Data.Functor.Free

A free functor is left adjoint to a forgetful functor. In this package the forgetful functor forgets class constraints.

Documentation

newtype Free c a

The free functor for constraint c.

Constructors

Free

Fields

runFree :: forall b. c b => (a -> b) -> b

Instances

~ (* -> Constraint) c (Class f) => Algebra f (Free c a)

ForallF c (Free c) => Monad (Free c)

Functor (Free c)

Applicative (Free c)

ForallT c (LiftAFree c) => Foldable (Free c)

ForallT c (LiftAFree c) => Traversable (Free c)

(ForallF c Identity, ForallF c (Free c), ForallF c (Compose (Free c) (Free c))) => Comonad (Free c)

unit :: a -> Free c a

rightAdjunct :: c b => (a -> b) -> Free c a -> b

rightAdjunctF :: ForallF c f => (a -> f b) -> Free c a -> f b

rightAdjunctT :: ForallT c t => (a -> t f b) -> Free c a -> t f b

counit :: c a => Free c a -> a

counit = rightAdjunct id

leftAdjunct :: (Free c a -> b) -> a -> b

leftAdjunct f = f . unit

newtype LiftAFree c f a

Constructors

LiftAFree

Fields

getLiftAFree :: f (Free c a)

Instances

(Applicative f, ~ (* -> Constraint) c (Class s)) => Algebra s (LiftAFree c f a)

convert :: (c (f a), Applicative f) => Free c a -> f a

convertClosed :: c r => Free c Void -> r

type InitialObject c = Free c Void

initial :: c r => InitialObject c -> r

type Coproduct c m n = Free c (Either m n)

coproduct :: c r => (m -> r) -> (n -> r) -> Coproduct c m n -> r

inL :: c m => m -> Coproduct c m n

inR :: c n => n -> Coproduct c m n

product :: (r -> m) -> (r -> n) -> r -> Free c (m, n)

fstP :: c m => Free c (m, n) -> m

sndP :: c n => Free c (m, n) -> n