Safe Haskell	Safe-Inferred
Language	Haskell2010

Language.Souffle.Marshal

Description

This module exposes a uniform interface to marshal values to and from Souffle Datalog. This is done via the Marshal typeclass. Also, a mechanism is exposed for generically deriving marshalling and unmarshalling code for simple product types.

Synopsis

class Marshal a where
- push :: MonadPush m => a -> m ()
- pop :: MonadPop m => m a
class Monad m => MonadPush m where
- pushInt32 :: Int32 -> m ()
- pushUInt32 :: Word32 -> m ()
- pushFloat :: Float -> m ()
- pushString :: String -> m ()
- pushText :: Text -> m ()
class Monad m => MonadPop m where
- popInt32 :: m Int32
- popUInt32 :: m Word32
- popFloat :: m Float
- popString :: m String
- popText :: m Text
type family SimpleProduct a where ...

Documentation

class Marshal a where Source #

A typeclass for providing a uniform API to marshal/unmarshal values between Haskell and Souffle datalog.

The marshalling is done via a stack-based approach, where elements are pushed/popped one by one. You need to make sure that the marshalling of values happens in the correct order or unexpected things might happen (including crashes). Pushing and popping of fields should happen in the same order (from left to right, as defined in Datalog). The ordering of how nested products are serialized is the same as when the fields of the nested product types are inlined into the parent type.

Generic implementations for push and pop that perform the previously described behavior are available. This makes it possible to write very succinct code:

data Edge = Edge String String deriving Generic

instance Marshal Edge

Minimal complete definition

Nothing

Methods

push :: MonadPush m => a -> m () Source #

Marshals a value to the datalog side.

default push :: (Generic a, SimpleProduct a, GMarshal (Rep a), MonadPush m) => a -> m () Source #

pop :: MonadPop m => m a Source #

Unmarshals a value from the datalog side.

default pop :: (Generic a, SimpleProduct a, GMarshal (Rep a), MonadPop m) => m a Source #

Instances

Instances details

Marshal Int32 Source #
Instance details Defined in Language.Souffle.Marshal Methods push :: MonadPush m => Int32 -> m () Source # pop :: MonadPop m => m Int32 Source #
Marshal Word32 Source #
Instance details Defined in Language.Souffle.Marshal Methods push :: MonadPush m => Word32 -> m () Source # pop :: MonadPop m => m Word32 Source #
Marshal Text Source #
Instance details Defined in Language.Souffle.Marshal Methods push :: MonadPush m => Text -> m () Source # pop :: MonadPop m => m Text Source #
Marshal Text Source #
Instance details Defined in Language.Souffle.Marshal Methods push :: MonadPush m => Text -> m () Source # pop :: MonadPop m => m Text Source #
Marshal String Source #
Instance details Defined in Language.Souffle.Marshal Methods push :: MonadPush m => String -> m () Source # pop :: MonadPop m => m String Source #
Marshal Float Source #
Instance details Defined in Language.Souffle.Marshal Methods push :: MonadPush m => Float -> m () Source # pop :: MonadPop m => m Float Source #
Marshal fact => Marshal (FactOptions fact name dir) Source #
Instance details Defined in Language.Souffle.Class Methods push :: MonadPush m => FactOptions fact name dir -> m () Source # pop :: MonadPop m => m (FactOptions fact name dir) Source #

class Monad m => MonadPush m where Source #

A typeclass for serializing primitive values from Haskell to Datalog.

This typeclass is only used internally and subject to change.