HsLua.Marshalling.Peek

Types for unmarshalling of values from Lua.

Documentation

type Peeker e a = StackIndex -> Peek e a

Function to retrieve a value from Lua's stack.

runPeeker :: Peeker e a -> StackIndex -> LuaE e (Result a)

Runs the peeker function.

data Result a

Record to keep track of failure contexts while retrieving objects from the Lua stack.

Constructors

Success a

Failure ByteString [Name]

Error message and stack of contexts

Instances

Monad Result

Defined in HsLua.Marshalling.Peek

Methods

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

(>>) :: Result a -> Result b -> Result b

return :: a -> Result a

Functor Result

Defined in HsLua.Marshalling.Peek

Methods

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

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

Applicative Result

Defined in HsLua.Marshalling.Peek

Methods

pure :: a -> Result a

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

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

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

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

Alternative Result

Defined in HsLua.Marshalling.Peek

Methods

empty :: Result a

(<|>) :: Result a -> Result a -> Result a

some :: Result a -> Result [a]

many :: Result a -> Result [a]

Eq a => Eq (Result a)

Defined in HsLua.Marshalling.Peek

Methods

(==) :: Result a -> Result a -> Bool

(/=) :: Result a -> Result a -> Bool

Show a => Show (Result a)

Defined in HsLua.Marshalling.Peek

Methods

showsPrec :: Int -> Result a -> ShowS

show :: Result a -> String

showList :: [Result a] -> ShowS

isFailure :: Result a -> Bool

Returns True iff the peek result is a Failure.

failure :: ByteString -> Result a

Create a peek failure record from an error message.

force :: LuaError e => Result a -> LuaE e a

Force creation of an unwrapped result, throwing an exception if that's not possible.

retrieving :: Name -> Peek e a -> Peek e a

Add context information to the peek traceback stack.

resultToEither :: Result a -> Either String a

Converts a Result into an Either, where Left holds the reportable string in case of an failure.

toPeeker :: LuaError e => (StackIndex -> LuaE e a) -> Peeker e a

Converts an old peek funtion to a Peeker.

Lua peek monad

newtype Peek e a

Lua operation with an additional failure mode that can stack errors from different contexts; errors are not based on exceptions).

Constructors

Peek

Fields

• runPeek :: LuaE e (Result a)

Instances

Monad (Peek e)

Defined in HsLua.Marshalling.Peek

Methods

(>>=) :: Peek e a -> (a -> Peek e b) -> Peek e b

(>>) :: Peek e a -> Peek e b -> Peek e b

return :: a -> Peek e a

Functor (Peek e)

Defined in HsLua.Marshalling.Peek

Methods

fmap :: (a -> b) -> Peek e a -> Peek e b

(<$) :: a -> Peek e b -> Peek e a

MonadFail (Peek e)

Defined in HsLua.Marshalling.Peek

Methods

fail :: String -> Peek e a

Applicative (Peek e)

Defined in HsLua.Marshalling.Peek

Methods

pure :: a -> Peek e a

(<*>) :: Peek e (a -> b) -> Peek e a -> Peek e b

liftA2 :: (a -> b -> c) -> Peek e a -> Peek e b -> Peek e c

(*>) :: Peek e a -> Peek e b -> Peek e b

(<*) :: Peek e a -> Peek e b -> Peek e a

Alternative (Peek e)

Defined in HsLua.Marshalling.Peek

Methods

empty :: Peek e a

(<|>) :: Peek e a -> Peek e a -> Peek e a

some :: Peek e a -> Peek e [a]

many :: Peek e a -> Peek e [a]

forcePeek :: LuaError e => Peek e a -> LuaE e a

Converts a Peek action into a LuaE action, throwing an exception in case of a peek failure.

failPeek :: forall a e. ByteString -> Peek e a

Fails the peek operation.

liftLua :: LuaE e a -> Peek e a

Lifts a Lua operation into the Peek monad.

withContext :: Name -> Peek e a -> Peek e a

Transform the result using the given function.

lastly :: Peek e a -> LuaE e b -> Peek e a

Runs the peek action and Lua action in sequence, even if the peek action fails.

cleanup :: Peek e a -> Peek e a

Runs the peek action, resetting the stack top afterwards. This can be used with peek actions that might otherwise leave elements on the stack in case of a failure.