ToySolver.Data.LBool

Lifted boolean type.

Documentation

data LBool

Lifted Bool type. It has three values lTrue, lFalse, lUndef.

Instances

Eq LBool

Show LBool

lTrue :: LBool

lifted true value

lFalse :: LBool

lifted false value

lUndef :: LBool

undefined truth value

lnot :: LBool -> LBool

  lnot lTrue == lFalse
  lnot lFalse == lTrue
  lnot lUndef == lUndef

liftBool :: Bool -> LBool

  liftBool True == lTrue
  liftBool False == lFalse

unliftBool :: LBool -> Maybe Bool

  unliftBool lTrue == Just True
  unliftBool lFalse == Just False
  unliftBool lUndef == Nothing