Craft3e-0.1.0.2: 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) ]