Control.Monad.Trans.Uplift

Documentation

uplift :: forall t f a. Uplift (IndexOf t f) f => Substack (IndexOf t f) f a -> f a

Uplift the substack starting with the given transformer into the full stack. This function is expected to be used with type applications when working with polymorphic code.

type family Substack n f where ...

A type family for computing the substack of a monad transformer stack, dropping the top n transformers.

Equations

Substack 'Z f = f

Substack ('S n) (t f) = Substack n f

class Uplift n f

A class for lifting arbitrary substacks of our transformer stack.

Minimal complete definition

liftSubstack

Instances

Uplift 'Z (f :: k -> Type)

Defined in Control.Monad.Trans.Uplift

Methods

liftSubstack :: forall (a :: k0). Substack 'Z f a -> f a

(Monad f, MonadTrans t, Uplift n f) => Uplift ('S n) (t f :: Type -> Type)

Defined in Control.Monad.Trans.Uplift

Methods

liftSubstack :: forall (a :: k). Substack ('S n) (t f) a -> t f a

type family IndexOf t f where ...

A type family for computing the index of a particular transformer in a stack.

Equations

IndexOf t (t f) = 'Z

IndexOf t (t' f) = 'S (IndexOf t f)

data N

Type level natural numbers

Constructors

S N

Z