#7 Polish selector

lib/Selector.hs

@@ -1,5 +1,6 @@
 module Selector
 ( Selector (..)
+, Coordinate
 , Direction (..)
 
 , initSelector
@@ -8,6 +9,7 @@ module Selector
 , select
 , deselect
 , toggleSelection
+, getSelected
 
 , moveUp
 , moveDown
@@ -38,7 +40,7 @@ data Selector = Selector {
     position :: Coordinate,
     -- The card(s) that the selector currently holds.
     selected :: Maybe Coordinate
-} deriving (Show)
+} deriving (Show, Eq)
 
 ----------------------------------------------------------------------
 
@@ -64,16 +66,25 @@ move D = moveBy (diff !! 1)
 move L = moveBy (diff !! 2)
 move R = moveBy (diff !! 3)
 
+-- Select the current position.
 select :: Selector -> Selector
 select s@Selector{ position = pos } = s{ selected = Just pos }
 
+-- Deselect the current selection.
 deselect :: Selector -> Selector
 deselect s = s{ selected = Nothing }
 
+-- Toggle the selection of the selector. Deselect if any position is
+-- selected, otherwise select the current position.
 toggleSelection :: Selector -> Selector
 toggleSelection s@Selector{ selected = Nothing } = select s
 toggleSelection s                                = deselect s
 
+-- Get the selected coordinate, otherwise get (0,0) by default.
+getSelected :: Selector -> Coordinate
+getSelected s@Selector{ selected = Just c  } = c
+getSelected s@Selector{ selected = Nothing } = (0,0)
+
 ----------------------------------------------------------------------
 
 -- Move the selector up one position.