-- | Return the co-ordinates of all points in the chain of which the
-- supplied point is a member.  A point is a member of a chain if there
-- is a direct line, horizontally or vertically, leading to another point
-- of the same colour.
-- Requesting the chain for an Empty point returns the contiguous range
-- of empty points.
chain :: Player p => Board p -> (Int, Int) -> [(Int, Int)]
chain b = map repaCoordsToTuple . B.chain b . tupleToRepaCoords
chain :: Player p => Board p -> (Int, Int) -> [(Int, Int)]
chain b = map repaCoordsToTuple . B.chain b . tupleToRepaCoords
chain b = map repaCoordsToTuple . B.chain b . tupleToRepaCoords