Language.Souffle.Interpreted

This module provides an implementation for the MonadSouffle typeclass defined in Language.Souffle.Class. It makes use of the Souffle interpreter and CSV files to offer an implementation optimized for quick development speed compared to Language.Souffle.Compiled.

It is however much slower so users are advised to switch over to the compiled alternative once the prototyping phase is finished.

Documentation

class Program a where

A typeclass for describing a datalog program.

Example usage (assuming the program was generated from path.dl and contains 2 facts: Edge and Reachable):

data Path = Path  -- Handle for the datalog program

instance Program Path where
  type ProgramFacts Path = '[Edge, Reachable]
  programName = const "path"

Associated Types

type ProgramFacts a :: [Type]

A type level list of facts that belong to this program. This list is used to check that only known facts are added to a program.

Methods

programName :: a -> String

Function for obtaining the name of a Datalog program. This has to be the same as the name of the .dl file (minus the extension).

Instances

KnownSymbol progName => Program (ProgramOptions prog progName facts)

Defined in Language.Souffle.Class

Associated Types

type ProgramFacts (ProgramOptions prog progName facts) :: [Type]

Methods

programName :: ProgramOptions prog progName facts -> String

newtype ProgramOptions prog progName facts

A helper data type, used in combination with the DerivingVia extension to automatically generate code to bind Haskell to a Souffle Datalog program.

The following is an example how to bind to a Datalog program "path" (saved as path.dl / path.cpp), that uses two facts called "edge" and "reachable" (represented with the Edge and Reachable types):

data Path = Path
  deriving Souffle.Program
  via Souffle.ProgramOptions Path "path" '[Edge, Reachable]

See also: FactOptions.

Constructors

ProgramOptions prog

Instances

KnownSymbol progName => Program (ProgramOptions prog progName facts)

Defined in Language.Souffle.Class

Associated Types

type ProgramFacts (ProgramOptions prog progName facts) :: [Type]

Methods

programName :: ProgramOptions prog progName facts -> String

type ProgramFacts (ProgramOptions prog progName facts)

Defined in Language.Souffle.Class

type ProgramFacts (ProgramOptions prog progName facts) = facts

class Marshal a => Fact a where

A typeclass for data types representing a fact in datalog.

Example usage:

instance Fact Edge where
  type FactDirection Edge = 'Input
  factName = const "edge"

Associated Types

type FactDirection a :: Direction

The direction or "mode" a fact can be used in. This is used to perform compile-time checks that a fact is only used in valid situations. For more information, see the Direction type.

Methods

factName :: Proxy a -> String

Function for obtaining the name of a fact (has to be the same as described in the Datalog program).

It uses a Proxy to select the correct instance.

Instances

(Marshal fact, KnownSymbol factName) => Fact (FactOptions fact factName dir)

Defined in Language.Souffle.Class

Associated Types

type FactDirection (FactOptions fact factName dir) :: Direction

Methods

factName :: Proxy (FactOptions fact factName dir) -> String

newtype FactOptions fact factName dir

A helper data type, used in combination with the DerivingVia extension to automatically generate code to bind a Haskell datatype to a Souffle Datalog fact.

The following is an example how to bind to a Datalog fact "edge" that contains two symbols (strings in Haskell) that is an input (from the Datalog point of view):

data Edge = Edge String String
  deriving (Eq, Show, Generic)
  deriving anyclass Souffle.Marshal
  deriving Souffle.Fact
  via Souffle.FactOptions Edge "edge" 'Souffle.Input

See also: ProgramOptions.

Constructors

FactOptions fact

Instances

(Marshal fact, KnownSymbol factName) => Fact (FactOptions fact factName dir)

Defined in Language.Souffle.Class

Associated Types

type FactDirection (FactOptions fact factName dir) :: Direction

Methods

factName :: Proxy (FactOptions fact factName dir) -> String

Marshal fact => Marshal (FactOptions fact name dir)

Defined in Language.Souffle.Class

Methods

push :: MonadPush m => FactOptions fact name dir -> m ()

pop :: MonadPop m => m (FactOptions fact name dir)

type FactDirection (FactOptions fact factName dir)

Defined in Language.Souffle.Class

type FactDirection (FactOptions fact factName dir) = dir

class Marshal a where

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 ()

Marshals a value to the datalog side.

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

pop :: MonadPop m => m a

Unmarshals a value from the datalog side.

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

Instances

Marshal Int32

Defined in Language.Souffle.Marshal

Methods

push :: MonadPush m => Int32 -> m ()

pop :: MonadPop m => m Int32

Marshal Word32

Defined in Language.Souffle.Marshal

Methods

push :: MonadPush m => Word32 -> m ()

pop :: MonadPop m => m Word32

Marshal Text

Defined in Language.Souffle.Marshal

Methods

push :: MonadPush m => Text -> m ()

pop :: MonadPop m => m Text

Marshal Text

Defined in Language.Souffle.Marshal

Methods

push :: MonadPush m => Text -> m ()

pop :: MonadPop m => m Text

Marshal String

Defined in Language.Souffle.Marshal

Methods

push :: MonadPush m => String -> m ()

pop :: MonadPop m => m String

Marshal Float

Defined in Language.Souffle.Marshal

Methods

push :: MonadPush m => Float -> m ()

pop :: MonadPop m => m Float

Marshal fact => Marshal (FactOptions fact name dir)

Defined in Language.Souffle.Class

Methods

push :: MonadPush m => FactOptions fact name dir -> m ()

pop :: MonadPop m => m (FactOptions fact name dir)

data Direction

A datatype describing which operations a certain fact supports. The direction is from the datalog perspective, so that it aligns with ".decl" statements in Souffle.

Constructors

Input

Fact can only be stored in Datalog (using addFact/addFacts).

Output

Fact can only be read from Datalog (using getFacts/findFact).

InputOutput

Fact supports both reading from / writing to Datalog.

Internal

Supports neither reading from / writing to Datalog. This is used for facts that are only visible inside Datalog itself.

type family ContainsInputFact prog fact where ...

A helper type family for checking if a specific Souffle Program contains a certain Fact. Additionally, it also checks if the fact is marked as either Input or InputOutput. This constraint will generate a user-friendly type error if these conditions are not met.

Equations

ContainsInputFact prog fact = (ContainsFact prog fact, IsInput fact (FactDirection fact))

type family ContainsOutputFact prog fact where ...

A helper type family for checking if a specific Souffle Program contains a certain Fact. Additionally, it also checks if the fact is marked as either Output or InputOutput. This constraint will generate a user-friendly type error if these conditions are not met.

Equations

ContainsOutputFact prog fact = (ContainsFact prog fact, IsOutput fact (FactDirection fact))

data Config

A helper data type for storing the configurable settings of the interpreter.

• cfgDatalogDir: The directory where the datalog file(s) are located.
• cfgSouffleBin: The name of the souffle binary. Has to be available in $PATH or an absolute path needs to be provided. Note: Passing in Nothing will fail to start up the interpreter in the init function.
• cfgFactDir: The directory where the initial input fact file(s) can be found if present. If Nothing, then a temporary directory will be used, during the souffle session.
• cfgOutputDir: The directory where the output fact file(s) are created. If Nothing, it will be part of the temporary directory.

Constructors

Config

Fields

• cfgDatalogDir :: FilePath
• cfgSouffleBin :: Maybe FilePath
• cfgFactDir :: Maybe FilePath
• cfgOutputDir :: Maybe FilePath

Instances

Show Config

Defined in Language.Souffle.Interpreted

Methods

showsPrec :: Int -> Config -> ShowS

show :: Config -> String

showList :: [Config] -> ShowS

data Handle prog

A datatype representing a handle to a datalog program. The type parameter is used for keeping track of which program type the handle belongs to for additional type safety.

data SouffleM a

A monad for executing Souffle-related actions in.

Instances

MonadIO SouffleM

Defined in Language.Souffle.Interpreted

Methods

liftIO :: IO a -> SouffleM a

Applicative SouffleM

Defined in Language.Souffle.Interpreted

Methods

pure :: a -> SouffleM a

(<*>) :: SouffleM (a -> b) -> SouffleM a -> SouffleM b

liftA2 :: (a -> b -> c) -> SouffleM a -> SouffleM b -> SouffleM c

(*>) :: SouffleM a -> SouffleM b -> SouffleM b

(<*) :: SouffleM a -> SouffleM b -> SouffleM a

Functor SouffleM

Defined in Language.Souffle.Interpreted

Methods

fmap :: (a -> b) -> SouffleM a -> SouffleM b

(<$) :: a -> SouffleM b -> SouffleM a

Monad SouffleM

Defined in Language.Souffle.Interpreted

Methods

(>>=) :: SouffleM a -> (a -> SouffleM b) -> SouffleM b

(>>) :: SouffleM a -> SouffleM b -> SouffleM b

return :: a -> SouffleM a

MonadSouffle SouffleM

Defined in Language.Souffle.Interpreted

Associated Types

type Handler SouffleM :: Type -> Type

type CollectFacts SouffleM c

type SubmitFacts SouffleM a

Methods

run :: Handler SouffleM prog -> SouffleM ()

setNumThreads :: Handler SouffleM prog -> Word64 -> SouffleM ()

getNumThreads :: Handler SouffleM prog -> SouffleM Word64

getFacts :: (Fact a, ContainsOutputFact prog a, CollectFacts SouffleM c) => Handler SouffleM prog -> SouffleM (c a)

findFact :: (Fact a, ContainsOutputFact prog a, Eq a, SubmitFacts SouffleM a) => Handler SouffleM prog -> a -> SouffleM (Maybe a)

addFact :: (Fact a, ContainsInputFact prog a, SubmitFacts SouffleM a) => Handler SouffleM prog -> a -> SouffleM ()

addFacts :: (Foldable t, Fact a, ContainsInputFact prog a, SubmitFacts SouffleM a) => Handler SouffleM prog -> t a -> SouffleM ()

Monoid a => Monoid (SouffleM a)

Defined in Language.Souffle.Interpreted

Methods

mempty :: SouffleM a

mappend :: SouffleM a -> SouffleM a -> SouffleM a

mconcat :: [SouffleM a] -> SouffleM a

Semigroup a => Semigroup (SouffleM a)

Defined in Language.Souffle.Interpreted

Methods

(<>) :: SouffleM a -> SouffleM a -> SouffleM a

sconcat :: NonEmpty (SouffleM a) -> SouffleM a

stimes :: Integral b => b -> SouffleM a -> SouffleM a

type Handler SouffleM

Defined in Language.Souffle.Interpreted

type Handler SouffleM = Handle

type CollectFacts SouffleM c

Defined in Language.Souffle.Interpreted

type CollectFacts SouffleM c

type SubmitFacts SouffleM _1

Defined in Language.Souffle.Interpreted

type SubmitFacts SouffleM _1 = ()

class Monad m => MonadSouffle m where

A mtl-style typeclass for Souffle-related actions.

Associated Types

type Handler m :: Type -> Type

Represents a handle for interacting with a Souffle program.

The handle is used in all other functions of this typeclass to perform Souffle-related actions.

type CollectFacts m (c :: Type -> Type) :: Constraint

Helper associated type constraint that allows collecting facts from Souffle in a list or vector. Only used internally.

type SubmitFacts m (a :: Type) :: Constraint

Helper associated type constraint that allows submitting facts to Souffle. Only used internally.

Methods

run :: Handler m prog -> m ()

Runs the Souffle program.

setNumThreads :: Handler m prog -> Word64 -> m ()

Sets the number of CPU cores this Souffle program should use.

getNumThreads :: Handler m prog -> m Word64

Gets the number of CPU cores this Souffle program should use.

getFacts :: (Fact a, ContainsOutputFact prog a, CollectFacts m c) => Handler m prog -> m (c a)

Returns all facts of a program. This function makes use of type inference to select the type of fact to return.

findFact :: (Fact a, ContainsOutputFact prog a, Eq a, SubmitFacts m a) => Handler m prog -> a -> m (Maybe a)

Searches for a fact in a program. Returns Nothing if no matching fact was found; otherwise Just the fact.

Conceptually equivalent to List.find (== fact) <$> getFacts prog, but this operation can be implemented much faster.

addFact :: (Fact a, ContainsInputFact prog a, SubmitFacts m a) => Handler m prog -> a -> m ()

Adds a fact to the program.

addFacts :: (Foldable t, Fact a, ContainsInputFact prog a, SubmitFacts m a) => Handler m prog -> t a -> m ()

Adds multiple facts to the program. This function could be implemented in terms of addFact, but this is done as a minor optimization.

Instances

MonadSouffle SouffleM

Defined in Language.Souffle.Compiled

Associated Types

type Handler SouffleM :: Type -> Type

type CollectFacts SouffleM c

type SubmitFacts SouffleM a

Methods

run :: Handler SouffleM prog -> SouffleM ()

setNumThreads :: Handler SouffleM prog -> Word64 -> SouffleM ()

getNumThreads :: Handler SouffleM prog -> SouffleM Word64

getFacts :: (Fact a, ContainsOutputFact prog a, CollectFacts SouffleM c) => Handler SouffleM prog -> SouffleM (c a)

findFact :: (Fact a, ContainsOutputFact prog a, Eq a, SubmitFacts SouffleM a) => Handler SouffleM prog -> a -> SouffleM (Maybe a)

addFact :: (Fact a, ContainsInputFact prog a, SubmitFacts SouffleM a) => Handler SouffleM prog -> a -> SouffleM ()

addFacts :: (Foldable t, Fact a, ContainsInputFact prog a, SubmitFacts SouffleM a) => Handler SouffleM prog -> t a -> SouffleM ()

MonadSouffle SouffleM

Defined in Language.Souffle.Interpreted

Associated Types

type Handler SouffleM :: Type -> Type

type CollectFacts SouffleM c

type SubmitFacts SouffleM a

Methods

run :: Handler SouffleM prog -> SouffleM ()

setNumThreads :: Handler SouffleM prog -> Word64 -> SouffleM ()

getNumThreads :: Handler SouffleM prog -> SouffleM Word64

getFacts :: (Fact a, ContainsOutputFact prog a, CollectFacts SouffleM c) => Handler SouffleM prog -> SouffleM (c a)

findFact :: (Fact a, ContainsOutputFact prog a, Eq a, SubmitFacts SouffleM a) => Handler SouffleM prog -> a -> SouffleM (Maybe a)

addFact :: (Fact a, ContainsInputFact prog a, SubmitFacts SouffleM a) => Handler SouffleM prog -> a -> SouffleM ()

addFacts :: (Foldable t, Fact a, ContainsInputFact prog a, SubmitFacts SouffleM a) => Handler SouffleM prog -> t a -> SouffleM ()

MonadSouffle m => MonadSouffle (ExceptT e m)

Defined in Language.Souffle.Class

Associated Types

type Handler (ExceptT e m) :: Type -> Type

type CollectFacts (ExceptT e m) c

type SubmitFacts (ExceptT e m) a

Methods

run :: Handler (ExceptT e m) prog -> ExceptT e m ()

setNumThreads :: Handler (ExceptT e m) prog -> Word64 -> ExceptT e m ()

getNumThreads :: Handler (ExceptT e m) prog -> ExceptT e m Word64

getFacts :: (Fact a, ContainsOutputFact prog a, CollectFacts (ExceptT e m) c) => Handler (ExceptT e m) prog -> ExceptT e m (c a)

findFact :: (Fact a, ContainsOutputFact prog a, Eq a, SubmitFacts (ExceptT e m) a) => Handler (ExceptT e m) prog -> a -> ExceptT e m (Maybe a)

addFact :: (Fact a, ContainsInputFact prog a, SubmitFacts (ExceptT e m) a) => Handler (ExceptT e m) prog -> a -> ExceptT e m ()

addFacts :: (Foldable t, Fact a, ContainsInputFact prog a, SubmitFacts (ExceptT e m) a) => Handler (ExceptT e m) prog -> t a -> ExceptT e m ()

MonadSouffle m => MonadSouffle (ReaderT r m)

Defined in Language.Souffle.Class

Associated Types

type Handler (ReaderT r m) :: Type -> Type

type CollectFacts (ReaderT r m) c

type SubmitFacts (ReaderT r m) a

Methods

run :: Handler (ReaderT r m) prog -> ReaderT r m ()

setNumThreads :: Handler (ReaderT r m) prog -> Word64 -> ReaderT r m ()

getNumThreads :: Handler (ReaderT r m) prog -> ReaderT r m Word64

getFacts :: (Fact a, ContainsOutputFact prog a, CollectFacts (ReaderT r m) c) => Handler (ReaderT r m) prog -> ReaderT r m (c a)

findFact :: (Fact a, ContainsOutputFact prog a, Eq a, SubmitFacts (ReaderT r m) a) => Handler (ReaderT r m) prog -> a -> ReaderT r m (Maybe a)

addFact :: (Fact a, ContainsInputFact prog a, SubmitFacts (ReaderT r m) a) => Handler (ReaderT r m) prog -> a -> ReaderT r m ()

addFacts :: (Foldable t, Fact a, ContainsInputFact prog a, SubmitFacts (ReaderT r m) a) => Handler (ReaderT r m) prog -> t a -> ReaderT r m ()

MonadSouffle m => MonadSouffle (StateT s m)

Defined in Language.Souffle.Class

Associated Types

type Handler (StateT s m) :: Type -> Type

type CollectFacts (StateT s m) c

type SubmitFacts (StateT s m) a

Methods

run :: Handler (StateT s m) prog -> StateT s m ()

setNumThreads :: Handler (StateT s m) prog -> Word64 -> StateT s m ()

getNumThreads :: Handler (StateT s m) prog -> StateT s m Word64

getFacts :: (Fact a, ContainsOutputFact prog a, CollectFacts (StateT s m) c) => Handler (StateT s m) prog -> StateT s m (c a)

findFact :: (Fact a, ContainsOutputFact prog a, Eq a, SubmitFacts (StateT s m) a) => Handler (StateT s m) prog -> a -> StateT s m (Maybe a)

addFact :: (Fact a, ContainsInputFact prog a, SubmitFacts (StateT s m) a) => Handler (StateT s m) prog -> a -> StateT s m ()

addFacts :: (Foldable t, Fact a, ContainsInputFact prog a, SubmitFacts (StateT s m) a) => Handler (StateT s m) prog -> t a -> StateT s m ()

MonadSouffle m => MonadSouffle (StateT s m)

Defined in Language.Souffle.Class

Associated Types

type Handler (StateT s m) :: Type -> Type

type CollectFacts (StateT s m) c

type SubmitFacts (StateT s m) a

Methods

run :: Handler (StateT s m) prog -> StateT s m ()

setNumThreads :: Handler (StateT s m) prog -> Word64 -> StateT s m ()

getNumThreads :: Handler (StateT s m) prog -> StateT s m Word64

getFacts :: (Fact a, ContainsOutputFact prog a, CollectFacts (StateT s m) c) => Handler (StateT s m) prog -> StateT s m (c a)

findFact :: (Fact a, ContainsOutputFact prog a, Eq a, SubmitFacts (StateT s m) a) => Handler (StateT s m) prog -> a -> StateT s m (Maybe a)

addFact :: (Fact a, ContainsInputFact prog a, SubmitFacts (StateT s m) a) => Handler (StateT s m) prog -> a -> StateT s m ()

addFacts :: (Foldable t, Fact a, ContainsInputFact prog a, SubmitFacts (StateT s m) a) => Handler (StateT s m) prog -> t a -> StateT s m ()

(Monoid w, MonadSouffle m) => MonadSouffle (WriterT w m)

Defined in Language.Souffle.Class

Associated Types

type Handler (WriterT w m) :: Type -> Type

type CollectFacts (WriterT w m) c

type SubmitFacts (WriterT w m) a

Methods

run :: Handler (WriterT w m) prog -> WriterT w m ()

setNumThreads :: Handler (WriterT w m) prog -> Word64 -> WriterT w m ()

getNumThreads :: Handler (WriterT w m) prog -> WriterT w m Word64

getFacts :: (Fact a, ContainsOutputFact prog a, CollectFacts (WriterT w m) c) => Handler (WriterT w m) prog -> WriterT w m (c a)

findFact :: (Fact a, ContainsOutputFact prog a, Eq a, SubmitFacts (WriterT w m) a) => Handler (WriterT w m) prog -> a -> WriterT w m (Maybe a)

addFact :: (Fact a, ContainsInputFact prog a, SubmitFacts (WriterT w m) a) => Handler (WriterT w m) prog -> a -> WriterT w m ()

addFacts :: (Foldable t, Fact a, ContainsInputFact prog a, SubmitFacts (WriterT w m) a) => Handler (WriterT w m) prog -> t a -> WriterT w m ()

(MonadSouffle m, Monoid w) => MonadSouffle (RWST r w s m)

Defined in Language.Souffle.Class

Associated Types

type Handler (RWST r w s m) :: Type -> Type

type CollectFacts (RWST r w s m) c

type SubmitFacts (RWST r w s m) a

Methods

run :: Handler (RWST r w s m) prog -> RWST r w s m ()

setNumThreads :: Handler (RWST r w s m) prog -> Word64 -> RWST r w s m ()

getNumThreads :: Handler (RWST r w s m) prog -> RWST r w s m Word64

getFacts :: (Fact a, ContainsOutputFact prog a, CollectFacts (RWST r w s m) c) => Handler (RWST r w s m) prog -> RWST r w s m (c a)

findFact :: (Fact a, ContainsOutputFact prog a, Eq a, SubmitFacts (RWST r w s m) a) => Handler (RWST r w s m) prog -> a -> RWST r w s m (Maybe a)

addFact :: (Fact a, ContainsInputFact prog a, SubmitFacts (RWST r w s m) a) => Handler (RWST r w s m) prog -> a -> RWST r w s m ()

addFacts :: (Foldable t, Fact a, ContainsInputFact prog a, SubmitFacts (RWST r w s m) a) => Handler (RWST r w s m) prog -> t a -> RWST r w s m ()

(MonadSouffle m, Monoid w) => MonadSouffle (RWST r w s m)

Defined in Language.Souffle.Class

Associated Types

type Handler (RWST r w s m) :: Type -> Type

type CollectFacts (RWST r w s m) c

type SubmitFacts (RWST r w s m) a

Methods

run :: Handler (RWST r w s m) prog -> RWST r w s m ()

setNumThreads :: Handler (RWST r w s m) prog -> Word64 -> RWST r w s m ()

getNumThreads :: Handler (RWST r w s m) prog -> RWST r w s m Word64

getFacts :: (Fact a, ContainsOutputFact prog a, CollectFacts (RWST r w s m) c) => Handler (RWST r w s m) prog -> RWST r w s m (c a)

findFact :: (Fact a, ContainsOutputFact prog a, Eq a, SubmitFacts (RWST r w s m) a) => Handler (RWST r w s m) prog -> a -> RWST r w s m (Maybe a)

addFact :: (Fact a, ContainsInputFact prog a, SubmitFacts (RWST r w s m) a) => Handler (RWST r w s m) prog -> a -> RWST r w s m ()

addFacts :: (Foldable t, Fact a, ContainsInputFact prog a, SubmitFacts (RWST r w s m) a) => Handler (RWST r w s m) prog -> t a -> RWST r w s m ()

runSouffle :: Program prog => prog -> (Maybe (Handle prog) -> SouffleM a) -> IO a

Initializes and runs a Souffle program with default settings.

The 2nd argument is passed in a handle after initialization of the Souffle program. The handle will contain Nothing if it failed to locate the souffle interpreter executable or if it failed to find the souffle program file. In the successful case it will contain a handle that can be used for performing Souffle related actions using the other functions in this module.

runSouffleWith :: Program prog => Config -> prog -> (Maybe (Handle prog) -> SouffleM a) -> IO a

Initializes and runs a Souffle program with the given interpreter settings.

The 3rd argument is passed in a handle after initialization of the Souffle program. The handle will contain Nothing if it failed to locate the souffle interpreter executable or if it failed to find the souffle program file. In the successful case it will contain a handle that can be used for performing Souffle related actions using the other functions in this module.

If the config settings do not specify a fact or output dir, temporary directories will be created for storing files in. These directories will also be automatically cleaned up at the end of this function.

defaultConfig :: MonadIO m => m Config

Retrieves the default config for the interpreter. These settings can be overridden using record update syntax if needed.

By default, the settings will be configured as follows:

• cfgDatalogDir: Looks at environment variable $DATALOG_DIR, falls back to the current directory if not set.
• cfgSouffleBin: Looks at environment variable $SOUFFLE_BIN, or tries to locate the souffle binary using the which shell command if the variable is not set.
• cfgFactDir: Will make use of a temporary directory.
• cfgOutputDir: Will make use of a temporary directory.

souffleStdOut :: forall prog. Program prog => Handle prog -> SouffleM (Maybe Text)

Returns the handle of stdout from the souffle interpreter.

souffleStdErr :: forall prog. Program prog => Handle prog -> SouffleM (Maybe Text)

Returns the content of stderr from the souffle interpreter.