Data commit

Task/Ternary-logic/Haskell/ternary-logic.hs

@@ -0,0 +1,37 @@
+import Prelude hiding (Bool(..), not, (&&), (||), (==))
+
+main = mapM_ (putStrLn . unlines . map unwords)
+    [ table "not"     $ unary not
+    , table "and"     $ binary (&&)
+    , table "or"      $ binary (||)
+    , table "implies" $ binary (=->)
+    , table "equals"  $ binary (==)
+    ]
+
+data Trit = False | Maybe | True deriving (Show)
+
+False `nand` _     = True
+_     `nand` False = True
+True  `nand` True  = False
+_     `nand` _     = Maybe
+
+not a = nand a a
+
+a && b = not $ a `nand` b
+
+a || b = not a `nand` not b
+
+a =-> b = a `nand` not b
+
+a == b = (a && b) || (not a && not b)
+
+inputs1 = [True, Maybe, False]
+inputs2 = [(a,b) | a <- inputs1, b <- inputs1]
+
+unary f = map (\a -> [a, f a]) inputs1
+binary f = map (\(a,b) -> [a, b, f a b]) inputs2
+
+table name xs = map (map pad) . (header :) $ map (map show) xs
+    where header = map (:[]) (take ((length $ head xs) - 1) ['A'..]) ++ [name]
+
+pad s = s ++ replicate (5 - length s) ' '