Safe Haskell	None
Language	Haskell2010

Eventium.Store.Class

Contents

EventStore
Serialization
Utility types
Utility functions

Synopsis

newtype EventStoreReader key position (m :: Type -> Type) event = EventStoreReader {
- getEvents :: QueryRange key position -> m [event]
}
newtype EventStoreWriter key position (m :: Type -> Type) event = EventStoreWriter {
- storeEvents :: key -> ExpectedPosition position -> [event] -> m (Either (EventWriteError position) EventVersion)
}
type VersionedEventStoreReader (m :: Type -> Type) event = EventStoreReader UUID EventVersion m (VersionedStreamEvent event)
type GlobalEventStoreReader (m :: Type -> Type) event = EventStoreReader () SequenceNumber m (GlobalStreamEvent event)
type VersionedEventStoreWriter = EventStoreWriter UUID EventVersion
data StreamEvent key position event = StreamEvent {
- streamEventKey :: !key
- streamEventPosition :: !position
- streamEventEvent :: !event
}
type VersionedStreamEvent event = StreamEvent UUID EventVersion event
type GlobalStreamEvent event = StreamEvent () SequenceNumber (VersionedStreamEvent event)
data ExpectedPosition position
- = AnyPosition
- | NoStream
- | StreamExists
- | ExactPosition position
newtype EventWriteError position = EventStreamNotAtExpectedVersion position
runEventStoreReaderUsing :: (Monad m, Monad mstore) => (forall a. mstore a -> m a) -> EventStoreReader key position mstore event -> EventStoreReader key position m event
runEventStoreWriterUsing :: (Monad m, Monad mstore) => (forall a. mstore a -> m a) -> EventStoreWriter key posirion mstore event -> EventStoreWriter key posirion m event
module Eventium.Store.Queries
serializedEventStoreReader :: forall (m :: Type -> Type) event serialized key position. Monad m => Serializer event serialized -> EventStoreReader key position m serialized -> EventStoreReader key position m event
serializedVersionedEventStoreReader :: forall (m :: Type -> Type) event serialized. Monad m => Serializer event serialized -> VersionedEventStoreReader m serialized -> VersionedEventStoreReader m event
serializedGlobalEventStoreReader :: forall (m :: Type -> Type) event serialized. Monad m => Serializer event serialized -> GlobalEventStoreReader m serialized -> GlobalEventStoreReader m event
serializedEventStoreWriter :: forall (m :: Type -> Type) event serialized key position. Monad m => Serializer event serialized -> EventStoreWriter key position m serialized -> EventStoreWriter key position m event
newtype EventVersion = EventVersion {
- unEventVersion :: Int
}
newtype SequenceNumber = SequenceNumber {
- unSequenceNumber :: Int
}
transactionalExpectedWriteHelper :: (Monad m, Ord position, Num position) => (key -> m position) -> (key -> [event] -> m EventVersion) -> key -> ExpectedPosition position -> [event] -> m (Either (EventWriteError position) EventVersion)

EventStore

newtype EventStoreReader key position (m :: Type -> Type) event Source #

An EventStoreReader is a function to query a stream from an event store. It operates in some monad m and returns events of type event from a stream at key ordered by position.

Constructors

EventStoreReader
Fields getEvents :: QueryRange key position -> m [event]

Instances

Instances details

Functor m => Functor (EventStoreReader key position m) Source #
Instance details Defined in Eventium.Store.Class Methods fmap :: (a -> b) -> EventStoreReader key position m a -> EventStoreReader key position m b # (<$) :: a -> EventStoreReader key position m b -> EventStoreReader key position m a #

newtype EventStoreWriter key position (m :: Type -> Type) event Source #

An EventStoreWriter is a function to write some events of type event to an event store in some monad m.

Constructors

EventStoreWriter
Fields storeEvents :: key -> ExpectedPosition position -> [event] -> m (Either (EventWriteError position) EventVersion)

Instances

Instances details

Contravariant (EventStoreWriter key position m) Source #
Instance details Defined in Eventium.Store.Class Methods contramap :: (a' -> a) -> EventStoreWriter key position m a -> EventStoreWriter key position m a' # (>$) :: b -> EventStoreWriter key position m b -> EventStoreWriter key position m a #

type VersionedEventStoreReader (m :: Type -> Type) event = EventStoreReader UUID EventVersion m (VersionedStreamEvent event) Source #

type GlobalEventStoreReader (m :: Type -> Type) event = EventStoreReader () SequenceNumber m (GlobalStreamEvent event) Source #

type VersionedEventStoreWriter = EventStoreWriter UUID EventVersion Source #

data StreamEvent key position event Source #

An event along with the key for the event stream it is from and its position in that event stream.

Constructors

StreamEvent
Fields streamEventKey :: !key streamEventPosition :: !position streamEventEvent :: !event

Instances

Instances details

Foldable (StreamEvent key position) Source #
Instance details Defined in Eventium.Store.Class Methods fold :: Monoid m => StreamEvent key position m -> m # foldMap :: Monoid m => (a -> m) -> StreamEvent key position a -> m # foldMap' :: Monoid m => (a -> m) -> StreamEvent key position a -> m # foldr :: (a -> b -> b) -> b -> StreamEvent key position a -> b # foldr' :: (a -> b -> b) -> b -> StreamEvent key position a -> b # foldl :: (b -> a -> b) -> b -> StreamEvent key position a -> b # foldl' :: (b -> a -> b) -> b -> StreamEvent key position a -> b # foldr1 :: (a -> a -> a) -> StreamEvent key position a -> a # foldl1 :: (a -> a -> a) -> StreamEvent key position a -> a # toList :: StreamEvent key position a -> [a] # null :: StreamEvent key position a -> Bool # length :: StreamEvent key position a -> Int # elem :: Eq a => a -> StreamEvent key position a -> Bool # maximum :: Ord a => StreamEvent key position a -> a # minimum :: Ord a => StreamEvent key position a -> a # sum :: Num a => StreamEvent key position a -> a # product :: Num a => StreamEvent key position a -> a #
Traversable (StreamEvent key position) Source #
Instance details Defined in Eventium.Store.Class Methods traverse :: Applicative f => (a -> f b) -> StreamEvent key position a -> f (StreamEvent key position b) # sequenceA :: Applicative f => StreamEvent key position (f a) -> f (StreamEvent key position a) # mapM :: Monad m => (a -> m b) -> StreamEvent key position a -> m (StreamEvent key position b) # sequence :: Monad m => StreamEvent key position (m a) -> m (StreamEvent key position a) #
Functor (StreamEvent key position) Source #
Instance details Defined in Eventium.Store.Class Methods fmap :: (a -> b) -> StreamEvent key position a -> StreamEvent key position b # (<$) :: a -> StreamEvent key position b -> StreamEvent key position a #
(Show key, Show position, Show event) => Show (StreamEvent key position event) Source #
Instance details Defined in Eventium.Store.Class Methods showsPrec :: Int -> StreamEvent key position event -> ShowS # show :: StreamEvent key position event -> String # showList :: [StreamEvent key position event] -> ShowS #
(Eq key, Eq position, Eq event) => Eq (StreamEvent key position event) Source #
Instance details Defined in Eventium.Store.Class Methods (==) :: StreamEvent key position event -> StreamEvent key position event -> Bool # (/=) :: StreamEvent key position event -> StreamEvent key position event -> Bool #

type VersionedStreamEvent event = StreamEvent UUID EventVersion event Source #

type GlobalStreamEvent event = StreamEvent () SequenceNumber (VersionedStreamEvent event) Source #

data ExpectedPosition position Source #

ExpectedPosition is used to assert the event stream is at a certain position. This is used when multiple writers are concurrently writing to the event store. If the expected position is incorrect, then storing fails.

Constructors

AnyPosition	Used when the writer doesn't care what position the stream is at.
NoStream	The stream shouldn't exist yet.
StreamExists	The stream should already exist.
ExactPosition position	Used to assert the stream is at a particular position.

Instances

Instances details

Show position => Show (ExpectedPosition position) Source #
Instance details Defined in Eventium.Store.Class Methods showsPrec :: Int -> ExpectedPosition position -> ShowS # show :: ExpectedPosition position -> String # showList :: [ExpectedPosition position] -> ShowS #
Eq position => Eq (ExpectedPosition position) Source #
Instance details Defined in Eventium.Store.Class Methods (==) :: ExpectedPosition position -> ExpectedPosition position -> Bool # (/=) :: ExpectedPosition position -> ExpectedPosition position -> Bool #

newtype EventWriteError position Source #

Constructors

EventStreamNotAtExpectedVersion position

Instances

Instances details

Show position => Show (EventWriteError position) Source #
Instance details Defined in Eventium.Store.Class Methods showsPrec :: Int -> EventWriteError position -> ShowS # show :: EventWriteError position -> String # showList :: [EventWriteError position] -> ShowS #
Eq position => Eq (EventWriteError position) Source #
Instance details Defined in Eventium.Store.Class Methods (==) :: EventWriteError position -> EventWriteError position -> Bool # (/=) :: EventWriteError position -> EventWriteError position -> Bool #

runEventStoreReaderUsing :: (Monad m, Monad mstore) => (forall a. mstore a -> m a) -> EventStoreReader key position mstore event -> EventStoreReader key position m event Source #

Changes the monad an EventStoreReader runs in. This is useful to run event stores in another Monad while forgetting the original Monad.

runEventStoreWriterUsing :: (Monad m, Monad mstore) => (forall a. mstore a -> m a) -> EventStoreWriter key posirion mstore event -> EventStoreWriter key posirion m event Source #

Analog of runEventStoreReaderUsing for a EventStoreWriter.

module Eventium.Store.Queries

Serialization

serializedEventStoreReader :: forall (m :: Type -> Type) event serialized key position. Monad m => Serializer event serialized -> EventStoreReader key position m serialized -> EventStoreReader key position m event Source #

Wraps an EventStoreReader and transparently serializes/deserializes events for you. Note that in this implementation deserialization errors are simply ignored (the event is not returned).

serializedVersionedEventStoreReader :: forall (m :: Type -> Type) event serialized. Monad m => Serializer event serialized -> VersionedEventStoreReader m serialized -> VersionedEventStoreReader m event Source #

Convenience wrapper around serializedEventStoreReader for VersionedEventStoreReader.

serializedGlobalEventStoreReader :: forall (m :: Type -> Type) event serialized. Monad m => Serializer event serialized -> GlobalEventStoreReader m serialized -> GlobalEventStoreReader m event Source #

Convenience wrapper around serializedEventStoreReader for GlobalEventStoreReader.

serializedEventStoreWriter :: forall (m :: Type -> Type) event serialized key position. Monad m => Serializer event serialized -> EventStoreWriter key position m serialized -> EventStoreWriter key position m event Source #

Like serializedEventStoreReader but for an EventStoreWriter. Note that EventStoreWriter is an instance of Contravariant, so you can just use contramap serialize instead of this function.

Utility types

newtype EventVersion Source #

Event versions are a strictly increasing series of integers for each projection. They allow us to order the events when they are replayed, and they also help as a concurrency check in a multi-threaded environment so services modifying the projection can be sure the projection didn't change during their execution.

Constructors

EventVersion
Fields unEventVersion :: Int

Instances

Instances details

FromJSON EventVersion Source #
Instance details Defined in Eventium.Store.Class Methods parseJSON :: Value -> Parser EventVersion # parseJSONList :: Value -> Parser [EventVersion] # omittedField :: Maybe EventVersion #
ToJSON EventVersion Source #
Instance details Defined in Eventium.Store.Class Methods toJSON :: EventVersion -> Value # toEncoding :: EventVersion -> Encoding # toJSONList :: [EventVersion] -> Value # toEncodingList :: [EventVersion] -> Encoding # omitField :: EventVersion -> Bool #
Enum EventVersion Source #
Instance details Defined in Eventium.Store.Class Methods succ :: EventVersion -> EventVersion # pred :: EventVersion -> EventVersion # toEnum :: Int -> EventVersion # fromEnum :: EventVersion -> Int # enumFrom :: EventVersion -> [EventVersion] # enumFromThen :: EventVersion -> EventVersion -> [EventVersion] # enumFromTo :: EventVersion -> EventVersion -> [EventVersion] # enumFromThenTo :: EventVersion -> EventVersion -> EventVersion -> [EventVersion] #
Num EventVersion Source #
Instance details Defined in Eventium.Store.Class Methods (+) :: EventVersion -> EventVersion -> EventVersion # (-) :: EventVersion -> EventVersion -> EventVersion # (*) :: EventVersion -> EventVersion -> EventVersion # negate :: EventVersion -> EventVersion # abs :: EventVersion -> EventVersion # signum :: EventVersion -> EventVersion # fromInteger :: Integer -> EventVersion #
Read EventVersion Source #
Instance details Defined in Eventium.Store.Class Methods readsPrec :: Int -> ReadS EventVersion # readList :: ReadS [EventVersion] # readPrec :: ReadPrec EventVersion # readListPrec :: ReadPrec [EventVersion] #
Show EventVersion Source #
Instance details Defined in Eventium.Store.Class Methods showsPrec :: Int -> EventVersion -> ShowS # show :: EventVersion -> String # showList :: [EventVersion] -> ShowS #
Eq EventVersion Source #
Instance details Defined in Eventium.Store.Class Methods (==) :: EventVersion -> EventVersion -> Bool # (/=) :: EventVersion -> EventVersion -> Bool #
Ord EventVersion Source #
Instance details Defined in Eventium.Store.Class Methods compare :: EventVersion -> EventVersion -> Ordering # (<) :: EventVersion -> EventVersion -> Bool # (<=) :: EventVersion -> EventVersion -> Bool # (>) :: EventVersion -> EventVersion -> Bool # (>=) :: EventVersion -> EventVersion -> Bool # max :: EventVersion -> EventVersion -> EventVersion # min :: EventVersion -> EventVersion -> EventVersion #

newtype SequenceNumber Source #

The sequence number gives us a global ordering of events in a particular event store. Using sequence numbers is not strictly necessary for an event sourcing and CQRS system, but it makes it way easier to replay events consistently without having to use distributed transactions in an event bus. In SQL-based event stores, they are also very cheap to create.

Constructors

SequenceNumber
Fields unSequenceNumber :: Int

Instances

Instances details

FromJSON SequenceNumber Source #
Instance details Defined in Eventium.Store.Class Methods parseJSON :: Value -> Parser SequenceNumber # parseJSONList :: Value -> Parser [SequenceNumber] # omittedField :: Maybe SequenceNumber #
ToJSON SequenceNumber Source #
Instance details Defined in Eventium.Store.Class Methods toJSON :: SequenceNumber -> Value # toEncoding :: SequenceNumber -> Encoding # toJSONList :: [SequenceNumber] -> Value # toEncodingList :: [SequenceNumber] -> Encoding # omitField :: SequenceNumber -> Bool #
Enum SequenceNumber Source #
Instance details Defined in Eventium.Store.Class Methods succ :: SequenceNumber -> SequenceNumber # pred :: SequenceNumber -> SequenceNumber # toEnum :: Int -> SequenceNumber # fromEnum :: SequenceNumber -> Int # enumFrom :: SequenceNumber -> [SequenceNumber] # enumFromThen :: SequenceNumber -> SequenceNumber -> [SequenceNumber] # enumFromTo :: SequenceNumber -> SequenceNumber -> [SequenceNumber] # enumFromThenTo :: SequenceNumber -> SequenceNumber -> SequenceNumber -> [SequenceNumber] #
Num SequenceNumber Source #
Instance details Defined in Eventium.Store.Class Methods (+) :: SequenceNumber -> SequenceNumber -> SequenceNumber # (-) :: SequenceNumber -> SequenceNumber -> SequenceNumber # (*) :: SequenceNumber -> SequenceNumber -> SequenceNumber # negate :: SequenceNumber -> SequenceNumber # abs :: SequenceNumber -> SequenceNumber # signum :: SequenceNumber -> SequenceNumber # fromInteger :: Integer -> SequenceNumber #
Read SequenceNumber Source #
Instance details Defined in Eventium.Store.Class Methods readsPrec :: Int -> ReadS SequenceNumber # readList :: ReadS [SequenceNumber] # readPrec :: ReadPrec SequenceNumber # readListPrec :: ReadPrec [SequenceNumber] #
Show SequenceNumber Source #
Instance details Defined in Eventium.Store.Class Methods showsPrec :: Int -> SequenceNumber -> ShowS # show :: SequenceNumber -> String # showList :: [SequenceNumber] -> ShowS #
Eq SequenceNumber Source #
Instance details Defined in Eventium.Store.Class Methods (==) :: SequenceNumber -> SequenceNumber -> Bool # (/=) :: SequenceNumber -> SequenceNumber -> Bool #
Ord SequenceNumber Source #
Instance details Defined in Eventium.Store.Class Methods compare :: SequenceNumber -> SequenceNumber -> Ordering # (<) :: SequenceNumber -> SequenceNumber -> Bool # (<=) :: SequenceNumber -> SequenceNumber -> Bool # (>) :: SequenceNumber -> SequenceNumber -> Bool # (>=) :: SequenceNumber -> SequenceNumber -> Bool # max :: SequenceNumber -> SequenceNumber -> SequenceNumber # min :: SequenceNumber -> SequenceNumber -> SequenceNumber #
FromHttpApiData SequenceNumber Source #
Instance details Defined in Eventium.Store.Class Methods parseUrlPiece :: Text -> Either Text SequenceNumber # parseHeader :: ByteString -> Either Text SequenceNumber # parseQueryParam :: Text -> Either Text SequenceNumber #
ToHttpApiData SequenceNumber Source #
Instance details Defined in Eventium.Store.Class Methods toUrlPiece :: SequenceNumber -> Text # toEncodedUrlPiece :: SequenceNumber -> Builder # toHeader :: SequenceNumber -> ByteString # toQueryParam :: SequenceNumber -> Text # toEncodedQueryParam :: SequenceNumber -> Builder #
PathPiece SequenceNumber Source #
Instance details Defined in Eventium.Store.Class Methods fromPathPiece :: Text -> Maybe SequenceNumber # toPathPiece :: SequenceNumber -> Text #

Utility functions

transactionalExpectedWriteHelper :: (Monad m, Ord position, Num position) => (key -> m position) -> (key -> [event] -> m EventVersion) -> key -> ExpectedPosition position -> [event] -> m (Either (EventWriteError position) EventVersion) Source #

Helper to create storeEventsRaw given a function to get the latest stream version and a function to write to the event store. **NOTE**: This only works if the monad m is transactional.