in Instance rs vp
 
-visibleLines :: Instance -> [RenderedLine]
+visibleLines :: Instance a -> [RenderedLine a]
 visibleLines (Instance rs vp) =
   take (Viewport.vpHeight vp) . drop (Viewport.vpOffset vp) . RenderedBuffer.flatten $ RenderState.rsRendered rs
 
-applyToInstance :: (Viewport -> Viewport) -> Instance -> Instance
+applyToInstance :: (Viewport -> Viewport) -> Instance a -> Instance a
 applyToInstance f (Instance rs vp) =
   let vp' = f vp
   in Instance rs (clampViewport rs vp')
 
-applyToInstanceRS :: (RenderState -> Viewport -> Viewport) -> Instance -> Instance
+applyToInstanceRS :: (RenderState a -> Viewport -> Viewport) -> Instance a -> Instance a
 applyToInstanceRS f (Instance rs vp) =
   let vp' = f rs vp
   in Instance rs (clampViewport rs vp')
 
-scrollByI :: Int -> Instance -> Instance
+scrollByI :: Int -> Instance a -> Instance a
 scrollByI delta = applyToInstance (Viewport.scrollBy delta)
 
-scrollUpI :: Int -> Instance -> Instance
+scrollUpI :: Int -> Instance a -> Instance a
 scrollUpI delta = applyToInstance (Viewport.scrollUp delta)
 
-scrollDownI :: Int -> Instance -> Instance
+scrollDownI :: Int -> Instance a -> Instance a
 scrollDownI delta = applyToInstance (Viewport.scrollDown delta)
 
-pageUpI :: Instance -> Instance
+pageUpI :: Instance a -> Instance a
 pageUpI = applyToInstance Viewport.pageUp
 
-pageDownI :: Instance -> Instance
+pageDownI :: Instance a -> Instance a
 pageDownI = applyToInstance Viewport.pageDown
 
-alignTopI :: Instance -> Instance
+alignTopI :: Instance a -> Instance a
 alignTopI = applyToInstance Viewport.alignTop
 
-alignBottomI :: Instance -> Instance
+alignBottomI :: Instance a -> Instance a
 alignBottomI = applyToInstanceRS Viewport.alignBottom
 
-modifyItemI :: Int -> (Item -> Item) -> Instance -> Instance
+modifyItemI :: (Hashable a, Textual a, Index a ~ Int) => Int -> (Item a -> Item a) -> Instance a -> Instance a
 modifyItemI ix f (Instance rs vp) =
   let buf' = Buffer.modifyItem ix f (RenderState.rsBuffer rs)
       rs'  = mkRenderState (RenderState.rsWidth rs) buf'
       vp'  = clampViewport rs' vp
   in Instance rs' vp'
 
-lookupPositionI :: Int -> Int -> Instance -> Maybe (Int, Int)
+lookupPositionI :: Int -> Int -> Instance a -> Maybe (Int, Int)
 lookupPositionI x y (Instance rs vp) =
     lookupPosition x y vp (RenderState.rsRendered rs)
 
---debugVI :: Instance -> IO ()
+--debugVI :: Instance a -> IO ()
 --debugVI (Instance rs vp) = do
 --  putStrLn ("offset = " ++ show (Viewport.vpOffset vp))
 --  putStrLn ("height = " ++ show (Viewport.vpHeight vp))
diff --git a/src/TextViewport/Viewport/Position.hs b/src/TextViewport/Viewport/Position.hs
index 149fc9e..593bd67 100644
--- a/src/TextViewport/Viewport/Position.hs
+++ b/src/TextViewport/Viewport/Position.hs
@@ -10,7 +10,7 @@ lookupPosition
   :: Int
   -> Int
   -> Viewport
-  -> RenderedBuffer
+  -> RenderedBuffer a
   -> Maybe (Int, Int)
 lookupPosition x y vp rb =
   let allLines = RenderedBuffer.flatten rb
diff --git a/src/TextViewport/Viewport/Viewport.hs b/src/TextViewport/Viewport/Viewport.hs
index e6fdaab..65f48e4 100644
--- a/src/TextViewport/Viewport/Viewport.hs
+++ b/src/TextViewport/Viewport/Viewport.hs
@@ -10,7 +10,7 @@ data Viewport = Viewport
   , vpOffset :: !Int
   } deriving (Show)
 
-mkViewport :: Int -> Int -> RenderState -> Viewport
+mkViewport :: Int -> Int -> RenderState a -> Viewport
 mkViewport width height rs =
     alignBottom rs Viewport
       { vpWidth  = width
@@ -19,7 +19,7 @@ mkViewport width height rs =
       }
 
 -- any function that sets vpOffset and can overshoot should use clampViewport
-clampViewport :: RenderState -> Viewport -> Viewport
+clampViewport :: RenderState a -> Viewport -> Viewport
 clampViewport rs vp =
   let total  = RenderState.rsLineCount rs
       maxOff = max 0 (total - vpHeight vp)
@@ -48,7 +48,7 @@ alignTop :: Viewport -> Viewport
 alignTop vp =
   vp { vpOffset = 0 }
 
-alignBottom :: RenderState -> Viewport -> Viewport
+alignBottom :: RenderState a -> Viewport -> Viewport
 alignBottom rs vp =
   let total = RenderState.rsLineCount rs
       off   = max 0 (total - vpHeight vp)