-------------------------------------------------------------------------------
--  $Id: Col.hs#1 2009/10/01 10:31:09 REDMOND\\satnams $
-------------------------------------------------------------------------------

module Lava.Col
where
import Lava.Below

-------------------------------------------------------------------------------

col :: Monad m => Int ->                    -- number of elements in col
                  ((a, b) -> m (c, a)) ->   -- type of element circuit r
                  (a, [b]) ->               -- input to the col
                  m ([c], a)                -- output of the col
col n r (_, bus) | length bus /= n
  = error ("col shape error: col " ++ show n ++ " but input bus is size " ++
          show (length bus) ++ "\n")
col 1 r (a, [b])
  = do (c,d) <- r (a, b)
       return ([c],d)
col n r (a, b:bs)
  =  do ((c,cs), d) <- (r `below` (col (n-1) r)) (a, (b, bs))
        return (c:cs, d)

-------------------------------------------------------------------------------
-- 4-Sided Tile Combinators
-------------------------------------------------------------------------------
-- COL r
--            a
--            ^
--            |
--          -----
--         |     |
--     b ->|  r  |-> c
--         |     |
--          -----
--            ^
--            |
--            a
--            ^
--            |
--          -----
--         |     |
--     b ->|  r  |-> c
--         |     |
--          -----
--            ^ 
--            |
--            a
--            ^
--            |
--          -----
--         |     |
--     b ->|  r  |-> c
--         |     |
--          -----
--            ^ 
--            |
--            a
-------------------------------------------------------------------------------