A typed, persistent store for values of arbitrary types. This is a port of the haskell Vault library Heinrich Apfelmus.
Think of it as Map that can store for values of arbitrary types, but it's type-safe.
You can store of any types by creating Key a first, this key used to parameterized the
type you are going to store in vault.
In summary a vault API:
data Vault
data Key a
newKey :: forall e a. Eff (ref :: REF | e) (Key a)
empty :: Vault
lookup :: forall a. Key a -> Vault -> Maybe a
insert :: forall a. Key a -> a -> Vault -> Vault
delete :: forall a. Key a -> Vault -> Vault