HsLua.Core

hslua-core-2.3.2: Bindings to Lua, an embeddable scripting language

Copyright | © 2007–2012 Gracjan Polak; © 2012–2016 Ömer Sinan Ağacan; © 2017-2024 Albert Krewinkel
License | MIT
Maintainer | Albert Krewinkel <tarleb@hslua.org>
Stability | beta
Portability | non-portable (depends on GHC)
Safe Haskell | None
Language | Haskell2010

HsLua.Core

Contents

- Run Lua computations
- Lua Computations
- Lua API types
  - Stack index
  - Number of arguments and return values
  - Table fields
- Lua API
  - Constants and pseudo-indices
  - State manipulation
  - Basic stack manipulation
  - types and type checks
  - access functions (stack → Haskell)
  - Comparison and arithmetic functions
  - push functions (Haskell → stack)
  - get functions (Lua → stack)
  - set functions (stack → Lua)
  - load and call functions (load and run Lua code)
  - Coroutine functions
  - garbage-collection function and options
  - miscellaneous and helper functions
- loading libraries
- Auxiliary library
  - References
  - Registry fields
  - Running with tracebacks
  - Warnings
- Debug interface
- Haskell userdata values
  - Haskell functions and closures
- Error handling
  - Helpers
- Package

Description

Core Lua API. This module provides thin wrappers around the respective functions of the Lua C API. C functions which can throw an error are wrapped such that the error is converted into an ``Exception``. However, memory allocation errors are not caught and will cause the host program to terminate.

Synopsis

- run :: LuaE e a -> IO a
- runWith :: State -> LuaE e a -> IO a
- runEither :: Exception e => LuaE e a -> IO (Either e a)
- data GCManagedState
- newGCManagedState :: IO GCManagedState
- closeGCManagedState :: GCManagedState -> IO ()
- withGCManagedState :: GCManagedState -> LuaE e a -> IO a
- newtype LuaE e a = Lua {
  - unLua :: ReaderT LuaEnvironment IO a
  }
- type Lua a = LuaE Exception a
- unsafeRunWith :: State -> LuaE e a -> IO a
- liftIO :: MonadIO m => IO a -> m a
- state :: LuaE e State
- newtype LuaEnvironment = LuaEnvironment {
  - luaEnvState :: State
  }
- type CFunction = FunPtr PreCFunction
- type PreCFunction = State -> IO NumResults
- newtype Integer = Integer Int64
- newtype Number = Number Double
- newtype StackIndex = StackIndex {
  - fromStackIndex :: CInt
  }
- nthTop :: CInt -> StackIndex
- nthBottom :: CInt -> StackIndex
- nth :: CInt -> StackIndex
- top :: StackIndex
- newtype NumArgs = NumArgs {
  - fromNumArgs :: CInt
  }
- newtype NumResults = NumResults {
  - fromNumResults :: CInt
  }
- newtype Name = Name {
  - fromName :: ByteString
  }
- multret :: NumResults
- registryindex :: StackIndex
- upvalueindex :: StackIndex -> StackIndex
- newtype State = State (Ptr ())
- newstate :: IO State
- close :: State -> IO ()
- absindex :: StackIndex -> LuaE e StackIndex
- gettop :: LuaE e StackIndex
- settop :: StackIndex -> LuaE e ()
- pushvalue :: StackIndex -> LuaE e ()
- copy :: StackIndex -> StackIndex -> LuaE e ()
- insert :: StackIndex -> LuaE e ()
- rotate :: StackIndex -> Int -> LuaE e ()
- pop :: Int -> LuaE e ()
- remove :: StackIndex -> LuaE e ()
- replace :: StackIndex -> LuaE e ()
- checkstack :: Int -> LuaE e Bool
- data Type
  - = TypeNone
  - | TypeNil
  - | TypeBoolean
  - | TypeLightUserdata
  - | TypeNumber
  - | TypeString
  - | TypeTable
  - | TypeFunction
  - | TypeUserdata
  - | TypeThread
- ltype :: StackIndex -> LuaE e Type
- typename :: Type -> LuaE e ByteString
- isboolean :: StackIndex -> LuaE e Bool
- iscfunction :: StackIndex -> LuaE e Bool
- isfunction :: StackIndex -> LuaE e Bool
- isinteger :: StackIndex -> LuaE e Bool
- islightuserdata :: StackIndex -> LuaE e Bool
- isnil :: StackIndex -> LuaE e Bool
- isnone :: StackIndex -> LuaE e Bool
- isnoneornil :: StackIndex -> LuaE e Bool
- isnumber :: StackIndex -> LuaE e Bool
- isstring :: StackIndex -> LuaE e Bool
- istable :: StackIndex -> LuaE e Bool
- isthread :: StackIndex -> LuaE e Bool
- isuserdata :: StackIndex -> LuaE e Bool
- toboolean :: StackIndex -> LuaE e Bool
- tocfunction :: StackIndex -> LuaE e (Maybe CFunction)
- tointeger :: StackIndex -> LuaE e (Maybe Integer)
- tonumber :: StackIndex -> LuaE e (Maybe Number)
- topointer :: StackIndex -> LuaE e (Ptr ())
- tostring :: StackIndex -> LuaE e (Maybe ByteString)
- tothread :: StackIndex -> LuaE e (Maybe State)
- touserdata :: StackIndex -> LuaE e (Maybe (Ptr a))
- rawlen :: StackIndex -> LuaE e Int
- data RelationalOperator
  - = EQ
  - | LT
  - | LE
- compare :: LuaError e => StackIndex -> StackIndex -> RelationalOperator -> LuaE e Bool
- equal :: LuaError e => StackIndex -> StackIndex -> LuaE e Bool
- lessthan :: LuaError e => StackIndex -> StackIndex -> LuaE e Bool
- rawequal :: StackIndex -> StackIndex -> LuaE e Bool
- pushboolean :: Bool -> LuaE e ()
- pushcfunction :: CFunction -> LuaE e ()
- pushcclosure :: CFunction -> NumArgs -> LuaE e ()
- pushinteger :: Integer -> LuaE e ()
- pushlightuserdata :: Ptr a -> LuaE e ()
- pushnil :: LuaE e ()
- pushnumber :: Number -> LuaE e ()
- pushstring :: ByteString -> LuaE e ()
- pushthread :: LuaE e Bool
- getglobal :: LuaError e => Name -> LuaE e Type
- gettable :: LuaError e => StackIndex -> LuaE e Type
- getfield :: LuaError e => StackIndex -> Name -> LuaE e Type
- rawget :: LuaError e => StackIndex -> LuaE e Type
- rawgeti :: LuaError e => StackIndex -> Integer -> LuaE e Type
- createtable :: Int -> Int -> LuaE e ()
- newtable :: LuaE e ()
- newuserdatauv :: Int -> Int -> LuaE e (Ptr ())
- getmetatable :: StackIndex -> LuaE e Bool
- getiuservalue :: StackIndex -> Int -> LuaE e Type
- setglobal :: LuaError e => Name -> LuaE e ()
- settable :: LuaError e => StackIndex -> LuaE e ()
- setfield :: LuaError e => StackIndex -> Name -> LuaE e ()
- rawset :: LuaError e => StackIndex -> LuaE e ()
- rawseti :: LuaError e => StackIndex -> Integer -> LuaE e ()
- setmetatable :: StackIndex -> LuaE e ()
- setiuservalue :: StackIndex -> Int -> LuaE e Bool
- call :: LuaError e => NumArgs -> NumResults -> LuaE e ()
- pcall :: NumArgs -> NumResults -> Maybe StackIndex -> LuaE e Status
- load :: Reader -> Ptr () -> Name -> LuaE e Status
- loadbuffer :: ByteString -> Name -> LuaE e Status
- loadfile :: Maybe FilePath -> LuaE e Status
- loadstring :: ByteString -> LuaE e Status
- data Status
  - = OK
  - | Yield
  - | ErrRun
  - | ErrSyntax
  - | ErrMem
  - | ErrErr
  - | ErrFile
- status :: LuaE e Status
- data GCControl
  - = GCStop
  - | GCRestart
  - | GCCollect
  - | GCCount
  - | GCCountb
  - | GCStep CInt
  - | GCInc CInt CInt CInt
  - | GCGen CInt CInt
  - | GCIsRunning
- gc :: GCControl -> LuaE e Int
- next :: LuaError e => StackIndex -> LuaE e Bool
- error :: LuaE e NumResults
- concat :: LuaError e => NumArgs -> LuaE e ()
- pushglobaltable :: LuaE e ()
- register :: LuaError e => Name -> CFunction -> LuaE e ()
- setwarnf :: WarnFunction -> Ptr () -> LuaE e ()
- openbase :: LuaError e => LuaE e ()
- opendebug :: LuaError e => LuaE e ()
- openio :: LuaError e => LuaE e ()
- openlibs :: LuaE e ()
- openmath :: LuaError e => LuaE e ()
- openpackage :: LuaError e => LuaE e ()
- openos :: LuaError e => LuaE e ()
- openstring :: LuaError e => LuaE e ()
- opentable :: LuaError e => LuaE e ()
- checkstack' :: LuaError e => Int -> String -> LuaE e ()
- dostring :: ByteString -> LuaE e Status
- dofile :: Maybe FilePath -> LuaE e Status
- getmetafield :: StackIndex -> Name -> LuaE e Type
- getmetatable' :: Name -> LuaE e Type
- getsubtable :: LuaError e => StackIndex -> Name -> LuaE e Bool
- newmetatable :: Name -> LuaE e Bool
- requiref :: LuaError e => Name -> CFunction -> Bool -> LuaE e ()
- tostring' :: LuaError e => StackIndex -> LuaE e ByteString
- traceback :: State -> Maybe ByteString -> Int -> LuaE e ()
- where' :: Int -> LuaE e ()
- data Reference
  - = Reference CInt
  - | RefNil
- ref :: StackIndex -> LuaE e Reference
- getref :: LuaError e => StackIndex -> Reference -> LuaE e Type
- unref :: StackIndex -> Reference -> LuaE e ()
- fromReference :: Reference -> CInt
- toReference :: CInt -> Reference
- noref :: Int
- refnil :: Int
- loaded :: Name
- preload :: Name
- pcallTrace :: NumArgs -> NumResults -> LuaE e Status
- callTrace :: LuaError e => NumArgs -> NumResults -> LuaE e ()
- dofileTrace :: Maybe FilePath -> LuaE e Status
- dostringTrace :: ByteString -> LuaE e Status
- setwarnf' :: LuaError e => (ByteString -> LuaE e ()) -> LuaE e ()
- getupvalue :: StackIndex -> Int -> LuaE e (Maybe Name)
- setupvalue :: StackIndex -> Int -> LuaE e (Maybe Name)
- newhsuserdatauv :: a -> Int -> LuaE e ()
- newudmetatable :: Name -> LuaE e Bool
- fromuserdata :: forall a e. StackIndex -> Name -> LuaE e (Maybe a)
- putuserdata :: StackIndex -> Name -> a -> LuaE e Bool
- type HaskellFunction e = LuaE e NumResults
- pushHaskellFunction :: LuaError e => HaskellFunction e -> LuaE e ()
- pushPreCFunction :: PreCFunction -> LuaE e ()
- class Exception e => LuaError e where
  - popException :: LuaE e e
  - pushException :: e -> LuaE e ()
  - luaException :: String -> e
- newtype Exception = Exception {
  - exceptionMessage :: String
  }
- try :: Exception e => LuaE e a -> LuaE e (Either e a)
- failLua :: LuaError e => String -> LuaE e a
- throwErrorAsException :: LuaError e => LuaE e a
- throwTypeMismatchError :: LuaError e => ByteString -> StackIndex -> LuaE e a
- changeErrorType :: forall old new a. LuaE old a -> LuaE new a
- popErrorMessage :: State -> IO ByteString
- pushTypeMismatchError :: ByteString -> StackIndex -> LuaE e ()
- requirehs :: LuaError e => Name -> (Name -> LuaE e ()) -> LuaE e ()
- preloadhs :: LuaError e => Name -> LuaE e NumResults -> LuaE e ()

# Run Lua computations

run :: LuaE e a -> IO a #

Run Lua computation using the default HsLua state as starting point. Exceptions are masked, thus avoiding some issues when using multiple threads. All exceptions are passed through; error handling is the responsibility of the caller.

runWith :: State -> LuaE e a -> IO a #

Run Lua computation with the given Lua state. Exception handling is left to the caller; resulting exceptions are left unhandled.

runEither :: Exception e => LuaE e a -> IO (Either e a) #

Run the given Lua computation; exceptions raised in Haskell code are caught, but other exceptions (user exceptions raised in Haskell, unchecked type errors, etc.) are passed through.

data GCManagedState #

Wrapper of a Lua state whose lifetime is managed by the Haskell garbage collector and has a finalizer attached. This means that the state does not have to be closed explicitly, but will be closed automatically when the value is garbage collected in Haskell.

newGCManagedState :: IO GCManagedState #

Creates a new Lua state that is under the control of the Haskell garbage collector.

closeGCManagedState :: GCManagedState -> IO () #

Closes the Lua state and runs all finalizers associated with it. The state _may not_ be used after it has been closed.

withGCManagedState :: GCManagedState -> LuaE e a -> IO a #

Runs a Lua action with a state that's managed by GC.

# Lua Computations

newtype LuaE e a #

A Lua computation. This is the base type used to run Lua programs of any kind. The Lua state is handled automatically, but can be retrieved via ``state``.

Constructors

Lua |
Fields unLua :: ReaderT LuaEnvironment IO a

#### Instances

Instances details

MonadReader LuaEnvironment (LuaE e) # |
Instance details Defined in HsLua.Core.Types Methods ask :: LuaE e LuaEnvironment # local :: (LuaEnvironment -> LuaEnvironment) -> LuaE e a -> LuaE e a # reader :: (LuaEnvironment -> a) -> LuaE e a #
MonadIO (LuaE e) # |
Instance details Defined in HsLua.Core.Types Methods liftIO :: IO a -> LuaE e a #
MonadCatch (LuaE e) # |
Instance details Defined in HsLua.Core.Types Methods catch :: (HasCallStack, Exception e0) => LuaE e a -> (e0 -> LuaE e a) -> LuaE e a #
MonadMask (LuaE e) # |
Instance details Defined in HsLua.Core.Types Methods mask :: HasCallStack => ((forall a. LuaE e a -> LuaE e a) -> LuaE e b) -> LuaE e b # uninterruptibleMask :: HasCallStack => ((forall a. LuaE e a -> LuaE e a) -> LuaE e b) -> LuaE e b # generalBracket :: HasCallStack => LuaE e a -> (a -> ExitCase b -> LuaE e c) -> (a -> LuaE e b) -> LuaE e (b, c) #
MonadThrow (LuaE e) # |
Instance details Defined in HsLua.Core.Types Methods throwM :: (HasCallStack, Exception e0) => e0 -> LuaE e a #
LuaError e => Alternative (LuaE e) # |
Instance details Defined in HsLua.Core.Error Methods empty :: LuaE e a # (<|>) :: LuaE e a -> LuaE e a -> LuaE e a # some :: LuaE e a -> LuaE e [a] # many :: LuaE e a -> LuaE e [a] #
Applicative (LuaE e) # |
Instance details Defined in HsLua.Core.Types Methods pure :: a -> LuaE e a # (<*>) :: LuaE e (a -> b) -> LuaE e a -> LuaE e b # liftA2 :: (a -> b -> c) -> LuaE e a -> LuaE e b -> LuaE e c # (*>) :: LuaE e a -> LuaE e b -> LuaE e b # (<*) :: LuaE e a -> LuaE e b -> LuaE e a #
Functor (LuaE e) # |
Instance details Defined in HsLua.Core.Types Methods fmap :: (a -> b) -> LuaE e a -> LuaE e b # (<$) :: a -> LuaE e b -> LuaE e a #
Monad (LuaE e) # |
Instance details Defined in HsLua.Core.Types Methods (>>=) :: LuaE e a -> (a -> LuaE e b) -> LuaE e b # (>>) :: LuaE e a -> LuaE e b -> LuaE e b # return :: a -> LuaE e a #
LuaError e => MonadFail (LuaE e) # |
Instance details Defined in HsLua.Core.Error Methods fail :: String -> LuaE e a #

type Lua a = LuaE Exception a #

A Lua operation.

This type is suitable for most users. It uses a default exception for error handling. Users who need more control over error handling can use `LuaE` with a custom error type instead.

unsafeRunWith :: State -> LuaE e a -> IO a #

Run the given operation, but crash if any Haskell exceptions occur.

This function is identical to `runWith`; it exists for backwards compatibility.

liftIO :: MonadIO m => IO a -> m a #

Lift a computation from the `IO` monad. This allows us to run IO computations in any monadic stack, so long as it supports these kinds of operations (i.e. `IO` is the base monad for the stack).

### Example

Expand

    import Control.Monad.Trans.State -- from the "transformers" library

    printState :: Show s => StateT s IO ()
    printState = do
      state <- get
      liftIO $ print state

Had we omitted ``liftIO``, we would have ended up with this error:

    • Couldn't match type ‘IO’ with ‘StateT s IO’
     Expected type: StateT s IO ()
       Actual type: IO ()

The important part here is the mismatch between `StateT s IO ()` and ``IO` ()`.

Luckily, we know of a function that takes an ``IO` a` and returns an `(m a)`: ``liftIO``, enabling us to run the program and see the expected results:

    > evalStateT printState "hello"
    "hello"

    > evalStateT printState 3
    3

state :: LuaE e State #

Get the Lua state of this Lua computation.

newtype LuaEnvironment #

Environment in which Lua computations are evaluated.

Constructors

LuaEnvironment |
Fields luaEnvState :: State Lua interpreter state

#### Instances

Instances details

MonadReader LuaEnvironment (LuaE e) # |
Instance details Defined in HsLua.Core.Types Methods ask :: LuaE e LuaEnvironment # local :: (LuaEnvironment -> LuaEnvironment) -> LuaE e a -> LuaE e a # reader :: (LuaEnvironment -> a) -> LuaE e a #

# Lua API types

type CFunction = FunPtr PreCFunction #

Type for C functions.

In order to communicate properly with Lua, a C function must use the following protocol, which defines the way parameters and results are passed: a C function receives its arguments from Lua in its stack in direct order (the first argument is pushed first). So, when the function starts, ``lua_gettop`` returns the number of arguments received by the function. The first argument (if any) is at index 1 and its last argument is at index ``lua_gettop``. To return values to Lua, a C function just pushes them onto the stack, in direct order (the first result is pushed first), and returns the number of results. Any other value in the stack below the results will be properly discarded by Lua. Like a Lua function, a C function called by Lua can also return many results.

See lua_CFunction.

type PreCFunction = State -> IO NumResults #

Type of Haskell functions that can be turned into C functions.

This is the same as a dereferenced `CFunction`.

newtype Integer #

The type of integers in Lua.

By default this type is ``Int64``, but that can be changed to different values in Lua. (See `LUA_INT_TYPE` in `luaconf.h`.)

See lua_Integer.

Constructors

Integer Int64 |

#### Instances

Instances details

Bounded Integer |
Instance details Defined in Lua.Types Methods minBound :: Integer # maxBound :: Integer #
Enum Integer |
Instance details Defined in Lua.Types Methods succ :: Integer -> Integer # pred :: Integer -> Integer # toEnum :: Int -> Integer # fromEnum :: Integer -> Int # enumFrom :: Integer -> [Integer] # enumFromThen :: Integer -> Integer -> [Integer] # enumFromTo :: Integer -> Integer -> [Integer] # enumFromThenTo :: Integer -> Integer -> Integer -> [Integer] #
Num Integer |
Instance details Defined in Lua.Types Methods (+) :: Integer -> Integer -> Integer # (-) :: Integer -> Integer -> Integer # (*) :: Integer -> Integer -> Integer # negate :: Integer -> Integer # abs :: Integer -> Integer # signum :: Integer -> Integer # fromInteger :: Integer -> Integer #
Read Integer |
Instance details Defined in Lua.Types Methods readsPrec :: Int -> ReadS Integer # readList :: ReadS [Integer] # readPrec :: ReadPrec Integer # readListPrec :: ReadPrec [Integer] #
Integral Integer |
Instance details Defined in Lua.Types Methods quot :: Integer -> Integer -> Integer # rem :: Integer -> Integer -> Integer # div :: Integer -> Integer -> Integer # mod :: Integer -> Integer -> Integer # quotRem :: Integer -> Integer -> (Integer, Integer) # divMod :: Integer -> Integer -> (Integer, Integer) # toInteger :: Integer -> Integer #
Real Integer |
Instance details Defined in Lua.Types Methods toRational :: Integer -> Rational #
Show Integer |
Instance details Defined in Lua.Types Methods showsPrec :: Int -> Integer -> ShowS # show :: Integer -> String # showList :: [Integer] -> ShowS #
Eq Integer |
Instance details Defined in Lua.Types Methods (==) :: Integer -> Integer -> Bool # (/=) :: Integer -> Integer -> Bool #
Ord Integer |
Instance details Defined in Lua.Types Methods compare :: Integer -> Integer -> Ordering # (<) :: Integer -> Integer -> Bool # (<=) :: Integer -> Integer -> Bool # (>) :: Integer -> Integer -> Bool # (>=) :: Integer -> Integer -> Bool # max :: Integer -> Integer -> Integer # min :: Integer -> Integer -> Integer #

newtype Number #

The type of floats in Lua.

By default this type is ``Double``, but that can be changed in Lua to a single float or a long double. (See `LUA_FLOAT_TYPE` in `luaconf.h`.)

See lua_Number.

Constructors

Number Double |

#### Instances

Instances details

Floating Number |
Instance details Defined in Lua.Types Methods pi :: Number # exp :: Number -> Number # log :: Number -> Number # sqrt :: Number -> Number # (**) :: Number -> Number -> Number # logBase :: Number -> Number -> Number # sin :: Number -> Number # cos :: Number -> Number # tan :: Number -> Number # asin :: Number -> Number # acos :: Number -> Number # atan :: Number -> Number # sinh :: Number -> Number # cosh :: Number -> Number # tanh :: Number -> Number # asinh :: Number -> Number # acosh :: Number -> Number # atanh :: Number -> Number # log1p :: Number -> Number # expm1 :: Number -> Number # log1pexp :: Number -> Number # log1mexp :: Number -> Number #
RealFloat Number |
Instance details Defined in Lua.Types Methods floatRadix :: Number -> Integer # floatDigits :: Number -> Int # floatRange :: Number -> (Int, Int) # decodeFloat :: Number -> (Integer, Int) # encodeFloat :: Integer -> Int -> Number # exponent :: Number -> Int # significand :: Number -> Number # scaleFloat :: Int -> Number -> Number # isNaN :: Number -> Bool # isInfinite :: Number -> Bool # isDenormalized :: Number -> Bool # isNegativeZero :: Number -> Bool # isIEEE :: Number -> Bool # atan2 :: Number -> Number -> Number #
Num Number |
Instance details Defined in Lua.Types Methods (+) :: Number -> Number -> Number # (-) :: Number -> Number -> Number # (*) :: Number -> Number -> Number # negate :: Number -> Number # abs :: Number -> Number # signum :: Number -> Number # fromInteger :: Integer -> Number #
Read Number |
Instance details Defined in Lua.Types Methods readsPrec :: Int -> ReadS Number # readList :: ReadS [Number] # readPrec :: ReadPrec Number # readListPrec :: ReadPrec [Number] #
Fractional Number |
Instance details Defined in Lua.Types Methods (/) :: Number -> Number -> Number # recip :: Number -> Number # fromRational :: Rational -> Number #
Real Number |
Instance details Defined in Lua.Types Methods toRational :: Number -> Rational #
RealFrac Number |
Instance details Defined in Lua.Types Methods properFraction :: Integral b => Number -> (b, Number) # truncate :: Integral b => Number -> b # round :: Integral b => Number -> b # ceiling :: Integral b => Number -> b # floor :: Integral b => Number -> b #
Show Number |
Instance details Defined in Lua.Types Methods showsPrec :: Int -> Number -> ShowS # show :: Number -> String # showList :: [Number] -> ShowS #
Eq Number |
Instance details Defined in Lua.Types Methods (==) :: Number -> Number -> Bool # (/=) :: Number -> Number -> Bool #
Ord Number |
Instance details Defined in Lua.Types Methods compare :: Number -> Number -> Ordering # (<) :: Number -> Number -> Bool # (<=) :: Number -> Number -> Bool # (>) :: Number -> Number -> Bool # (>=) :: Number -> Number -> Bool # max :: Number -> Number -> Number # min :: Number -> Number -> Number #

## Stack index

newtype StackIndex #

A stack index

Constructors

StackIndex |
Fields fromStackIndex :: CInt

#### Instances

Instances details

Enum StackIndex |
Instance details Defined in Lua.Types Methods succ :: StackIndex -> StackIndex # pred :: StackIndex -> StackIndex # toEnum :: Int -> StackIndex # fromEnum :: StackIndex -> Int # enumFrom :: StackIndex -> [StackIndex] # enumFromThen :: StackIndex -> StackIndex -> [StackIndex] # enumFromTo :: StackIndex -> StackIndex -> [StackIndex] # enumFromThenTo :: StackIndex -> StackIndex -> StackIndex -> [StackIndex] #
Num StackIndex |
Instance details Defined in Lua.Types Methods (+) :: StackIndex -> StackIndex -> StackIndex # (-) :: StackIndex -> StackIndex -> StackIndex # (*) :: StackIndex -> StackIndex -> StackIndex # negate :: StackIndex -> StackIndex # abs :: StackIndex -> StackIndex # signum :: StackIndex -> StackIndex # fromInteger :: Integer -> StackIndex #
Show StackIndex |
Instance details Defined in Lua.Types Methods showsPrec :: Int -> StackIndex -> ShowS # show :: StackIndex -> String # showList :: [StackIndex] -> ShowS #
Eq StackIndex |
Instance details Defined in Lua.Types Methods (==) :: StackIndex -> StackIndex -> Bool # (/=) :: StackIndex -> StackIndex -> Bool #
Ord StackIndex |
Instance details Defined in Lua.Types Methods compare :: StackIndex -> StackIndex -> Ordering # (<) :: StackIndex -> StackIndex -> Bool # (<=) :: StackIndex -> StackIndex -> Bool # (>) :: StackIndex -> StackIndex -> Bool # (>=) :: StackIndex -> StackIndex -> Bool # max :: StackIndex -> StackIndex -> StackIndex # min :: StackIndex -> StackIndex -> StackIndex #

nthTop :: CInt -> StackIndex #

Stack index of the nth element from the top of the stack.

Since: lua-2.0.0

nthBottom :: CInt -> StackIndex #

Stack index of the nth element from the bottom of the stack.

Since: lua-2.0.0

nth :: CInt -> StackIndex #

Alias for `nthTop`.

Since: lua-2.0.0

top :: StackIndex #

Index of the topmost stack element.

Since: lua-2.0.0

## Number of arguments and return values

newtype NumArgs #

The number of arguments consumed curing a function call.

Constructors

NumArgs |
Fields fromNumArgs :: CInt

#### Instances

Instances details

Num NumArgs |
Instance details Defined in Lua.Types Methods (+) :: NumArgs -> NumArgs -> NumArgs # (-) :: NumArgs -> NumArgs -> NumArgs # (*) :: NumArgs -> NumArgs -> NumArgs # negate :: NumArgs -> NumArgs # abs :: NumArgs -> NumArgs # signum :: NumArgs -> NumArgs # fromInteger :: Integer -> NumArgs #
Show NumArgs |
Instance details Defined in Lua.Types Methods showsPrec :: Int -> NumArgs -> ShowS # show :: NumArgs -> String # showList :: [NumArgs] -> ShowS #
Eq NumArgs |
Instance details Defined in Lua.Types Methods (==) :: NumArgs -> NumArgs -> Bool # (/=) :: NumArgs -> NumArgs -> Bool #
Ord NumArgs |
Instance details Defined in Lua.Types Methods compare :: NumArgs -> NumArgs -> Ordering # (<) :: NumArgs -> NumArgs -> Bool # (<=) :: NumArgs -> NumArgs -> Bool # (>) :: NumArgs -> NumArgs -> Bool # (>=) :: NumArgs -> NumArgs -> Bool # max :: NumArgs -> NumArgs -> NumArgs # min :: NumArgs -> NumArgs -> NumArgs #

newtype NumResults #

The number of results returned by a function call.

Constructors

NumResults |
Fields fromNumResults :: CInt

#### Instances

Instances details

Num NumResults |
Instance details Defined in Lua.Types Methods (+) :: NumResults -> NumResults -> NumResults # (-) :: NumResults -> NumResults -> NumResults # (*) :: NumResults -> NumResults -> NumResults # negate :: NumResults -> NumResults # abs :: NumResults -> NumResults # signum :: NumResults -> NumResults # fromInteger :: Integer -> NumResults #
Show NumResults |
Instance details Defined in Lua.Types Methods showsPrec :: Int -> NumResults -> ShowS # show :: NumResults -> String # showList :: [NumResults] -> ShowS #
Eq NumResults |
Instance details Defined in Lua.Types Methods (==) :: NumResults -> NumResults -> Bool # (/=) :: NumResults -> NumResults -> Bool #
Ord NumResults |
Instance details Defined in Lua.Types Methods compare :: NumResults -> NumResults -> Ordering # (<) :: NumResults -> NumResults -> Bool # (<=) :: NumResults -> NumResults -> Bool # (>) :: NumResults -> NumResults -> Bool # (>=) :: NumResults -> NumResults -> Bool # max :: NumResults -> NumResults -> NumResults # min :: NumResults -> NumResults -> NumResults #

## Table fields

newtype Name #

Name of a function, table field, or chunk; the name must be valid UTF-8 and may not contain any nul characters.

Implementation note: this is a `newtype` instead of a simple `type Name = ByteString` alias so we can define a UTF-8 based `IsString` instance. Non-ASCII users would have a bad time otherwise.

Constructors

Name |
Fields fromName :: ByteString

#### Instances

Instances details

Semigroup Name # |
Instance details Defined in HsLua.Core.Types Methods (<>) :: Name -> Name -> Name # sconcat :: NonEmpty Name -> Name # stimes :: Integral b => b -> Name -> Name #
IsString Name # |
Instance details Defined in HsLua.Core.Types Methods fromString :: String -> Name #
Show Name # |
Instance details Defined in HsLua.Core.Types Methods showsPrec :: Int -> Name -> ShowS # show :: Name -> String # showList :: [Name] -> ShowS #
Eq Name # |
Instance details Defined in HsLua.Core.Types Methods (==) :: Name -> Name -> Bool # (/=) :: Name -> Name -> Bool #
Ord Name # |
Instance details Defined in HsLua.Core.Types Methods compare :: Name -> Name -> Ordering # (<) :: Name -> Name -> Bool # (<=) :: Name -> Name -> Bool # (>) :: Name -> Name -> Bool # (>=) :: Name -> Name -> Bool # max :: Name -> Name -> Name # min :: Name -> Name -> Name #

# Lua API

## Constants and pseudo-indices

multret :: NumResults #

Option for multiple returns in ``pcall``.

registryindex :: StackIndex #

Pseudo stack index of the Lua registry.

upvalueindex :: StackIndex -> StackIndex #

Returns the pseudo-index that represents the `i`-th upvalue of the running function (see <https://www.lua.org/manual/5.4/manual.html#4.2 §4.2> of the Lua 5.4 reference manual).

See also: lua_upvalueindex.

## State manipulation

newtype State #

An opaque structure that points to a thread and indirectly (through the thread) to the whole state of a Lua interpreter. The Lua library is fully reentrant: it has no global variables. All information about a state is accessible through this structure.

Synonym for `lua_State *`. See lua_State.

Constructors

State (Ptr ()) |

#### Instances

Instances details

Generic State |
Instance details Defined in Lua.Types Associated Types
type Rep State |
Instance details Defined in Lua.Types type Rep State = D1 ('MetaData "State" "Lua.Types" "lua-2.3.3-4jWjPpu4zMu97sTfBSZCE4" 'True) (C1 ('MetaCons "State" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Ptr ()))))
Methods from :: State -> Rep State x # to :: Rep State x -> State #
Eq State |
Instance details Defined in Lua.Types Methods (==) :: State -> State -> Bool # (/=) :: State -> State -> Bool #
type Rep State |
Instance details Defined in Lua.Types type Rep State = D1 ('MetaData "State" "Lua.Types" "lua-2.3.3-4jWjPpu4zMu97sTfBSZCE4" 'True) (C1 ('MetaCons "State" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Ptr ()))))

newstate :: IO State #

Creates a new Lua state. It calls `lua_newstate` with an allocator based on the standard C `realloc` function and then sets a panic function (see §4.4 of the Lua 5.4 Reference Manual) that prints an error message to the standard error output in case of fatal errors.

Wraps `hsluaL_newstate`. See also: luaL_newstate.

close :: State -> IO () #

Destroys all objects in the given Lua state (calling the corresponding garbage-collection metamethods, if any) and frees all dynamic memory used by this state. On several platforms, you may not need to call this function, because all resources are naturally released when the host program ends. On the other hand, long-running programs that create multiple states, such as daemons or web servers, will probably need to close states as soon as they are not needed.

Same as `lua_close`.

## Basic stack manipulation

absindex :: StackIndex -> LuaE e StackIndex #

Converts the acceptable index `idx` into an equivalent absolute index (that is, one that does not depend on the stack top).

Wraps `lua_absindex`.

gettop :: LuaE e StackIndex #

Returns the index of the top element in the stack. Because indices start at 1, this result is equal to the number of elements in the stack (and so 0 means an empty stack).

Wraps `lua_gettop`.

settop :: StackIndex -> LuaE e () #

Accepts any index, or 0, and sets the stack top to this index. If the new top is larger than the old one, then the new elements are filled with nil. If index is 0, then all stack elements are removed.

Wraps `lua_settop`.

pushvalue :: StackIndex -> LuaE e () #

Pushes a copy of the element at the given index onto the stack.

Wraps `lua_pushvalue`.

copy :: StackIndex -> StackIndex -> LuaE e () #

Copies the element at index `fromidx` into the valid index `toidx`, replacing the value at that position. Values at other positions are not affected.

Wraps `lua_copy`.

insert :: StackIndex -> LuaE e () #

Moves the top element into the given valid index, shifting up the elements above this index to open space. This function cannot be called with a pseudo-index, because a pseudo-index is not an actual stack position.

Wraps `lua_insert`.

rotate #

Arguments

:: StackIndex |
    idx
-> Int |
    n
-> LuaE e () |

Rotates the stack elements between the valid index `idx` and the top of the stack. The elements are rotated `n` positions in the direction of the top, for a positive `n`, or `-n` positions in the direction of the bottom, for a negative `n`. The absolute value of `n` must not be greater than the size of the slice being rotated. This function cannot be called with a pseudo-index, because a pseudo-index is not an actual stack position.

https://www.lua.org/manual/5.4/manual.html#lua_rotate

pop :: Int -> LuaE e () #

Pops `n` elements from the stack.

See also: lua_pop.

remove :: StackIndex -> LuaE e () #

Removes the element at the given valid index, shifting down the elements above this index to fill the gap. This function cannot be called with a pseudo-index, because a pseudo-index is not an actual stack position.

Wraps `lua_remove`.

replace :: StackIndex -> LuaE e () #

Moves the top element into the given valid index without shifting any element (therefore replacing the value at that given index), and then pops the top element.

Wraps `lua_replace`.

checkstack :: Int -> LuaE e Bool #

Ensures that the stack has space for at least `n` extra slots (that is, that you can safely push up to `n` values into it). It returns false if it cannot fulfill the request, either because it would cause the stack to be larger than a fixed maximum size (typically at least several thousand elements) or because it cannot allocate memory for the extra space. This function never shrinks the stack; if the stack already has space for the extra slots, it is left unchanged.

Wraps `lua_checkstack`.

## types and type checks

data Type #

Enumeration used as type tag. See lua_type.

Constructors

TypeNone | non-valid stack index
TypeNil | type of Lua's `nil` value
TypeBoolean | type of Lua booleans
TypeLightUserdata | type of light userdata
TypeNumber | type of Lua numbers. See ``Number``
TypeString | type of Lua string values
TypeTable | type of Lua tables
TypeFunction | type of functions, either normal or ``CFunction``
TypeUserdata | type of full user data
TypeThread | type of Lua threads

#### Instances

Instances details

Bounded Type # |
Instance details Defined in HsLua.Core.Types Methods minBound :: Type # maxBound :: Type #
Enum Type # |
Instance details Defined in HsLua.Core.Types Methods succ :: Type -> Type # pred :: Type -> Type # toEnum :: Int -> Type # fromEnum :: Type -> Int # enumFrom :: Type -> [Type] # enumFromThen :: Type -> Type -> [Type] # enumFromTo :: Type -> Type -> [Type] # enumFromThenTo :: Type -> Type -> Type -> [Type] #
Read Type # |
Instance details Defined in HsLua.Core.Types Methods readsPrec :: Int -> ReadS Type # readList :: ReadS [Type] # readPrec :: ReadPrec Type # readListPrec :: ReadPrec [Type] #
Show Type # |
Instance details Defined in HsLua.Core.Types Methods showsPrec :: Int -> Type -> ShowS # show :: Type -> String # showList :: [Type] -> ShowS #
Eq Type # |
Instance details Defined in HsLua.Core.Types Methods (==) :: Type -> Type -> Bool # (/=) :: Type -> Type -> Bool #
Ord Type # |
Instance details Defined in HsLua.Core.Types Methods compare :: Type -> Type -> Ordering # (<) :: Type -> Type -> Bool # (<=) :: Type -> Type -> Bool # (>) :: Type -> Type -> Bool # (>=) :: Type -> Type -> Bool # max :: Type -> Type -> Type # min :: Type -> Type -> Type #

ltype :: StackIndex -> LuaE e Type #

Returns the type of the value in the given valid index, or ``TypeNone`` for a non-valid (but acceptable) index.

This function wraps `lua_type`.

typename :: Type -> LuaE e ByteString #

Returns the name of the type encoded by the value `tp`, which must be one the values returned by ``ltype``.

Wraps `lua_typename`.

isboolean :: StackIndex -> LuaE e Bool #

Returns `True` if the value at the given index is a boolean, and `False` otherwise.

Wraps `lua_isboolean`.

iscfunction :: StackIndex -> LuaE e Bool #

Returns `True` if the value at the given index is a C function, and `False` otherwise.

Wraps `lua_iscfunction`.

isfunction :: StackIndex -> LuaE e Bool #

Returns `True` if the value at the given index is a function (either C or Lua), and `False` otherwise.

Wraps `lua_isfunction`.

isinteger :: StackIndex -> LuaE e Bool #

Returns `True` if the value at the given index is an integer (that is, the value is a number and is represented as an integer), and `False` otherwise.

Wraps `lua_isinteger`.

islightuserdata :: StackIndex -> LuaE e Bool #

Returns `True` if the value at the given index is a light userdata, and `False` otherwise.

Wraps `lua_islightuserdata`.

isnil :: StackIndex -> LuaE e Bool #

Returns `True` if the value at the given index is *nil*, and `False` otherwise.

Wraps `lua_isnil`.

isnone :: StackIndex -> LuaE e Bool #

Returns `True` if the given index is not valid, and `False` otherwise.

Wraps `lua_isnone`.

isnoneornil :: StackIndex -> LuaE e Bool #

Returns `True` if the given index is not valid or if the value at the given index is *nil*, and `False` otherwise.

Wraps `lua_isnoneornil`.

isnumber :: StackIndex -> LuaE e Bool #

Returns `True` if the value at the given index is a number or a string convertible to a number, and `False` otherwise.

Wraps `lua_isnumber`.

isstring :: StackIndex -> LuaE e Bool #

Returns `True` if the value at the given index is a string or a number (which is always convertible to a string), and `False` otherwise.

Wraps `lua_isstring`.

istable :: StackIndex -> LuaE e Bool #

Returns `True` if the value at the given index is a table, and `False` otherwise.

Wraps `lua_istable`.

isthread :: StackIndex -> LuaE e Bool #

Returns `True` if the value at the given index is a thread, and `False` otherwise.

Wraps `lua_isthread`.

isuserdata :: StackIndex -> LuaE e Bool #

Returns `True` if the value at the given index is a userdata (either full or light), and `False` otherwise.

Wraps `lua_isuserdata`.

## access functions (stack → Haskell)

toboolean :: StackIndex -> LuaE e Bool #

Converts the Lua value at the given index to a haskell boolean value. Like all tests in Lua, `toboolean` returns `True` for any Lua value different from `false` and `nil`; otherwise it returns `False`. (If you want to accept only actual boolean values, use ``isboolean`` to test the value's type.)

Wraps `lua_toboolean`.

tocfunction :: StackIndex -> LuaE e (Maybe CFunction) #

Converts a value at the given index to a C function. That value must be a C function; otherwise, returns `Nothing`.

Wraps `lua_tocfunction`.

tointeger :: StackIndex -> LuaE e (Maybe Integer) #

Converts the Lua value at the given acceptable index to the signed integral type `Integer`. The Lua value must be an integer, a number or a string convertible to an integer (see §3.4.3 of the Lua 5.4 Reference Manual); otherwise, `tointeger` returns `Nothing`.

If the number is not an integer, it is truncated in some non-specified way.

Wraps `lua_tointegerx`. See also: lua_tointeger.

tonumber :: StackIndex -> LuaE e (Maybe Number) #

Converts the Lua value at the given index to a `Number`. The Lua value must be a number or a string convertible to a number; otherwise, `tonumber` returns ``Nothing``.

Wraps `lua_tonumberx`. See also lua_tonumber.

topointer :: StackIndex -> LuaE e (Ptr ()) #

Converts the value at the given index to a generic C pointer (void*). The value can be a userdata, a table, a thread, or a function; otherwise, lua_topointer returns `nullPtr`. Different objects will give different pointers. There is no way to convert the pointer back to its original value.

Typically this function is used only for hashing and debug information.

Wraps `lua_topointer`.

tostring :: StackIndex -> LuaE e (Maybe ByteString) #

Converts the Lua value at the given index to a `ByteString`. The Lua value must be a string or a number; otherwise, the function returns `Nothing`. If the value is a number, then `tostring` also changes the actual value in the stack to a string. (This change confuses `next` when `tostring` is applied to keys during a table traversal.)

Wraps `lua_tolstring`.

tothread :: StackIndex -> LuaE e (Maybe State) #

Converts the value at the given index to a Lua thread (represented as `State`). This value must be a thread; otherwise, the function returns `Nothing`.

Wraps `lua_tothread`.

touserdata :: StackIndex -> LuaE e (Maybe (Ptr a)) #

If the value at the given index is a full userdata, returns its block address. If the value is a light userdata, returns its pointer. Otherwise, returns `Nothing`..

Wraps `lua_touserdata`.

rawlen :: StackIndex -> LuaE e Int #

Returns the raw "length" of the value at the given index: for strings, this is the string length; for tables, this is the result of the length operator (`#`) with no metamethods; for userdata, this is the size of the block of memory allocated for the userdata; for other values, it is 0.

Wraps `lua_rawlen`.

## Comparison and arithmetic functions

data RelationalOperator #

Lua comparison operations.

Constructors

EQ | Correponds to Lua's equality (==) operator.
LT | Correponds to Lua's strictly-lesser-than (<) operator
LE | Correponds to Lua's lesser-or-equal (<=) operator

#### Instances

Instances details

Show RelationalOperator # |
Instance details Defined in HsLua.Core.Types Methods showsPrec :: Int -> RelationalOperator -> ShowS # show :: RelationalOperator -> String # showList :: [RelationalOperator] -> ShowS #
Eq RelationalOperator # |
Instance details Defined in HsLua.Core.Types Methods (==) :: RelationalOperator -> RelationalOperator -> Bool # (/=) :: RelationalOperator -> RelationalOperator -> Bool #
Ord RelationalOperator # |
Instance details Defined in HsLua.Core.Types Methods compare :: RelationalOperator -> RelationalOperator -> Ordering # (<) :: RelationalOperator -> RelationalOperator -> Bool # (<=) :: RelationalOperator -> RelationalOperator -> Bool # (>) :: RelationalOperator -> RelationalOperator -> Bool # (>=) :: RelationalOperator -> RelationalOperator -> Bool # max :: RelationalOperator -> RelationalOperator -> RelationalOperator # min :: RelationalOperator -> RelationalOperator -> RelationalOperator #

compare #

Arguments

:: LuaError e |
=> StackIndex | idx1
-> StackIndex | idx2
-> RelationalOperator |
-> LuaE e Bool |

Compares two Lua values. Returns `True` if the value at index `idx1` satisfies `op` when compared with the value at index `idx2`, following the semantics of the corresponding Lua operator (that is, it may call metamethods). Otherwise returns `False`. Also returns `False` if any of the indices is not valid.

The value of op must be of type `RelationalOperator`:

EQ: compares for equality (==) LT: compares for less than (<) LE: compares for less or equal (<=)

Wraps `hslua_compare`. See also lua_compare.

equal #

Arguments

:: LuaError e |
=> StackIndex | index1
-> StackIndex | index2
-> LuaE e Bool |

Returns `True` if the two values in acceptable indices `index1` and `index2` are equal, following the semantics of the Lua `==` operator (that is, may call metamethods). Otherwise returns `False`. Also returns `False` if any of the indices is non valid. Uses ``compare`` internally.

lessthan :: LuaError e => StackIndex -> StackIndex -> LuaE e Bool #

Tests whether the object under the first index is smaller than that under the second. Uses ``compare`` internally.

rawequal :: StackIndex -> StackIndex -> LuaE e Bool #

Returns `True` if the two values in indices `idx1` and `idx2` are primitively equal (that is, without calling the `__eq` metamethod). Otherwise returns `False`. Also returns `False` if any of the indices are not valid.

Wraps `lua_rawequal`.

## push functions (Haskell → stack)

pushboolean :: Bool -> LuaE e () #

Pushes a boolean value with the given value onto the stack.

This functions wraps `lua_pushboolean`.

pushcfunction :: CFunction -> LuaE e () #

Pushes a C function onto the stack. This function receives a pointer to a C function and pushes onto the stack a Lua value of type function that, when called, invokes the corresponding C function.

Any function to be callable by Lua must follow the correct protocol to receive its parameters and return its results (see ``CFunction``)

Same as `flip `pushcclosure` 0`. lua_pushcfunction.

pushcclosure #

Arguments

:: CFunction |
-> NumArgs | n
-> LuaE e () |

Pushes a new C closure onto the stack.

When a C function is created, it is possible to associate some values with it, thus creating a C closure (see §3.4); these values are then accessible to the function whenever it is called. To associate values with a C function, first these values should be pushed onto the stack (when there are multiple values, the first value is pushed first). Then pushcclosure is called to create and push the C function onto the stack, with the argument `n` telling how many values should be associated with the function. pushcclosure also pops these values from the stack.

The maximum value for `n` is 255.

Wraps `lua_pushcclosure`.

pushinteger :: Integer -> LuaE e () #

Pushes an integer with with the given value onto the stack.

Wraps `lua_pushinteger`.

pushlightuserdata :: Ptr a -> LuaE e () #

Pushes a light userdata onto the stack.

Userdata represent C values in Lua. A light userdata represents a pointer, a `Ptr a` (i.e., `void*` in C). It is a value (like a number): you do not create it, it has no individual metatable, and it is not collected (as it was never created). A light userdata is equal to "any" light userdata with the same C address.

Wraps `lua_pushlightuserdata`.

pushnil :: LuaE e () #

Pushes a nil value onto the stack.

Wraps `lua_pushnil`.

pushnumber :: Number -> LuaE e () #

Pushes a float with the given value onto the stack.

Wraps `lua_pushnumber`.

pushstring :: ByteString -> LuaE e () #

Pushes the string pointed to by s onto the stack. Lua makes (or reuses) an internal copy of the given string, so the memory at s can be freed or reused immediately after the function returns.

Wraps `lua_pushlstring`.

pushthread :: LuaE e Bool #

Pushes the current thread onto the stack. Returns `True` if this thread is the main thread of its state, `False` otherwise.

Wraps `lua_pushthread`.

## get functions (Lua → stack)

getglobal :: LuaError e => Name -> LuaE e Type #

Pushes onto the stack the value of the global `name`.

Errors on the Lua side are propagated.

Wraps `hslua_getglobal`.

gettable :: LuaError e => StackIndex -> LuaE e Type #

Pushes onto the stack the value `t[k]`, where `t` is the value at the given index and `k` is the value at the top of the stack.

This function pops the key from the stack, pushing the resulting value in its place. As in Lua, this function may trigger a metamethod for the "index" event (see §2.4 of Lua's manual).

Errors on the Lua side are caught and rethrown.

Wraps `hslua_gettable`. See also: lua_gettable.

getfield :: LuaError e => StackIndex -> Name -> LuaE e Type #

Pushes onto the stack the value `t[k]`, where `t` is the value at the given stack index. As in Lua, this function may trigger a metamethod for the "index" event (see §2.4 of Lua's manual).

Errors on the Lua side are propagated.

See also lua_getfield.

rawget :: LuaError e => StackIndex -> LuaE e Type #

Similar to ``gettable``, but does a raw access (i.e., without metamethods).

Wraps `lua_rawget`.

rawgeti :: LuaError e => StackIndex -> Integer -> LuaE e Type #

Pushes onto the stack the value `t[n]`, where `t` is the table at the given index. The access is raw, that is, it does not invoke the `__index` metamethod.

Wraps `lua_rawgeti`.

createtable :: Int -> Int -> LuaE e () #

Creates a new empty table and pushes it onto the stack. Parameter narr is a hint for how many elements the table will have as a sequence; parameter nrec is a hint for how many other elements the table will have. Lua may use these hints to preallocate memory for the new table. This preallocation is useful for performance when you know in advance how many elements the table will have. Otherwise you can use the function lua_newtable.

Wraps `lua_createtable`.

newtable :: LuaE e () #

Creates a new empty table and pushes it onto the stack. It is equivalent to `createtable 0 0`.

See also: lua_newtable.

newuserdatauv #

Arguments

:: Int | size
-> Int | nuvalue
-> LuaE e (Ptr ()) |

This function creates and pushes on the stack a new full userdata, with `nuvalue` associated Lua values, called `user values`, plus an associated block of raw memory with `size` bytes. (The user values can be set and read with the functions `lua_setiuservalue` and `lua_getiuservalue`.)

The function returns the address of the block of memory. Lua ensures that this address is valid as long as the corresponding userdata is alive (see §2.5). Moreover, if the userdata is marked for finalization (see §2.5.3), its address is valid at least until the call to its finalizer.

This function wraps `lua_newuserdatauv`.

getmetatable :: StackIndex -> LuaE e Bool #

If the value at the given index has a metatable, the function pushes that metatable onto the stack and returns `True`. Otherwise, the function returns `False` and pushes nothing on the stack.

Wraps `lua_getmetatable`.

getiuservalue #

Arguments

:: StackIndex | index
-> Int | n
-> LuaE e Type |

Pushes onto the stack the `n`-th user value associated with the full userdata at the given index and returns the type of the pushed value.

If the userdata does not have that value, pushes nil and returns `LUA_TNONE`.

Wraps `lua_getiuservalue`.

## set functions (stack → Lua)

setglobal #

Arguments

:: LuaError e |
=> Name | name
-> LuaE e () |

Pops a value from the stack and sets it as the new value of global `name`.

Errors on the Lua side are caught and rethrown as `Exception`.

Wraps `hslua_setglobal`. See also: lua_setglobal.

settable :: LuaError e => StackIndex -> LuaE e () #

Does the equivalent to `t[k] = v`, where `t` is the value at the given index, `v` is the value at the top of the stack, and `k` is the value just below the top.

This function pops both the key and the value from the stack. As in Lua, this function may trigger a metamethod for the "newindex" event (see §2.4 of the Lua 5.4 Reference Manual).

Errors on the Lua side are caught and rethrown.

Wraps `hslua_settable`.

setfield :: LuaError e => StackIndex -> Name -> LuaE e () #

Does the equivalent to `t[k] = v`, where `t` is the value at the given index and `v` is the value at the top of the stack.

This function pops the value from the stack. As in Lua, this function may trigger a metamethod for the "newindex" event (see §2.4 of the Lua 5.4 Reference Manual).

Errors on the Lua side are caught and rethrown as a ``Exception``.

See also: lua_setfield.

rawset :: LuaError e => StackIndex -> LuaE e () #

Similar to ``settable``, but does a raw assignment (i.e., without metamethods).

Wraps `lua_rawset`.

rawseti :: LuaError e => StackIndex -> Integer -> LuaE e () #

Does the equivalent of `t[i] = v`, where `t` is the table at the given index and `v` is the value at the top of the stack.

This function pops the value from the stack. The assignment is raw, that is, it does not invoke the `__newindex` metamethod.

Wraps `lua_rawseti`.

setmetatable :: StackIndex -> LuaE e () #

Pops a table from the stack and sets it as the new metatable for the value at the given index.

Wraps `lua_setmetatable`.

setiuservalue #

Arguments

:: StackIndex | index
-> Int | n
-> LuaE e Bool |

Pops a value from the stack and sets it as the new `n`-th user value associated to the full userdata at the given index. Returns 0 if the userdata does not have that value.

Wraps `lua_setiuservalue`.

## load and call functions (load and run Lua code)

call :: LuaError e => NumArgs -> NumResults -> LuaE e () #

Calls a function.

To call a function you must use the following protocol: first, the function to be called is pushed onto the stack; then, the arguments to the function are pushed in direct order; that is, the first argument is pushed first. Finally you call `call`; `nargs` is the number of arguments that you pushed onto the stack. All arguments and the function value are popped from the stack when the function is called. The function results are pushed onto the stack when the function returns. The number of results is adjusted to `nresults`, unless `nresults` is `multret`. In this case, all results from the function are pushed. Lua takes care that the returned values fit into the stack space. The function results are pushed onto the stack in direct order (the first result is pushed first), so that after the call the last result is on the top of the stack.

Any error inside the called function is propagated as exception of type `e`.

The following example shows how the host program can do the equivalent to this Lua code:

    a = f("how", t.x, 14)

Here it is in Haskell (assuming the OverloadedStrings language extension):

    getglobal "f"         -- function to be called
    pushstring  "how"     -- 1st argument
    getglobal "t"         -- table to be indexed
    getfield (-1) "x"     -- push result of t.x (2nd arg)
    remove (-2)           -- remove 't' from the stack
    pushinteger 14        -- 3rd argument
    call 3 1              -- call 'f' with 3 arguments and 1 result
    setglobal "a"         -- set global 'a'

Note that the code above is "balanced": at its end, the stack is back to its original configuration. This is considered good programming practice.

See lua_call.

pcall :: NumArgs -> NumResults -> Maybe StackIndex -> LuaE e Status #

Calls a function in protected mode.

Both `nargs` and `nresults` have the same meaning as in ``call``. If there are no errors during the call, `pcall` behaves exactly like ``call``. However, if there is any error, `pcall` catches it, pushes a single value on the stack (the error message), and returns the error code. Like ``call``, `pcall` always removes the function and its arguments from the stack.

If `msgh` is `Nothing`, then the error object returned on the stack is exactly the original error object. Otherwise, when `msgh` is `Just idx`, the stack index `idx` is the location of a message handler. (This index cannot be a pseudo-index.) In case of runtime errors, this function will be called with the error object and its return value will be the object returned on the stack by ``pcall``.

Typically, the message handler is used to add more debug information to the error object, such as a stack traceback. Such information cannot be gathered after the return of ``pcall``, since by then the stack has unwound.

This function wraps `lua_pcall`.

load :: Reader -> Ptr () -> Name -> LuaE e Status #

Loads a Lua chunk (without running it). If there are no errors, ``load`` pushes the compiled chunk as a Lua function on top of the stack. Otherwise, it pushes an error message.

The return values of ``load`` are:

- ``OK``: no errors;
- ``ErrSyntax``: syntax error during pre-compilation;
- ``ErrMem``: memory allocation error;
- ``ErrGcmm``: error while running a `__gc` metamethod. (This error has no relation with the chunk being loaded. It is generated by the garbage collector.)

This function only loads a chunk; it does not run it.

`load` automatically detects whether the chunk is text or binary, and loads it accordingly (see program luac).

The ``load`` function uses a user-supplied reader function to read the chunk (see ``Reader``). The data argument is an opaque value passed to the reader function.

The `chunkname` argument gives a name to the chunk, which is used for error messages and in debug information (see §4.7). Note that the `chunkname` is used as a C string, so it may not contain null-bytes.

This is a wrapper of `lua_load`.

loadbuffer #

Arguments

:: ByteString | Program to load
-> Name | chunk name
-> LuaE e Status |

Loads a ByteString as a Lua chunk.

This function returns the same results as ``load``. `name` is the chunk name, used for debug information and error messages. Note that `name` is used as a C string, so it may not contain null-bytes.

Wraps `luaL_loadbuffer`.

loadfile #

Arguments

:: Maybe FilePath | filename
-> LuaE e Status |

Loads a file as a Lua chunk. This function uses `lua_load` (see ``load``) to load the chunk in the file named `filename`. If filename is `Nothing`, then it loads from the standard input. The first line in the file is ignored if it starts with a `#`.

The string mode works as in function ``load``.

This function returns the same results as ``load``, but it has an extra error code ``ErrFile`` for file-related errors (e.g., it cannot open or read the file).

As ``load``, this function only loads the chunk; it does not run it.

See luaL_loadfile.

loadstring :: ByteString -> LuaE e Status #

Loads a string as a Lua chunk. This function uses `lua_load` to load the chunk in the given ByteString. The given string may not contain any NUL characters.

This function returns the same results as `lua_load` (see ``load``).

Also as ``load``, this function only loads the chunk; it does not run it.

See luaL_loadstring.

## Coroutine functions

data Status #

Lua status values.

Constructors

OK | success
Yield | yielding / suspended coroutine
ErrRun | a runtime rror
ErrSyntax | syntax error during precompilation
ErrMem | memory allocation (out-of-memory) error.
ErrErr | error while running the message handler.
ErrFile | opening or reading a file failed.

#### Instances

Instances details

Show Status # |
Instance details Defined in HsLua.Core.Types Methods showsPrec :: Int -> Status -> ShowS # show :: Status -> String # showList :: [Status] -> ShowS #
Eq Status # |
Instance details Defined in HsLua.Core.Types Methods (==) :: Status -> Status -> Bool # (/=) :: Status -> Status -> Bool #

status :: LuaE e Status #

Returns the status of this Lua thread.

The status can be `OK` for a normal thread, an error value if the thread finished the execution of a `lua_resume` with an error, or `Yield` if the thread is suspended.

You can only call functions in threads with status `OK`. You can resume threads with status `OK` (to start a new coroutine) or `Yield` (to resume a coroutine).

Wraps `lua_status`.

## garbage-collection function and options

data GCControl #

Commands to control the garbage collector.

Constructors

GCStop | stops the garbage collector.
GCRestart | restarts the garbage collector
GCCollect | performs a full garbage-collection cycle.
GCCount | returns the current amount of memory (in Kbytes) in use by Lua.
GCCountb | returns the remainder of dividing the current amount of bytes of memory in use by Lua by 1024.
GCStep CInt | performs an incremental step of garbage collection, corresponding to the allocation of `stepsize` Kbytes.
GCInc CInt CInt CInt | Changes the collector to incremental mode with the given parameters (see <https://www.lua.org/manual/5.4/manual.html#2.5.1 §2.5.1>). Returns the previous mode (`LUA_GCGEN` or `LUA_GCINC`). Parameters: pause, stepmul, and stepsize.
GCGen CInt CInt | Changes the collector to generational mode with the given parameters (see <https://www.lua.org/manual/5.4/manual.html#2.5.2 §2.5.2>). Returns the previous mode (`LUA_GCGEN` or `LUA_GCINC`).
GCIsRunning | returns a boolean that tells whether the collector is running (i.e., not stopped).

#### Instances

Instances details

Show GCControl # |
Instance details Defined in HsLua.Core.Types Methods showsPrec :: Int -> GCControl -> ShowS # show :: GCControl -> String # showList :: [GCControl] -> ShowS #
Eq GCControl # |
Instance details Defined in HsLua.Core.Types Methods (==) :: GCControl -> GCControl -> Bool # (/=) :: GCControl -> GCControl -> Bool #
Ord GCControl # |
Instance details Defined in HsLua.Core.Types Methods compare :: GCControl -> GCControl -> Ordering # (<) :: GCControl -> GCControl -> Bool # (<=) :: GCControl -> GCControl -> Bool # (>) :: GCControl -> GCControl -> Bool # (>=) :: GCControl -> GCControl -> Bool # max :: GCControl -> GCControl -> GCControl # min :: GCControl -> GCControl -> GCControl #

gc :: GCControl -> LuaE e Int #

Controls the garbage collector.

This function performs several tasks, according to the given control command. See the documentation for `GCControl`.

Wraps `lua_gc`.

## miscellaneous and helper functions

next :: LuaError e => StackIndex -> LuaE e Bool #

Pops a key from the stack, and pushes a key–value pair from the table at the given index (the "next" pair after the given key). If there are no more elements in the table, then `next` returns `False` (and pushes nothing).

Errors on the Lua side are caught and rethrown as a ``Exception``.

This function wraps `hslua_next`. See also: lua_next.

error :: LuaE e NumResults #

Signals to Lua that an error has occurred and that the error object is at the top of the stack.

concat :: LuaError e => NumArgs -> LuaE e () #

Concatenates the `n` values at the top of the stack, pops them, and leaves the result at the top. If `n` is 1, the result is the single value on the stack (that is, the function does nothing); if `n` is 0, the result is the empty string. Concatenation is performed following the usual semantics of Lua (see §3.4.6 of the Lua manual).

Wraps `hslua_concat`. See also lua_concat.

pushglobaltable :: LuaE e () #

Pushes the global environment onto the stack.

Wraps `lua_pushglobaltable`.

register :: LuaError e => Name -> CFunction -> LuaE e () #

Sets the C function `f` as the new value of global `name`.

Behaves like "lua_register".

setwarnf #

Arguments

:: WarnFunction | f
-> Ptr () | ud
-> LuaE e () |

Sets the warning function to be used by Lua to emit warnings (see `WarnFunction`). The `ud` parameter sets the value `ud` passed to the warning function.

# loading libraries

openbase :: LuaError e => LuaE e () #

Pushes Lua's base library onto the stack.

This function pushes and and calls `luaopen_base`.

opendebug :: LuaError e => LuaE e () #

Pushes Lua's debug library onto the stack.

This function pushes and and calls `luaopen_io`.

openio :: LuaError e => LuaE e () #

Pushes Lua's io library onto the stack.

This function pushes and and calls `luaopen_io`.

openlibs :: LuaE e () #

Opens all standard Lua libraries into the current state and sets each library name as a global value.

This function wraps `luaL_openlibs`.

openmath :: LuaError e => LuaE e () #

Pushes Lua's math library onto the stack.

This function pushes and and calls `luaopen_math`.

openpackage :: LuaError e => LuaE e () #

Pushes Lua's package library onto the stack.

This function pushes and and calls `luaopen_package`.

openos :: LuaError e => LuaE e () #

Pushes Lua's os library onto the stack.

This function pushes and and calls `luaopen_os`.

openstring :: LuaError e => LuaE e () #

Pushes Lua's string library onto the stack.

This function pushes and and calls `luaopen_string`.

opentable :: LuaError e => LuaE e () #

Pushes Lua's table library onto the stack.

This function pushes and and calls `luaopen_table`.

# Auxiliary library

checkstack' #

Arguments

:: LuaError e |
=> Int | sz (requested additional size)
-> String | msg
-> LuaE e () |

Grows the stack size to `top + sz` elements, raising an error if the stack cannot grow to that size. `msg` is an additional text to go into the error message (or the empty string for no additional text).

dostring :: ByteString -> LuaE e Status #

Loads and runs the given string.

Returns `OK` on success, or an error if either loading of the string or calling of the thunk failed.

dofile :: Maybe FilePath -> LuaE e Status #

Loads and runs the given file. Note that the filepath is interpreted by Lua, not Haskell. The resulting chunk is named using the UTF8 encoded filepath.

getmetafield #

Arguments

:: StackIndex | obj
-> Name | e
-> LuaE e Type |

Pushes onto the stack the field `e` from the metatable of the object at index `obj` and returns the type of the pushed value. If the object does not have a metatable, or if the metatable does not have this field, pushes nothing and returns `TypeNil`.

Wraps `luaL_getmetafield`.

getmetatable' #

Arguments

:: Name | tname
-> LuaE e Type |

Pushes onto the stack the metatable associated with name `tname` in the registry (see `newmetatable`) (`nil` if there is no metatable associated with that name). Returns the type of the pushed value.

Wraps `luaL_getmetatable`.

getsubtable #

Arguments

:: LuaError e |
=> StackIndex | idx
-> Name | fname
-> LuaE e Bool |

Ensures that the value `t[fname]`, where `t` is the value at index `idx`, is a table, and pushes that table onto the stack. Returns True if it finds a previous table there and False if it creates a new table.

newmetatable :: Name -> LuaE e Bool #

If the registry already has the key tname, returns `False`. Otherwise, creates a new table to be used as a metatable for userdata, adds to this new table the pair `__name = tname`, adds to the registry the pair `[tname] = new table`, and returns `True`. (The entry `__name` is used by some error-reporting functions.)

In both cases pushes onto the stack the final value associated with `tname` in the registry.

The value of `tname` is used as a C string and hence must not contain null bytes.

Wraps `luaL_newmetatable`.

requiref #

Arguments

:: LuaError e |
=> Name | modname
-> CFunction | openf
-> Bool | glb
-> LuaE e () |

If `modname` is not already present in `package.loaded`. calls function `openf` with string `modname` as an argument and sets the call result in `package.loaded[modname]`, as if that function has been called through require.

If `glb` is true, also stores the module into global `modname`.

Leaves a copy of the module on the stack.

See `requirehs` for a version intended to be used with Haskell actions.

tostring' :: LuaError e => StackIndex -> LuaE e ByteString #

Converts any Lua value at the given index to a `ByteString` in a reasonable format. The resulting string is pushed onto the stack and also returned by the function.

If the value has a metatable with a `__tostring` field, then `tolstring'` calls the corresponding metamethod with the value as argument, and uses the result of the call as its result.

Wraps `hsluaL_tolstring`.

traceback :: State -> Maybe ByteString -> Int -> LuaE e () #

Creates and pushes a traceback of the stack L1. If a message is given it is appended at the beginning of the traceback. The level parameter tells at which level to start the traceback.

Wraps `luaL_traceback`.

where' #

Arguments

:: Int | lvl
-> LuaE e () |

Pushes onto the stack a string identifying the current position of the control at level `lvl` in the call stack. Typically this string has the following format:

    chunkname:currentline:

Level 0 is the running function, level 1 is the function that called the running function, etc.

This function is used to build a prefix for error messages.

## References

data Reference #

Reference to a stored value.

Constructors

Reference CInt | Reference to a stored value
RefNil | Reference to a nil value

#### Instances

Instances details

Show Reference |
Instance details Defined in Lua.Auxiliary Methods showsPrec :: Int -> Reference -> ShowS # show :: Reference -> String # showList :: [Reference] -> ShowS #
Eq Reference |
Instance details Defined in Lua.Auxiliary Methods (==) :: Reference -> Reference -> Bool # (/=) :: Reference -> Reference -> Bool #

ref :: StackIndex -> LuaE e Reference #

Creates and returns a reference, in the table at index `t`, for the object at the top of the stack (and pops the object).

A reference is a unique integer key. As long as you do not manually add integer keys into table `t`, `ref` ensures the uniqueness of the key it returns. You can retrieve an object referred by reference `r` by calling `rawgeti t r`. Function ``unref`` frees a reference and its associated object.

If the object at the top of the stack is nil, ``ref`` returns the constant ``refnil``. The constant ``noref`` is guaranteed to be different from any reference returned by ``ref``.

Wraps `luaL_ref`.

getref :: LuaError e => StackIndex -> Reference -> LuaE e Type #

Push referenced value from the table at the given index.

unref #

Arguments

:: StackIndex | idx
-> Reference | ref
-> LuaE e () |

Releases reference ``ref`` from the table at index `idx` (see ``ref``). The entry is removed from the table, so that the referred object can be collected. The reference ``ref`` is also freed to be used again.

Wraps `luaL_unref`. See also: luaL_unref.

fromReference :: Reference -> CInt #

Convert a reference to its C representation.

toReference :: CInt -> Reference #

Create a reference from its C representation.

noref :: Int #

Value signaling that no reference was found.

refnil :: Int #

Value signaling that no reference was created.

## Registry fields

loaded :: Name #

Key to the registry field that holds the table of loaded modules.

preload :: Name #

Key to the registry field that holds the table of loader functions.

## Running with tracebacks

pcallTrace :: NumArgs -> NumResults -> LuaE e Status #

Like ``pcall``, but sets an appropriate message handler function, thereby adding a stack traceback if an error occurs.

callTrace :: LuaError e => NumArgs -> NumResults -> LuaE e () #

Like ``call``, but adds a traceback if an error occurs.

dofileTrace :: Maybe FilePath -> LuaE e Status #

Run the given file as a Lua program, while also adding a traceback to the error message if an error occurs.

dostringTrace :: ByteString -> LuaE e Status #

## Warnings

setwarnf' :: LuaError e => (ByteString -> LuaE e ()) -> LuaE e () #

Sets a warning function. This is a simplified version of `lua_setwarnf`. The given function is called with the concatenated warning components as the single argument.

Control messages are handled internally and are not passed on the warning hook. As with the default warning function, the control messages `@on` and `@off` can switch error reporting to stderr on and off. The given Haskell function will be called in either case, even when the error is not written to stderr.

Wraps `hsluaL_setwarnf`.

# Debug interface

getupvalue #

Arguments

:: StackIndex | funcindex
-> Int | n
-> LuaE e (Maybe Name) |

Gets information about the `n`-th upvalue of the closure at index `funcindex`. It pushes the upvalue's value onto the stack and returns its name. Returns `Nothing` (and pushes nothing) when the index `n` is greater than the number of upvalues.

See debug.getupvalue for more information about upvalues.

    [0, +(0|1), -]

Wraps `lua_getupvalue`.

setupvalue #

Arguments

:: StackIndex | funcindex
-> Int | n
-> LuaE e (Maybe Name) |

Sets the value of a closure’s upvalue. It assigns the value on the top of the stack to the upvalue and returns its name. It also pops the value from the stack.

Returns `Nothing` (and pops nothing) when the index `n` is greater than the number of upvalues.

Parameters `funcindex` and `n` are as in the function `getupvalue`.

    [-(0|1), +0, -]

Wraps `lua_setupvalue`.

# Haskell userdata values

Push arbitrary Haskell values to the Lua stack.

newhsuserdatauv #

Arguments

:: a | Haskell object
-> Int | number of extra userdata values
-> LuaE e () |

Creates a new userdata wrapping the given Haskell object. The userdata is pushed to the top of the stack.

newudmetatable :: Name -> LuaE e Bool #

Creates and registers a new metatable for a userdata-wrapped Haskell value; checks whether a metatable of that name has been registered yet and uses the registered table if possible.

Returns `True` if a new metatable was created, and `False` otherwise.

Using a metatable created by this functions ensures that the pointer to the Haskell value will be freed when the userdata object is garbage collected in Lua.

The name may not contain a nul character.

fromuserdata #

Arguments

:: forall a e. StackIndex | stack index of userdata
-> Name | expected name of userdata object
-> LuaE e (Maybe a) |

Retrieves a Haskell object from userdata at the given index. The userdata must have the given name.

putuserdata #

Arguments

:: StackIndex | index
-> Name | name
-> a | new value
-> LuaE e Bool |

Replaces the Haskell value contained in the userdata value at `index`. Checks that the userdata is of type `name` and returns `True` on success, or `False` otherwise.

## Haskell functions and closures

type HaskellFunction e = LuaE e NumResults #

Haskell function that can be called from Lua. The HsLua equivallent of a `PreCFunction`.

pushHaskellFunction :: LuaError e => HaskellFunction e -> LuaE e () #

Pushes Haskell function as a callable userdata. All values created will be garbage collected. The function should behave similar to a `CFunction`.

Error conditions should be indicated by raising a catchable exception or by returning the result of ``error``.

Example:

    mod23 :: Lua NumResults
    mod23 = do
      mn <- tointeger (nthBottom 1)
      case mn of
        Nothing -> pushstring "expected an integer" *> error
        Just n  -> pushinteger (n `mod` 23)
    pushHaskellFunction mod23
    setglobal "mod23"

pushPreCFunction :: PreCFunction -> LuaE e () #

Converts a pre C function to a Lua function and pushes it to the stack.

Pre C functions collect parameters from the stack and return a `CInt` that represents number of return values left on the stack. See `CFunction` for more info.

# Error handling

class Exception e => LuaError e where #

Any type that you wish to use for error handling in HsLua must be an instance of the `LuaError` class.

Methods

popException :: LuaE e e #

Converts the error at the top of the stack into an exception and pops the error off the stack.

This function is expected to produce a valid result for any Lua value; neither a Haskell exception nor a Lua error may result when this is called.

pushException :: e -> LuaE e () #

Pushes an exception to the top of the Lua stack. The pushed Lua object is used as an error object, and it is recommended that calling `tostring()` on the object produces an informative message.

luaException :: String -> e #

Creates a new exception with the given message.

#### Instances

Instances details

LuaError Exception # |
Instance details Defined in HsLua.Core.Error Methods popException :: LuaE Exception Exception # pushException :: Exception -> LuaE Exception () # luaException :: String -> Exception #

newtype Exception #

Default Lua error type. Exceptions raised by Lua-related operations.

Constructors

Exception |
Fields exceptionMessage :: String

#### Instances

Instances details

Exception Exception # |
Instance details Defined in HsLua.Core.Error Methods toException :: Exception -> SomeException # fromException :: SomeException -> Maybe Exception # displayException :: Exception -> String # backtraceDesired :: Exception -> Bool #
Show Exception # |
Instance details Defined in HsLua.Core.Error Methods showsPrec :: Int -> Exception -> ShowS # show :: Exception -> String # showList :: [Exception] -> ShowS #
Eq Exception # |
Instance details Defined in HsLua.Core.Error Methods (==) :: Exception -> Exception -> Bool # (/=) :: Exception -> Exception -> Bool #
LuaError Exception # |
Instance details Defined in HsLua.Core.Error Methods popException :: LuaE Exception Exception # pushException :: Exception -> LuaE Exception () # luaException :: String -> Exception #

try :: Exception e => LuaE e a -> LuaE e (Either e a) #

Return either the result of a Lua computation or, if an exception was thrown, the error.

failLua :: LuaError e => String -> LuaE e a #

Raises an exception in the Lua monad.

throwErrorAsException :: LuaError e => LuaE e a #

Converts a Lua error at the top of the stack into a Haskell exception and throws it.

throwTypeMismatchError :: LuaError e => ByteString -> StackIndex -> LuaE e a #

Raises an exception that's appropriate when the type of a Lua object at the given index did not match the expected type. The name or description of the expected type is taken as an argument.

changeErrorType :: forall old new a. LuaE old a -> LuaE new a #

Change the error type of a computation.

## Helpers

popErrorMessage :: State -> IO ByteString #

Retrieve and pop the top object as an error message. This is very similar to tostring', but ensures that we don't recurse if getting the message failed.

This helpful as a "last resort" method when implementing `popException`.

pushTypeMismatchError #

Arguments

:: ByteString | name or description of expected type
-> StackIndex | stack index of mismatching object
-> LuaE e () |

Creates an error to notify about a Lua type mismatch and pushes it to the stack.

# Package

requirehs #

Arguments

:: LuaError e |
=> Name | modname
-> (Name -> LuaE e ()) | openf
-> LuaE e () |

Load a module, defined by a Haskell action, under the given name.

Similar to `luaL_requiref`: If `modname` is not already present in `package.loaded`, calls function `openf` with string `modname` as an argument and sets the call result in `package.loaded[modname]`, as if that function has been called through require.

Leaves a copy of the module on the stack.

preloadhs :: LuaError e => Name -> LuaE e NumResults -> LuaE e () #

Registers a preloading function. Takes an module name and the Lua operation which produces the package.