liquidhaskell-0.9.0.2.1: tests/pos/CheckedNum.hs

module CheckedNum where

-- Hiding numeric operations, because they get by default translated to SMT equivalent
import Prelude hiding (Num(..))

import qualified Prelude as Prelude

class CheckedNum a where
  (+) :: a -> a -> a
  (-) :: a -> a -> a

{-@ predicate BoundInt X = 0 < X + 10000 && X < 10000 @-}

instance CheckedNum Int where
{-@ instance CheckedNum Int where
      - :: x:Int -> y:{v:Int | BoundInt (x - v)} -> {v: Int | v == x - y} ;
      + :: x:Int -> y:{v:Int | BoundInt (x + v)} -> {v: Int | v == x + y}
  @-}
    x - y = (Prelude.-) x y

    x + y = (Prelude.+) x y