Îõ³h& ý Ð8      !"#$%&'()*+,-./01234567 Trustworthy)*<ÂÙÚ º boringA helper class to implement of 8 derivation of . ôtype GAbsurd f = (Absurd (f ()), Functor f) gabsurd :: forall f x y. GAbsurd f => f x -> y gabsurd = absurd . void boringA helper class to implement 8 derivation of ."Technically we could do (avoiding QuantifiedConstraints): €type GBoring f = (Boring (f V.Void), Functor f) gboring :: forall f x. GBoring f => f x gboring = vacuous (boring :: f V.Void) but separate class is cleaner.+data B2 = B2 () () deriving (Show, Generic)instance Boring B2 boring :: B2B2 () ()boringThe « type is very exciting, because if somebody ever gives you a value belonging to it, you know that you are already dead and in Heaven and that anything you want is yours.Similarly as there are many  sums, there are many  products, so we don't have  instances for tuples.boring' types which contains one thing, also Ò. There is nothing interesting to be gained by comparing one element of the boring type with another, because there is nothing to learn about an element of the boring type by giving it any of your attention. Boring Law:  == x Note: This is different class from Default. Default gives you some value, Boring gives you an unique value.3Also note, that we cannot have instances for e.g. 9 , as both ( a,  b) => Either a b and ( a,  b) => Either a b would be valid instances.ÁAnother useful trick, is that you can rewrite computations with  results, for example foo :: Int -> (), if you are sure that foo is total. +{-# RULES "less expensive" foo = boring #-})That's particularly useful with equality :~: proofs.boringIf  is uninhabited then any :! that holds only values of type  is holding no values.boring'There is a field for every type in the  . Very zen.  ::  s => Over p f s s a b -type Over p f s t a b = p a (f b) -> s -> f tboringWe can always retrieve a  value from any type.  ::  a => Lens' s a boringHeterogeneous type equality is  too.boringHomogeneous type equality is  too.6boring; a = a + 1,  0 + 1 = 1.7boringÃRecall regular expressions, kleene star of empty regexp is epsilon!  <      !"#$%&'()*+,-./0123456789:;<:=>:?@:ABÃ#boring-0.2.1-IaXkgEDxwCMIujJXvLiLSM Data.BoringGAbsurdGBoringAbsurdabsurdBoringboringvacuousdevoidunited $fGBoring:*: $fGBoringM1 $fGBoringU1 $fGBoringK1 $fBoring:.: $fBoringRec1 $fBoringPar1 $fBoring:*: $fBoringM1 $fBoringK1 $fBoringU1$fBoringTypeRep $fBoring:~~: $fBoring:~:$fBoring(,,,,) $fBoring(,,,) $fBoring(,,) $fBoring(,)$fBoringProduct$fBoringCompose$fBoringIdentity$fBoringTagged $fBoringConst $fBoringProxy $fBoringFUN $fBoring() $fGAbsurd:+: $fGAbsurdM1 $fGAbsurdV1 $fGAbsurdK1 $fAbsurd:.: $fAbsurdRec1 $fAbsurdPar1 $fAbsurd:+: $fAbsurdM1 $fAbsurdK1 $fAbsurdV1$fAbsurdTagged $fAbsurdConst $fAbsurdSum$fAbsurdCompose$fAbsurdIdentity$fAbsurdNonEmpty$fAbsurdEither $fAbsurdVoid $fBoringMaybe $fBoring[]base GHC.GenericsGeneric Data.EitherEitherGHC.BaseFunctor GHC.MaybeMaybe