Huffman algorithm

[matush23@netscape.net]

Hi, I have problems with assignation of types, I did this ...

***** End: -- Codigo de Huffman
The rest of the message is ignored:
> --
> -- 
> -- Un arbol binario comun
> --
> data BinTree a = Hoja a
>            | Nodo (BinTree a) (BinTree a)
> 
> type Huff = BinTree Char
> 
> -- Arbol especifico para la funcion `combinar'
> --
> data Tree = Leaf Int Char
>       | Node Int Tree Tree
> 
> -- Binary search tree para la funcion `freqs'
> --
> data BSTree a = Nil | BSNode a (BSTree a) (BSTree a)
> 
> 
> 
> -- Calculo de las frequencias de cada letra
> --
> freq          :: BSTree (Char,Int) -> String -> BSTree (Char,Int)
> freq t []     = t
> freq t (x:xs) = insertTree x (freq t xs)
> 
> insertTree                               :: Char -> BSTree (Char,Int) -> BSTree (Char,Int)
> insertTree x Nil                         = BSNode (x,1) Nil Nil
> insertTree x (BSNode (c,n) t1 t2) | x==c = BSNode (c,n+1) t1 t2
>                                   | x<c  = BSNode (c,n) (insertTree x t1) t2
>                                   | x>c  = BSNode (c,n) t1 (insertTree x t2)
> 
> flatten                  :: BSTree a -> [a]
> flatten Nil              = []
> flatten (BSNode x t1 t2) = [x] ++ (flatten t1) ++ (flatten t2)
> 
> iSort        :: [(Char,Int)] -> [(Char,Int)]
> iSort []     = []
> iSort (x:xs) = ins x (iSort xs)
> 
> ins                                  :: (Char,Int) -> [(Char,Int)] -> [(Char,Int)]
> ins a []                             = [a]
> ins a@(c,n) l@((d,m):xs) | n<=m      = a:l
>              | otherwise = (d,m):ins a xs
> 
> freqs :: String -> [(Char,Int)]
> freqs xs = (iSort . flatten) (freq Nil xs)
> 
> 
> 
> -- Decodificacion
> --
> decodificar :: [Int] -> Huff -> String
> decodificar xs t = aux xs t t
>     where aux [] (Hoja c) t         = [c]
>       aux (x:xs) (Hoja c) t     = [c] ++ aux (x:xs) t t
>       aux (0:xs) (Nodo t1 t2) t = aux xs t1 t
>       aux (1:xs) (Nodo t1 t2) t = aux xs t2 t
> 
> 
> 
> -- Codificacion respecto a un arbol dado
> --
> cod :: Char -> Huff -> [Int]
> cod c t = head (aux c t)
>     where aux c (Hoja d) | c==d      = [[]]
>              | otherwise = []
>       aux c (Nodo t1 t2)         = [ (0:xs) | xs <- aux c t1 ] ++
>                        [ (1:xs) | xs <- aux c t2 ]
> 
> codificar :: String -> Huff -> [Int]
> codificar xs t = concat (map (\c->cod c t) xs)
> 
> 
> 
> 
> --Construccion del arbol de Huffman
> --
> combinar            :: [Tree] -> [Tree]
> combinar [t]        = [t]
> combinar (t1:t2:ts) = insert (Node (w1+w2) t1 t2) ts
>     where weight (Leaf n x)                     = n
>       weight (Node n _ _)                   = n
>       insert t []                           = [t]
>       insert t (u:us) | weight t < weight u = t:u:us
>               | otherwise           = u:(insert t us)
>       w1                                    = weight t1
>       w2                                    = weight t2
> 
> combinarTodos     :: [Tree] -> Tree
> combinarTodos [t] = t
> combinarTodos ts  = combinarTodos (combinar ts)
> 
> 
> 
> -- Pegamos la construccion del arbol y la codificacion del texto
> --
> codificarTexto    :: String -> ([Int], Huff)
> codificarTexto xs = (ys, t)
>     where ls                       = freqs xs
>       desmarcar (Leaf n x)     = Hoja x
>       desmarcar (Node n t1 t2) = Nodo (desmarcar t1) (desmarcar t2)
>       t                        = (desmarcar . combinarTodos) (map (\(c,n)->Leaf n c) ls)
>       ys = codificar xs t
> 
> 
> 
> 
> -- Example
> --
> prueba1 = let (s, t) = codificarTexto "Salvete, omnes"
>       in decodificar s t
> 
> 
> 
> "Please, I need help.



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