Copyright	© 2020-2022 Albert Krewinkel
License	MIT
Maintainer	Albert Krewinkel <tarleb+hslua@zeitkraut.de>
Stability	beta
Portability	Portable
Safe Haskell	None
Language	Haskell2010

HsLua.Marshalling.Peek

Contents

Lua peek monad

Description

Types for unmarshalling of values from Lua.

Synopsis

type Peeker e a = StackIndex -> Peek e a
runPeeker :: Peeker e a -> StackIndex -> LuaE e (Result a)
data Result a
- = Success !a
- | Failure ByteString [Name]
isFailure :: Result a -> Bool
failure :: ByteString -> Result a
force :: LuaError e => Result a -> LuaE e a
retrieving :: Name -> Peek e a -> Peek e a
resultToEither :: Result a -> Either String a
toPeeker :: LuaError e => (StackIndex -> LuaE e a) -> Peeker e a
newtype Peek e a = Peek {
- runPeek :: LuaE e (Result a)
}
forcePeek :: LuaError e => Peek e a -> LuaE e a
failPeek :: forall a e. ByteString -> Peek e a
liftLua :: LuaE e a -> Peek e a
withContext :: Name -> Peek e a -> Peek e a
lastly :: Peek e a -> LuaE e b -> Peek e a
cleanup :: Peek e a -> Peek e a

Documentation

type Peeker e a = StackIndex -> Peek e a Source #

Function to retrieve a value from Lua's stack.

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

Runs the peeker function.

data Result a Source #

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

Instances details

Monad Result Source #
Instance details 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 Source #
Instance details Defined in HsLua.Marshalling.Peek Methods fmap :: (a -> b) -> Result a -> Result b # (<$) :: a -> Result b -> Result a #
Applicative Result Source #
Instance details 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 Source #
Instance details 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) Source #
Instance details Defined in HsLua.Marshalling.Peek Methods (==) :: Result a -> Result a -> Bool # (/=) :: Result a -> Result a -> Bool #
Show a => Show (Result a) Source #
Instance details Defined in HsLua.Marshalling.Peek Methods showsPrec :: Int -> Result a -> ShowS # show :: Result a -> String # showList :: [Result a] -> ShowS #

isFailure :: Result a -> Bool Source #

Returns True iff the peek result is a Failure.

failure :: ByteString -> Result a Source #

Create a peek failure record from an error message.

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

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

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

Add context information to the peek traceback stack.

resultToEither :: Result a -> Either String a Source #

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 Source #

Converts an old peek funtion to a Peeker.

Lua peek monad

newtype Peek e a Source #

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

Instances details

Monad (Peek e) Source #
Instance details 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) Source #
Instance details 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) Source #
Instance details Defined in HsLua.Marshalling.Peek Methods fail :: String -> Peek e a #
Applicative (Peek e) Source #
Instance details 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) Source #
Instance details 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 Source #

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 Source #

Fails the peek operation.

liftLua :: LuaE e a -> Peek e a Source #

Lifts a Lua operation into the Peek monad.

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

Transform the result using the given function.

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

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

cleanup :: Peek e a -> Peek e a Source #

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.