| Portability | portable |
|---|---|
| Stability | provisional |
| Maintainer | Edward Kmett <ekmett@gmail.com> |
| Safe Haskell | Safe-Infered |
Control.Comonad.Trans.Store.Memo
Description
The memoizing store (state-in-context/costate) comonad transformer is subject to the laws:
x = seek (pos x) x y = pos (seek y x) seek y x = seek y (seek z x)
This version of the transformer lazily memoizes the result of applying the comonad to the current state. This can be useful for avoiding redundant computation if you reuse the same StoreT object multiple times.
- type Store s = StoreT s Identity
- store :: (s -> a) -> s -> Store s a
- runStore :: Store s a -> (s -> a, s)
- data StoreT s w a
- storeT :: Functor w => w (s -> a) -> s -> StoreT s w a
- runStoreT :: StoreT s w a -> (w (s -> a), s)
- lowerStoreT :: StoreT s w a -> w a
- pos :: StoreT s w a -> s
- seek :: Comonad w => s -> StoreT s w a -> StoreT s w a
- seeks :: Comonad w => (s -> s) -> StoreT s w a -> StoreT s w a
- peek :: Comonad w => s -> StoreT s w a -> a
- peeks :: Comonad w => (s -> s) -> StoreT s w a -> a
The Store comonad
The Store comonad transformer
Instances
| ComonadTrans (StoreT s) | |
| ComonadHoist (StoreT s) | |
| Functor w => Functor (StoreT s w) | |
| (Typeable s, Typeable1 w) => Typeable1 (StoreT s w) | |
| (Applicative w, Semigroup s, Monoid s) => Applicative (StoreT s w) | |
| Comonad w => Comonad (StoreT s w) | |
| Extend w => Extend (StoreT s w) | |
| (Apply w, Semigroup s) => Apply (StoreT s w) | |
| (Typeable s, Typeable1 w, Typeable a) => Typeable (StoreT s w a) |
lowerStoreT :: StoreT s w a -> w aSource
Operations
seek :: Comonad w => s -> StoreT s w a -> StoreT s w aSource
Seek to an absolute location
seek s = peek s . duplicate
seeks :: Comonad w => (s -> s) -> StoreT s w a -> StoreT s w aSource
Seek to a relative location
seeks f = peeks f . duplicate