```
data Exp = Number Int
| Add Exp Exp
| Subtract Exp Exp
| Multiply Exp Exp
| Divide Exp Exp
deriving (Show)
instance Num Exp where
x + y = Add x y
x - y = Subtract x y
x * y = Multiply x y
fromInteger x = Number . fromIntegral $ x
main = do
print (4 + 4 * 10 - 8 :: Exp)
```

# Small Arithmetic AST Example

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