FP Laboratory 6

Operators

• Define following functions that performs corresponding logic operations: not', and', or', nand', xor', impl', equ'
• Define the 'standard' priority for all these functions, if they are used as operators.
• Create a function that prints the truth table of a given logical expression for two variables.

table :: (Bool -> Bool -> Bool) -> IO ()

table (\a b -> (and' a (or' a b)))                                                                              
True True True
True False True
False True False
False False False

• Extend the previously defined function to accept any number of variables (the number of variables will be given as a first parameter).

tablen :: Int -> ([Bool] -> Bool) -> IO ()

 tablen 3 (\[a,b,c] -> a `and'` (b `or'` c) `equ'` a `and'` b `or'` a `and'` c)
True   True   True   => True
True   True   False  => True
True   False  True   => True
True   False  False  => False
False  True   True   => False
False  True   False  => False
False  False  True   => False
False  False  False  => False

Complex function - Huffman Codes

• Create a function that will compute Huffman codes for a given list of characters and their frequencies.

huffman :: [(Char, Int)] -> [(Char, String)]

*Main>  huffman [('a',45),('b',13),('c',12),('d',16),('e',9),('f',5)]
[('a',"0"),('b',"101"),('c',"100"),('d',"111"),('e',"1101"),('f',"1100")]