diff options
| -rw-r--r-- | lec05/Calc.hs | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/lec05/Calc.hs b/lec05/Calc.hs index f97d784..7502b5f 100644 --- a/lec05/Calc.hs +++ b/lec05/Calc.hs @@ -31,3 +31,38 @@ instance Expr ExprT where reify :: ExprT -> ExprT reify = id + +-- Exercise 4 + +instance Expr Integer where + lit x = x + add l r = eval (Add (Lit l) (Lit r)) + mul l r = eval (Mul (Lit l) (Lit r)) + +instance Expr Bool where + lit x + | x <= 0 = False + | otherwise = True + add = (||) + mul = (&&) + +newtype MinMax = MinMax Integer deriving (Eq, Show) +newtype Mod7 = Mod7 Integer deriving (Eq, Show) + +instance Expr MinMax where + lit = MinMax + add (MinMax l) (MinMax r) = MinMax (max l r) + mul (MinMax l) (MinMax r) = MinMax (min l r) + +instance Expr Mod7 where + lit x = Mod7 (mod x 7) + add (Mod7 l) (Mod7 r) = Mod7 (mod (l + r) 7) + mul (Mod7 l) (Mod7 r) = Mod7 (mod (l * r) 7) + +testExp :: Expr a => Maybe a +testExp = parseExp lit add mul "(3 * -4) + 5" + +testInteger = testExp :: Maybe Integer +testBool = testExp :: Maybe Bool +testMM = testExp :: Maybe MinMax +testSat = testExp :: Maybe Mod7 |