Truth Table Generator

ttable.hs

import Data.List (intercalate)
import Prelude hiding (or, and)

toBinArray :: Int -> [Bool]
toBinArray = reverse . helper
    where helper :: Int -> [Bool]
          helper 0 = [False]
          helper n 
            | n `div` 2 == 0 = [(n `mod` 2) /= 0]
            | otherwise = ((n `mod` 2) /= 0) : helper (n `div` 2)

boolTable :: Int -> [[Bool]]
boolTable n = map ((pad len) . toBinArray) [0..n - 1]
    where len = ceiling ((log $ fromIntegral n) / (log 2))

          pad :: Int -> [Bool] -> [Bool]
          pad len ls 
            | (length ls) < len = pad len (False : ls)
            | otherwise = ls

ttable :: ([Bool] -> Bool) -> Int -> [[Int]]
ttable f len = map (map fromEnum) boolTruthTable
    where table = boolTable len
          right_col = map f table

          boolTruthTable = map (\(row, result) -> row ++ [result]) (zip table right_col)

or ls = foldl (||) True ls
and ls = foldl (&&) True ls

implies [False, False] = True
implies [False, True]  = True
implies [True, False]  = False
implies [True, True]   = True

neg [p] = not p

printTable :: ([Bool] -> Bool) -> Int -> IO ()
printTable f len = putStrLn $ intercalate "\n" $ map show (ttable f len)