Data.Vault.ST

Synopsis

A persistent store for values of arbitrary types. Variant for the ST monad.

Vault

type Vault = Vault

A persistent store for values of arbitrary types.

This variant is the simplest and creates keys in the IO monad. See the module Data.Vault.ST if you want to use it with the ST monad instead.

 type Vault :: * -> *
 instance Monoid Vault

type Key = Key

Keys for the vault.

 type Key :: * -> * -> *

empty :: Vault s

The empty vault.

newKey :: ST s (Key s a)

Create a new key for use with a vault.

lookup :: Key s a -> Vault s -> Maybe a

Lookup the value of a key in the vault.

insert :: Key s a -> a -> Vault s -> Vault s

Insert a value for a given key. Overwrites any previous value.

adjust :: (a -> a) -> Key s a -> Vault s -> Vault s

Adjust the value for a given key if it's present in the vault.

delete :: Key s a -> Vault s -> Vault s

Delete a key from the vault.

union :: Vault s -> Vault s -> Vault s

Merge two vaults (left-biased).

Locker

type Locker = Locker

A persistent store for a single value.

 type Locker :: * -> *

lock :: Key s a -> a -> Locker s

Put a single value into a Locker.

unlock :: Key s a -> Locker s -> Maybe a

Retrieve the value from the Locker.