probando :: ST s ( STArray s (Int,Int) Char) -> (Int, Int) ->  [[Char]]
probando tab pos = do 
  let w = runSTArray tab
  if noValidM w pos 
     then return []
     else do  
       dir <- "ldru" 
       guard ( isValidM  pos w dir )        
       let (pos',tab') = (mov dir pos w, act tab pos pos') 
       y <- ( probando tab' pos')
       return (dir : y)

noValidM :: Array (Int, Int) Char -> (Int, Int) -> Bool
isValidP :: (Int,Int) -> Array (Int,Int) Char -> Bool
mov :: Char -> (Int, Int) -> Array (Int, Int) Char -> (Int, Int)
{-
STArray.hs:110:22:
    Couldn't match type `s' with `s1'
      `s' is a rigid type variable bound by
          the type signature for
            probando :: ST s (STArray s (Int, Int) Char)
                        -> (Int, Int) -> [[Char]]
          at STArray.hs:109:1
      `s1' is a rigid type variable bound by
           a type expected by the context: ST s1 (STArray s1 (Int, Int) Char)
           at STArray.hs:110:11
    Expected type: ST s1 (STArray s1 (Int, Int) Char)
      Actual type: ST s (STArray s (Int, Int) Char)
    In the first argument of `runSTArray', namely `tab'
    In the expression: runSTArray tab
-}