Craft3e-0.1.1.0: Chapter15/Types.hs

-------------------------------------------------------------------------
--  
--         Types.hs                         
--  
--         The types used in the Huffman coding example.            
--                                  
--         (c) Addison-Wesley, 1996-2011.                   
--  
-------------------------------------------------------------------------

-- The interface to the module Types is written out     
-- explicitly here, after the module name.                      

module Types ( Tree(Leaf,Node), Bit(L,R),  
               HCode , Table  ) where

-- Trees to represent the relative frequencies of characters    
-- and therefore the Huffman codes.                     

data Tree = Leaf Char Int | Node Int Tree Tree

-- The types of bits, Huffman codes and tables of Huffman codes.    

data Bit = L | R deriving (Eq,Show)

type HCode = [Bit]

type Table = [ (Char,HCode) ]