Types.lhs							
 
        The types used in the Huffman coding example.			
									
        (c) Simon Thompson, 1995, 1998					


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) ]