Control.Invertible.BiArrow

Bidirectional arrows. Taken directly from

• Artem Alimarine, et al. There and Back Again: Arrows for Invertible Programming. Haskell '05. http://citeseer.ist.psu.edu/alimarine05there.html

Documentation

class (Groupoid a, Category a) => BiArrow a where

The bidirectional arrow class.

Instances should satisfy the following laws:

• f1 <-> g2 >>> g1 <-> f2 = (f1 >>> g1) <-> (f2 >>> g2)

• invert (invert f) = f

• invert (f <-> g) = g <-> f

• first (f <-> g) = f *** id <-> g *** id

• first h >>> id *** f <-> id *** g = id *** f <-> id *** g >>> first h

• first (first f) >>> assoc = assoc >>> first f

where assoc = [biCase|((x,y),z) <-> (x,(y,z))|]

Minimal complete definition

(<->)

Methods

(<->) :: (b -> c) -> (c -> b) -> a b c infix 2

Take two functions and lift them into a bidirectional arrow. The intention is that these functions are each other's inverse.

invert :: a b c -> a c b

Inverse: reverse the direction of a bidirectional arrow.

Instances

BiArrow Iso

Defined in Control.Invertible.BiArrow

Methods

(<->) :: (b -> c) -> (c -> b) -> Iso b c

invert :: Iso b c -> Iso c b

(Semigroupoid a, Arrow a) => BiArrow (Bijection a)

Defined in Control.Invertible.BiArrow

Methods

(<->) :: (b -> c) -> (c -> b) -> Bijection a b c

invert :: Bijection a b c -> Bijection a c b

(BiArrow a, Monad m) => BiArrow (MonadArrow a m)

Defined in Control.Invertible.MonadArrow

Methods

(<->) :: (b -> c) -> (c -> b) -> MonadArrow a m b c

invert :: MonadArrow a m b c -> MonadArrow a m c b

(Semigroupoid a, Arrow a) => BiArrow (Iso a)

Defined in Control.Invertible.BiArrow

Methods

(<->) :: (b -> c) -> (c -> b) -> Iso a b c

invert :: Iso a b c -> Iso a c b

class (BiArrow a, Arrow a) => BiArrow' a

Bidirectional arrows under Arrow.

Although BiArrow should not, strictly speaking, be a subclass of Arrow (as it is often impossible to define arr), this is done because (as the paper says) "conceptually bi-arrows form an extension of the arrow class. Moreover, it allows us to use bi-arrows as normal arrows." This class exists to register this confound.

Instances

(Semigroupoid a, Arrow a) => BiArrow' (Bijection a)

Defined in Control.Invertible.BiArrow

Monad m => BiArrow' (MonadArrow (<->) m)

Defined in Control.Invertible.MonadArrow

biarr :: BiArrow a => (b <-> c) -> a b c

Lift a bidirectional function to an arbitrary arrow using BiArrow.

involve :: BiArrow a => (b -> b) -> a b b

Construct an involution (a biarrow where the function and inverse are the same).

(^^>>) :: BiArrow a => (b <-> c) -> a c d -> a b d infixr 1

Precomposition with a pure bijection.

(>>^^) :: BiArrow a => a b c -> (c <-> d) -> a b d infixr 1

Postcomposition with a pure bijection.

(<<^^) :: BiArrow a => a c d -> (b <-> c) -> a b d infixr 1

Precomposition with a pure bijection (right-to-left variant).

(^^<<) :: BiArrow a => (c <-> d) -> a b c -> a b d infixr 1

Postcomposition with a pure bijection (right-to-left variant).

type BiKleisli m = Bijection (Kleisli m)

Bidirectional Kleisli monad arrow transformer.

Orphan instances

Groupoid Iso

Poor orphans. Please will someone adopt us?

Methods

inv :: forall (a :: k) (b :: k). Iso a b -> Iso b a

Semigroupoid Iso

Poor orphans. Please will someone adopt us?

Methods

o :: forall (j :: k) (k1 :: k) (i :: k). Iso j k1 -> Iso i j -> Iso i k1