Data.StableTree.Persist

Logic for dealing with the actual persistence of Stable Trees. The key exports here are Error, Store, load, and store. A user needs to implement the loadTree, loadValue, storeTree and storeValue parts of Store, and make an appropriate Error type to report storage errors, and then the load and store functions can just do their thing. If necessary, a user can also implement Build for custom data types.

Documentation

data Store m e k v

Write appropriate functions here to load and store primitive parts of trees.

Constructors

Store

Fields

loadTree :: Id -> m (Either e (Depth, Map k (ValueCount, Id)))

loadValue :: Id -> m (Either e v)

storeTree :: Id -> Depth -> Map k (ValueCount, Id) -> m (Maybe e)

storeValue :: Id -> v -> m (Maybe e)

class Build t where

Typeclass to generate unique ByteStrings for StableTree keys and values. Used to generate the unique identities for values and branches.

Methods

build :: t -> Builder

Instances

Build Char

Build Double

Build Float

Build Int

Build Int8

Build Int16

Build Int32

Build Int64

Build Integer

Build Word

Build Word8

Build Word16

Build Word32

Build Word64

Build ByteString

Build ByteString

Build Id

class Error e where

Things go wrong with end-user storage, but things can also go wrong with reconstructing tree values. Implement stableTreeError to allow load and store to report their own errors.

Methods

stableTreeError :: Text -> e

Instances

Error RamError

data Id

The opaque type to identify values and branches of trees.

Instances

Eq Id

Ord Id

Show Id

Build Id

encodeId :: Id -> ByteString

Convert an Id into a 32-byte ByteString. Useful for actual storage of Ids

decodeId :: ByteString -> Either String Id

Convert a stored ByteString back into an Id. Gives a Left err if the given ByteString isn't 32 bytes long

load :: (Monad m, IsKey k, Ord k, Error e) => Store m e k v -> Id -> m (Either e (StableTree k v))

Retrieve a tree given its id.

store :: (Monad m, Build k, Ord k, Build v) => Store m e k v -> StableTree k v -> m (Either e Id)

Store a tree using a Store and return its calculated Id

buildBinary :: Binary t => t -> Builder

Generate a builder for something that is already a Binary

buildSerialize :: Serialize t => t -> Builder

Generate a builder for something that is already a Serialize