Work on a selection list datatype

src/Dodge/Render/List.hs

@@ -1,5 +1,6 @@
 module Dodge.Render.List where
 
+import ListHelp
 import Dodge.Data.SelectionList
 import Data.Foldable
 import Data.Maybe
@@ -18,6 +19,25 @@ drawSelectionList cfig sl = listPicturesAtScaleOff
     cfig
     (_slOffset sl)
     (concatMap _siPictures (_slItems sl))
+    <> drawSelectionCursor cfig sl
+
+drawSelectionCursor :: Configuration -> SelectionList -> Picture
+drawSelectionCursor cfig sl = fromMaybe mempty $ do
+    i <- _slSelPos sl
+    selit <- (filter _siIsSelectable lis) !? i
+    f <- case _slCursorType sl of
+        NSEWCursor -> Just listCursorNESW
+        NSWCursor -> Just listCursorNSW
+        NSCursor -> Just listCursorNS
+        NoCursor -> Nothing
+    let j = sum . map _siHeight $ takeWhileArb (<= i) (\x itsel -> x + if _siIsSelectable itsel then 1 else 0) 0 lis
+        col = _siColor selit
+    return $ f (_slPosX sl + (9 * fromIntegral (_siOffX selit))) (_slPosY sl) cfig j col wdth (_siHeight selit)
+  where
+    lis = _slItems sl
+    wdth = case _slWidth sl of
+        FixedSelectionWidth x -> x
+        _ -> 1
 
 -- given a list of pictures that are each the size of a "text" call, displays them as
 -- a list on the screen