lua-2.1.0: Lua, an embeddable scripting language

Copyright | © 2021-2022 Albert Krewinkel
License | MIT
Maintainer | Albert Krewinkel <tarleb+hslua@zeitkraut.de>
Stability | beta
Portability | portable
Safe Haskell | None
Language | Haskell2010

Lua

Contents

- Run Lua operations
- Types
  - Base Lua types
    - Booleans
  - Stack indices
  - Function calling
  - Basic types
  - Relational operator codes
  - Codes for arithmetic operations
  - Status codes
- Stack index helpers
- Functions
  - State manipulation
  - Basic stack manipulation
  - Access functions (stack → Haskell)
  - Push functions (Haskell → stack)
  - Get functions (Lua → stack)
  - Set functions (stack → Lua)
  - Misc (safe)
  - Misc (unsafe)
  - Load and run Lua code
  - Coroutine functions
  - Garbage-collection
  - Miscellaneous functions
- The Auxiliary Library
  - Registry fields
  - References
- Ersatz functions
  - Get functions (Lua → stack)
  - Set functions (stack → Lua)
  - Misc
- Standard Lua libraries
- Push Haskell functions

Description

Extend Haskell programs with a Lua interpreter.

This package provides the basic building blocks to integrate Lua into a Haskell program. The library is kept very close to the C Lua API, and users familiar with the C API should have no problem using it.

However, there are important differences of which users must be aware: The method for error signaling used in Lua, based on `setjmp` and `longjmp`, is incompatible with the Haskell FFI. All errors must be handled at language boundaries, as failure to do so will lead to unrecoverable crashes. C API functions that can throw Lua errors are still exported, but non-error throwing `hslua_` versions are provided as safer alternatives. . The `hslua` ersatz functions have worse performance than the original versions, but should be fast enough for most use cases.

The Haskell FFI requires all C function that can call back into Haskell to be imported `safe`ly. Some of the Lua functions may, directly or indirectly, call a Haskell function, so they are always imported with the `safe` keyword.

Many API functions can trigger garbage collection. This will lead to problems if Haskell functions are used as part of finalizers (i.e., `__gc` metamethods). Haskell in finalizers is not supported by default, but can be enabled by unsetting the `allow-unsafe-gc` flag.

Synopsis

- withNewState :: (State -> IO a) -> IO a
- newtype State = State (Ptr ())
- type Reader = FunPtr (State -> Ptr () -> Ptr CSize -> IO (Ptr CChar))
- type CFunction = FunPtr PreCFunction
- type PreCFunction = State -> IO NumResults
- newtype Integer = Integer Int64
- newtype Number = Number Double
- newtype LuaBool = LuaBool CInt
- pattern TRUE :: LuaBool
- pattern FALSE :: LuaBool
- newtype StackIndex = StackIndex {
  - fromStackIndex :: CInt
  }
- pattern LUA_REGISTRYINDEX :: StackIndex
- newtype NumArgs = NumArgs {
  - fromNumArgs :: CInt
  }
- newtype NumResults = NumResults {
  - fromNumResults :: CInt
  }
- pattern LUA_MULTRET :: NumResults
- newtype TypeCode = TypeCode {
  - fromTypeCode :: CInt
  }
- pattern LUA_TNONE :: TypeCode
- pattern LUA_TNIL :: TypeCode
- pattern LUA_TBOOLEAN :: TypeCode
- pattern LUA_TLIGHTUSERDATA :: TypeCode
- pattern LUA_TNUMBER :: TypeCode
- pattern LUA_TSTRING :: TypeCode
- pattern LUA_TTABLE :: TypeCode
- pattern LUA_TFUNCTION :: TypeCode
- pattern LUA_TUSERDATA :: TypeCode
- pattern LUA_TTHREAD :: TypeCode
- newtype OPCode = OPCode CInt
- pattern LUA_OPEQ :: OPCode
- pattern LUA_OPLT :: OPCode
- pattern LUA_OPLE :: OPCode
- pattern LUA_OPADD :: ArithOPCode
- pattern LUA_OPSUB :: ArithOPCode
- pattern LUA_OPMUL :: ArithOPCode
- pattern LUA_OPDIV :: ArithOPCode
- pattern LUA_OPIDIV :: ArithOPCode
- pattern LUA_OPMOD :: ArithOPCode
- pattern LUA_OPPOW :: ArithOPCode
- pattern LUA_OPUNM :: ArithOPCode
- pattern LUA_OPBNOT :: ArithOPCode
- pattern LUA_OPBAND :: ArithOPCode
- pattern LUA_OPBOR :: ArithOPCode
- pattern LUA_OPBXOR :: ArithOPCode
- pattern LUA_OPSHL :: ArithOPCode
- pattern LUA_OPSHR :: ArithOPCode
- newtype StatusCode = StatusCode CInt
- pattern LUA_OK :: StatusCode
- pattern LUA_YIELD :: StatusCode
- pattern LUA_ERRRUN :: StatusCode
- pattern LUA_ERRSYNTAX :: StatusCode
- pattern LUA_ERRMEM :: StatusCode
- pattern LUA_ERRGCMM :: StatusCode
- pattern LUA_ERRERR :: StatusCode
- pattern LUA_ERRFILE :: StatusCode
- nthTop :: CInt -> StackIndex
- nthBottom :: CInt -> StackIndex
- nth :: CInt -> StackIndex
- top :: StackIndex
- lua_close :: State -> IO ()
- lua_newthread :: State -> IO State
- lua_version :: State -> IO (Ptr Number)
- lua_absindex :: State -> StackIndex -> IO StackIndex
- lua_gettop :: State -> IO StackIndex
- lua_settop :: State -> StackIndex -> IO ()
- lua_pushvalue :: State -> StackIndex -> IO ()
- lua_pop :: State -> CInt -> IO ()
- lua_copy :: State -> StackIndex -> StackIndex -> IO ()
- lua_remove :: State -> StackIndex -> IO ()
- lua_insert :: State -> StackIndex -> IO ()
- lua_replace :: State -> StackIndex -> IO ()
- lua_rotate :: State -> StackIndex -> CInt -> IO ()
- lua_checkstack :: State -> CInt -> IO LuaBool
- lua_isnil :: State -> StackIndex -> IO LuaBool
- lua_isboolean :: State -> StackIndex -> IO LuaBool
- lua_isnumber :: State -> StackIndex -> IO LuaBool
- lua_isinteger :: State -> StackIndex -> IO LuaBool
- lua_isstring :: State -> StackIndex -> IO LuaBool
- lua_isfunction :: State -> StackIndex -> IO LuaBool
- lua_istable :: State -> StackIndex -> IO LuaBool
- lua_iscfunction :: State -> StackIndex -> IO LuaBool
- lua_isuserdata :: State -> StackIndex -> IO LuaBool
- lua_islightuserdata :: State -> StackIndex -> IO LuaBool
- lua_isthread :: State -> StackIndex -> IO LuaBool
- lua_isnone :: State -> StackIndex -> IO LuaBool
- lua_isnoneornil :: State -> StackIndex -> IO LuaBool
- lua_type :: State -> StackIndex -> IO TypeCode
- lua_typename :: State -> TypeCode -> IO CString
- lua_rawequal :: State -> StackIndex -> StackIndex -> IO LuaBool
- lua_toboolean :: State -> StackIndex -> IO LuaBool
- lua_tocfunction :: State -> StackIndex -> IO CFunction
- lua_tointegerx :: State -> StackIndex -> Ptr LuaBool -> IO Integer
- lua_tonumberx :: State -> StackIndex -> Ptr LuaBool -> IO Number
- lua_tolstring :: State -> StackIndex -> Ptr CSize -> IO (Ptr CChar)
- lua_topointer :: State -> StackIndex -> IO (Ptr ())
- lua_tothread :: State -> StackIndex -> IO State
- lua_touserdata :: State -> StackIndex -> IO (Ptr a)
- lua_rawlen :: State -> StackIndex -> IO CSize
- lua_pushnil :: State -> IO ()
- lua_pushnumber :: State -> Number -> IO ()
- lua_pushinteger :: State -> Integer -> IO ()
- lua_pushlstring :: State -> Ptr CChar -> CSize -> IO ()
- lua_pushstring :: State -> CString -> IO CString
- lua_pushcclosure :: State -> CFunction -> NumArgs -> IO ()
- lua_pushcfunction :: State -> CFunction -> IO ()
- lua_pushboolean :: State -> LuaBool -> IO ()
- lua_pushlightuserdata :: State -> Ptr a -> IO ()
- lua_pushthread :: State -> IO CInt
- lua_rawget :: State -> StackIndex -> IO TypeCode
- lua_rawgeti :: State -> StackIndex -> Integer -> IO TypeCode
- lua_createtable :: State -> CInt -> CInt -> IO ()
- lua_newuserdata :: State -> CSize -> IO (Ptr ())
- lua_getmetatable :: State -> StackIndex -> IO LuaBool
- lua_getuservalue :: State -> StackIndex -> IO TypeCode
- lua_getglobal :: State -> CString -> IO TypeCode
- lua_gettable :: State -> StackIndex -> IO TypeCode
- lua_rawset :: State -> StackIndex -> IO ()
- lua_rawseti :: State -> StackIndex -> Integer -> IO ()
- lua_setmetatable :: State -> StackIndex -> IO ()
- lua_setuservalue :: State -> StackIndex -> IO ()
- lua_setglobal :: State -> CString -> IO ()
- lua_settable :: State -> StackIndex -> IO ()
- lua_stringtonumber :: State -> CString -> IO CSize
- lua_arith :: State -> ArithOPCode -> IO ()
- lua_concat :: State -> CInt -> IO ()
- lua_next :: State -> StackIndex -> IO LuaBool
- lua_pcall :: State -> NumArgs -> NumResults -> StackIndex -> IO StatusCode
- lua_load :: State -> Reader -> Ptr () -> CString -> CString -> IO StatusCode
- lua_status :: State -> IO StatusCode
- lua_gc :: State -> GCCode -> CInt -> IO CInt
- newtype GCCode = GCCode CInt
- pattern LUA_GCSTOP :: GCCode
- pattern LUA_GCRESTART :: GCCode
- pattern LUA_GCCOLLECT :: GCCode
- pattern LUA_GCCOUNT :: GCCode
- pattern LUA_GCCOUNTB :: GCCode
- pattern LUA_GCSTEP :: GCCode
- pattern LUA_GCSETPAUSE :: GCCode
- pattern LUA_GCSETSTEPMUL :: GCCode
- pattern LUA_GCISRUNNING :: GCCode
- lua_pushglobaltable :: State -> IO ()
- luaL_getmetafield :: State -> StackIndex -> CString -> IO TypeCode
- luaL_getmetatable :: State -> CString -> IO TypeCode
- luaL_loadbuffer :: State -> Ptr CChar -> CSize -> CString -> IO StatusCode
- luaL_openlibs :: State -> IO ()
- luaL_newmetatable :: State -> CString -> IO LuaBool
- luaL_ref :: State -> StackIndex -> IO CInt
- luaL_testudata :: State -> StackIndex -> CString -> IO (Ptr ())
- luaL_traceback :: State -> State -> CString -> CInt -> IO ()
- luaL_unref :: State -> StackIndex -> CInt -> IO ()
- loadedTableRegistryField :: String
- preloadTableRegistryField :: String
- data Reference
  - = Reference CInt
  - | RefNil
- pattern LUA_REFNIL :: CInt
- pattern LUA_NOREF :: CInt
- fromReference :: Reference -> CInt
- toReference :: CInt -> Reference
- hsluaL_newstate :: IO State
- hsluaL_tolstring :: State -> StackIndex -> Ptr CSize -> IO (Ptr CChar)
- hsluaL_requiref :: State -> Ptr CChar -> CFunction -> LuaBool -> Ptr StatusCode -> IO ()
- hslua_gettable :: State -> StackIndex -> Ptr StatusCode -> IO TypeCode
- hslua_getglobal :: State -> CString -> CSize -> Ptr StatusCode -> IO TypeCode
- hslua_settable :: State -> StackIndex -> Ptr StatusCode -> IO ()
- hslua_setglobal :: State -> CString -> CSize -> Ptr StatusCode -> IO ()
- hslua_error :: State -> IO NumResults
- hslua_next :: State -> StackIndex -> Ptr StatusCode -> IO LuaBool
- hslua_concat :: State -> NumArgs -> Ptr StatusCode -> IO ()
- hslua_arith :: State -> ArithOPCode -> Ptr StatusCode -> IO ()
- hslua_compare :: State -> StackIndex -> StackIndex -> OPCode -> Ptr StatusCode -> IO LuaBool
- luaopen_base :: CFunction
- luaopen_table :: CFunction
- luaopen_io :: CFunction
- luaopen_os :: CFunction
- luaopen_string :: CFunction
- luaopen_math :: CFunction
- luaopen_debug :: CFunction
- luaopen_package :: CFunction
- hslua_pushhsfunction :: State -> PreCFunction -> IO ()

# Run Lua operations

withNewState :: (State -> IO a) -> IO a #

Runs operations on a new Lua ``State``. The state is created when the function is called and closed on return. The state, and all pointers to values within it, must not be used after the function returns.

### Example

Run a small Lua operation (prints the major version of Lua).

    withNewState $ \l -> do
      luaL_openlibs l
      withCString "print" (lua_getglobal l)
      withCString "_VERSION" (lua_getglobal l)
      lua_pcall l (NumArgs 1) (NumResults 1) (StackIndex 0)

Since: 2.0.0

# Types

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

Eq State # |
Instance details Defined in Lua.Types Methods (==) :: State -> State -> Bool # (/=) :: State -> State -> Bool #
Generic State # |
Instance details Defined in Lua.Types Associated Types type Rep State :: Type -> Type # Methods from :: State -> Rep State x # to :: Rep State x -> State #
type Rep State # |
Instance details Defined in Lua.Types type Rep State = D1 ('MetaData "State" "Lua.Types" "lua-2.1.0-KFi2qUEupCPKdlnmEYIKQz" 'True) (C1 ('MetaCons "State" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Ptr ()))))

type Reader = FunPtr (State -> Ptr () -> Ptr CSize -> IO (Ptr CChar)) #

The reader function used by ``load``. Every time it needs another piece of the chunk, lua_load calls the reader, passing along its data parameter. The reader must return a pointer to a block of memory with a new piece of the chunk and set size to the block size. The block must exist until the reader function is called again. To signal the end of the chunk, the reader must return `NULL` or set size to zero. The reader function may return pieces of any size greater than zero.

See lua_Reader.

## Base Lua 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] #
Eq Integer # |
Instance details Defined in Lua.Types Methods (==) :: Integer -> Integer -> Bool # (/=) :: Integer -> Integer -> Bool #
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 -> Integer0 #
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 :: Integer0 -> Integer #
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 #
Read Integer # |
Instance details Defined in Lua.Types Methods readsPrec :: Int -> ReadS Integer # readList :: ReadS [Integer] # readPrec :: ReadPrec Integer # readListPrec :: ReadPrec [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 #

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

Eq Number # |
Instance details Defined in Lua.Types Methods (==) :: Number -> Number -> Bool # (/=) :: Number -> Number -> Bool #
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 #
Fractional Number # |
Instance details Defined in Lua.Types Methods (/) :: Number -> Number -> Number # recip :: Number -> Number # fromRational :: Rational -> 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 #
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 #
Read Number # |
Instance details Defined in Lua.Types Methods readsPrec :: Int -> ReadS Number # readList :: ReadS [Number] # readPrec :: ReadPrec Number # readListPrec :: ReadPrec [Number] #
Real Number # |
Instance details Defined in Lua.Types Methods toRational :: Number -> Rational #
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 #
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 #

### Booleans

newtype LuaBool #

Boolean value returned by a Lua C API function. This is a ``CInt`` and should be interpreted as ``False`` iff the value is `0`, ``True`` otherwise.

Constructors

LuaBool CInt |

#### Instances

Instances details

Eq LuaBool # |
Instance details Defined in Lua.Types Methods (==) :: LuaBool -> LuaBool -> Bool # (/=) :: LuaBool -> LuaBool -> Bool #
Show LuaBool # |
Instance details Defined in Lua.Types Methods showsPrec :: Int -> LuaBool -> ShowS # show :: LuaBool -> String # showList :: [LuaBool] -> ShowS #
Storable LuaBool # |
Instance details Defined in Lua.Types Methods sizeOf :: LuaBool -> Int # alignment :: LuaBool -> Int # peekElemOff :: Ptr LuaBool -> Int -> IO LuaBool # pokeElemOff :: Ptr LuaBool -> Int -> LuaBool -> IO () # peekByteOff :: Ptr b -> Int -> IO LuaBool # pokeByteOff :: Ptr b -> Int -> LuaBool -> IO () # peek :: Ptr LuaBool -> IO LuaBool # poke :: Ptr LuaBool -> LuaBool -> IO () #

pattern TRUE :: LuaBool #

Value which Lua usually uses as `True`.

pattern FALSE :: LuaBool #

Value which Lua usually uses as `False`.

## Stack indices

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

pattern LUA_REGISTRYINDEX :: StackIndex #

Stack index of the Lua registry.

## Function calling

newtype NumArgs #

The number of arguments consumed curing a function call.

Constructors

NumArgs |
Fields fromNumArgs :: CInt

#### Instances

Instances details

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

newtype NumResults #

The number of results returned by a function call.

Constructors

NumResults |
Fields fromNumResults :: CInt

#### Instances

Instances details

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

pattern LUA_MULTRET :: NumResults #

Option for multiple returns in ``lua_pcall``.

## Basic types

newtype TypeCode #

Integer code used to encode the type of a Lua value.

Constructors

TypeCode |
Fields fromTypeCode :: CInt

#### Instances

Instances details

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

pattern LUA_TNONE :: TypeCode #

Non-valid stack index

pattern LUA_TNIL :: TypeCode #

Type of Lua's `nil` value

pattern LUA_TBOOLEAN :: TypeCode #

Type of Lua booleans

pattern LUA_TLIGHTUSERDATA :: TypeCode #

Type of light userdata

pattern LUA_TNUMBER :: TypeCode #

Type of Lua numbers. See ``Number``

pattern LUA_TSTRING :: TypeCode #

Type of Lua string values

pattern LUA_TTABLE :: TypeCode #

Type of Lua tables

pattern LUA_TFUNCTION :: TypeCode #

Type of functions, either normal or ``CFunction``

pattern LUA_TUSERDATA :: TypeCode #

Type of full user data

pattern LUA_TTHREAD :: TypeCode #

Type of Lua threads

## Relational operator codes

newtype OPCode #

Relational operator code.

Constructors

OPCode CInt |

#### Instances

Instances details

Eq OPCode # |
Instance details Defined in Lua.Types Methods (==) :: OPCode -> OPCode -> Bool # (/=) :: OPCode -> OPCode -> Bool #
Show OPCode # |
Instance details Defined in Lua.Types Methods showsPrec :: Int -> OPCode -> ShowS # show :: OPCode -> String # showList :: [OPCode] -> ShowS #
Storable OPCode # |
Instance details Defined in Lua.Types Methods sizeOf :: OPCode -> Int # alignment :: OPCode -> Int # peekElemOff :: Ptr OPCode -> Int -> IO OPCode # pokeElemOff :: Ptr OPCode -> Int -> OPCode -> IO () # peekByteOff :: Ptr b -> Int -> IO OPCode # pokeByteOff :: Ptr b -> Int -> OPCode -> IO () # peek :: Ptr OPCode -> IO OPCode # poke :: Ptr OPCode -> OPCode -> IO () #

pattern LUA_OPEQ :: OPCode #

Compares for equality (==)

pattern LUA_OPLT :: OPCode #

Compares for less than (<)

pattern LUA_OPLE :: OPCode #

Compares for less or equal (<=)

## Codes for arithmetic operations

pattern LUA_OPADD :: ArithOPCode #

Performs addition (`+`).

pattern LUA_OPSUB :: ArithOPCode #

Performs subtraction (`-`)

pattern LUA_OPMUL :: ArithOPCode #

Performs multiplication (`*`)

pattern LUA_OPDIV :: ArithOPCode #

Performs float division (`/`)

pattern LUA_OPIDIV :: ArithOPCode #

Performs floor division (`//`)

pattern LUA_OPMOD :: ArithOPCode #

Performs modulo (`%`)

pattern LUA_OPPOW :: ArithOPCode #

Performs exponentiation (`^`)

pattern LUA_OPUNM :: ArithOPCode #

Performs mathematical negation (unary `-`)

pattern LUA_OPBNOT :: ArithOPCode #

Performs bitwise NOT (`~`)

pattern LUA_OPBAND :: ArithOPCode #

Performs bitwise AND (`&`)

pattern LUA_OPBOR :: ArithOPCode #

Performs bitwise OR (`|`)

pattern LUA_OPBXOR :: ArithOPCode #

Performs bitwise exclusive OR (`~`)

pattern LUA_OPSHL :: ArithOPCode #

Performs left shift (`<<`)

pattern LUA_OPSHR :: ArithOPCode #

Performs right shift (`>>`)

## Status codes

newtype StatusCode #

Integer code used to signal the status of a thread or computation.

Constructors

StatusCode CInt |

#### Instances

Instances details

Eq StatusCode # |
Instance details Defined in Lua.Types Methods (==) :: StatusCode -> StatusCode -> Bool # (/=) :: StatusCode -> StatusCode -> Bool #
Show StatusCode # |
Instance details Defined in Lua.Types Methods showsPrec :: Int -> StatusCode -> ShowS # show :: StatusCode -> String # showList :: [StatusCode] -> ShowS #
Storable StatusCode # |
Instance details Defined in Lua.Types Methods sizeOf :: StatusCode -> Int # alignment :: StatusCode -> Int # peekElemOff :: Ptr StatusCode -> Int -> IO StatusCode # pokeElemOff :: Ptr StatusCode -> Int -> StatusCode -> IO () # peekByteOff :: Ptr b -> Int -> IO StatusCode # pokeByteOff :: Ptr b -> Int -> StatusCode -> IO () # peek :: Ptr StatusCode -> IO StatusCode # poke :: Ptr StatusCode -> StatusCode -> IO () #

pattern LUA_OK :: StatusCode #

Success.

pattern LUA_YIELD :: StatusCode #

Yielding / suspended coroutine.

pattern LUA_ERRRUN :: StatusCode #

A runtime error.

pattern LUA_ERRSYNTAX :: StatusCode #

A syntax error.

pattern LUA_ERRMEM :: StatusCode #

Memory allocation error. For such errors, Lua does not call the message handler.

pattern LUA_ERRGCMM :: StatusCode #

Error while running a `__gc` metamethod. For such errors, Lua does not call the message handler (as this kind of error typically has no relation with the function being called).

pattern LUA_ERRERR :: StatusCode #

Error while running the message handler.

pattern LUA_ERRFILE :: StatusCode #

File related error (e.g., the file cannot be opened or read).

# Stack index helpers

nthTop :: CInt -> StackIndex #

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

Since: 2.0.0

nthBottom :: CInt -> StackIndex #

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

Since: 2.0.0

nth :: CInt -> StackIndex #

Alias for `nthTop`.

Since: 2.0.0

top :: StackIndex #

Index of the topmost stack element.

Since: 2.0.0

# Functions

## State manipulation

lua_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. In 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.

https://www.lua.org/manual/5.3/manual.html#lua_close

lua_newthread :: State -> IO State #

Creates a new thread, pushes it on the stack, and returns a `State` that represents this new thread. The new thread returned by this function shares with the original thread its global environment, but has an independent execution stack.

There is no explicit function to close or to destroy a thread. Threads are subject to garbage collection, like any Lua object.

https://www.lua.org/manual/5.3/manual.html#lua_newthread

lua_version :: State -> IO (Ptr Number) #

Returns the address of the version number (a C static variable) stored in the Lua core. When called with a valid `State`, returns the address of the version used to create that state. When called with `NULL`, returns the address of the version running the call.

https://www.lua.org/manual/5.3/manual.html#lua_version

## Basic stack manipulation

lua_absindex #

Arguments

:: State |
-> StackIndex | idx
-> IO StackIndex |

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

https://www.lua.org/manual/5.3/manual.html#lua_absindex

lua_gettop :: State -> IO 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).

https://www.lua.org/manual/5.3/manual.html#lua_gettop

lua_settop #

Arguments

:: State |
-> StackIndex | index
-> IO () |

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.

https://www.lua.org/manual/5.3/manual.html#lua_settop

lua_pushvalue :: State -> StackIndex -> IO () #

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

https://www.lua.org/manual/5.3/manual.html#lua_pushvalue

lua_pop #

Arguments

:: State |
-> CInt | n
-> IO () |

Pops `n` elements from the stack.

https://www.lua.org/manual/5.3/manual.html#lua_pop

lua_copy #

Arguments

:: State |
-> StackIndex | fromidx
-> StackIndex | toidx
-> IO () |

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

https://www.lua.org/manual/5.3/manual.html#lua_copy

lua_remove :: State -> StackIndex -> IO () #

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.

https://www.lua.org/manual/5.3/manual.html#lua_remove

lua_insert :: State -> StackIndex -> IO () #

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.

https://www.lua.org/manual/5.3/manual.html#lua_insert

lua_replace :: State -> StackIndex -> IO () #

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.

https://www.lua.org/manual/5.3/manual.html#lua_replace

lua_rotate #

Arguments

:: State |
-> StackIndex | idx
-> CInt | n
-> IO () |

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/5.3/manual.html#lua_rotate

lua_checkstack #

Arguments

:: State |
-> CInt | n
-> IO LuaBool |

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.

https://www.lua.org/manual/5.3/manual.html#lua_checkstack

## Access functions (stack → Haskell)

lua_isnil :: State -> StackIndex -> IO LuaBool #

Returns ``TRUE`` if the value at the given index is nil, and ``FALSE`` otherwise.

https://www.lua.org/manual/5.3/manual.html#lua_isnil

lua_isboolean :: State -> StackIndex -> IO LuaBool #

Returns ``TRUE`` if the value at the given index is a boolean, and ``FALSE`` otherwise.

https://www.lua.org/manual/5.3/manual.html#lua_isboolean

lua_isnumber :: State -> StackIndex -> IO LuaBool #

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

https://www.lua.org/manual/5.3/manual.html#lua_isnumber

lua_isinteger :: State -> StackIndex -> IO LuaBool #

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.

https://www.lua.org/manual/5.3/manual.html#lua_isinteger

lua_isstring :: State -> StackIndex -> IO LuaBool #

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.

https://www.lua.org/manual/5.3/manual.html#lua_isstring

lua_isfunction :: State -> StackIndex -> IO LuaBool #

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

https://www.lua.org/manual/5.3/manual.html#lua_isfunction

lua_istable :: State -> StackIndex -> IO LuaBool #

Returns ``TRUE`` if the value at the given index is a table, and ``FALSE`` otherwise.

https://www.lua.org/manual/5.3/manual.html#lua_istable

lua_iscfunction :: State -> StackIndex -> IO LuaBool #

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

https://www.lua.org/manual/5.3/manual.html#lua_iscfunction

lua_isuserdata :: State -> StackIndex -> IO LuaBool #

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

https://www.lua.org/manual/5.3/manual.html#lua_isuserdata

lua_islightuserdata :: State -> StackIndex -> IO LuaBool #

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

https://www.lua.org/manual/5.3/manual.html#lua_islightuserdata

lua_isthread :: State -> StackIndex -> IO LuaBool #

Returns ``TRUE`` if the value at the given index is a thread, and ``FALSE`` otherwise.

https://www.lua.org/manual/5.3/manual.html#lua_isthread

lua_isnone :: State -> StackIndex -> IO LuaBool #

Returns ``TRUE`` if the given index is not valid, and ``FALSE`` otherwise.

https://www.lua.org/manual/5.3/manual.html#lua_isnone

lua_isnoneornil :: State -> StackIndex -> IO LuaBool #

Returns ``TRUE`` if the given index is not valid or if the value at the given index is nil, and ``FALSE`` otherwise.

https://www.lua.org/manual/5.3/manual.html#lua_isnoneornil

lua_type :: State -> StackIndex -> IO TypeCode #

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

https://www.lua.org/manual/5.3/manual.html#lua_type

lua_typename #

Arguments

:: State |
-> TypeCode | tp
-> IO CString |

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

https://www.lua.org/manual/5.3/manual.html#lua_typename

lua_rawequal #

Arguments

:: State |
-> StackIndex | idx1
-> StackIndex | idx2
-> IO LuaBool |

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.

https://www.lua.org/manual/5.3/manual.html#lua_rawequal

lua_toboolean :: State -> StackIndex -> IO LuaBool #

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 ``lua_isboolean`` to test the value's type.)

https://www.lua.org/manual/5.3/manual.html#lua_toboolean

lua_tocfunction :: State -> StackIndex -> IO CFunction #

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

https://www.lua.org/manual/5.3/manual.html#lua_tocfunction

lua_tointegerx #

Arguments

:: State |
-> StackIndex | index
-> Ptr LuaBool | isnum
-> IO 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 5.3 Reference Manual); otherwise, `lua_tointegerx` returns `0`.

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

If `isnum` is not `NULL`, its referent is assigned a boolean value that indicates whether the operation succeeded.

https://www.lua.org/manual/5.3/manual.html#lua_tointegerx

lua_tonumberx #

Arguments

:: State |
-> StackIndex | index
-> Ptr LuaBool | isnum
-> IO Number |

Converts the Lua value at the given index to the C type lua_Number (see lua_Number). The Lua value must be a number or a string convertible to a number (see §3.4.3); otherwise, lua_tonumberx returns 0.

If `isnum` is not `NULL`, its referent is assigned a boolean value that indicates whether the operation succeeded.

https://www.lua.org/manual/5.3/manual.html#lua_tonumberx

lua_tolstring #

Arguments

:: State |
-> StackIndex | index
-> Ptr CSize | len
-> IO (Ptr CChar) |

Converts the Lua value at the given index to a C string. If `len` is not `NULL`, it sets the referent with the string length. The Lua value must be a string or a number; otherwise, the function returns `NULL`. If the value is a number, then `lua_tolstring` also changes the actual value in the stack to a string. (This change confuses `lua_next` when `lua_tolstring` is applied to keys during a table traversal.)

`lua_tolstring` returns a pointer to a string inside the Lua state. This string always has a zero ('0') after its last character (as in C), but can contain other zeros in its body.

Because Lua has garbage collection, there is no guarantee that the pointer returned by `lua_tolstring` will be valid after the corresponding Lua value is removed from the stack.

https://www.lua.org/manual/5.3/manual.html#lua_tolstring

lua_topointer :: State -> StackIndex -> IO (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.

https://www.lua.org/manual/5.3/manual.html#lua_topointer

lua_tothread :: State -> StackIndex -> IO 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 ``nullPtr``.

https://www.lua.org/manual/5.3/manual.html#lua_tothread

lua_touserdata :: State -> StackIndex -> IO (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 ``nullPtr``.

https://www.lua.org/manual/5.3/manual.html#lua_touserdata

lua_rawlen :: State -> StackIndex -> IO CSize #

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.

https://www.lua.org/manual/5.3/manual.html#lua_rawlen.

## Push functions (Haskell → stack)

lua_pushnil :: State -> IO () #

Pushes a nil value onto the stack.

https://www.lua.org/manual/5.3/manual.html#lua_pushnil.

lua_pushnumber :: State -> Number -> IO () #

Pushes a float with the given value onto the stack.

https://www.lua.org/manual/5.3/manual.html#lua_pushnumber.

lua_pushinteger :: State -> Integer -> IO () #

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

https://www.lua.org/manual/5.3/manual.html#lua_pushinteger.

lua_pushlstring #

Arguments

:: State |
-> Ptr CChar | s
-> CSize | len
-> IO () |

Pushes the string pointed to by `s` with size `len` 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. The string can contain any binary data, including embedded zeros.

Returns a pointer to the internal copy of the string.

https://www.lua.org/manual/5.3/manual.html#lua_pushlstring.

lua_pushstring #

Arguments

:: State |
-> CString | s
-> IO CString |

Pushes the zero-terminated 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.

Returns a pointer to the internal copy of the string.

If s is NULL, pushes nil and returns NULL.

lua_pushcclosure #

Arguments

:: State |
-> CFunction | fn
-> NumArgs | n
-> IO () |

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 lua_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. lua_pushcclosure also pops these values from the stack.

The maximum value for `n` is 255.

https://www.lua.org/manual/5.3/manual.html#lua_pushcclosure.

lua_pushcfunction #

Arguments

:: State |
-> CFunction | fn
-> IO () |

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`).

https://www.lua.org/manual/5.3/manual.html#lua_pushcfunction.

lua_pushboolean :: State -> LuaBool -> IO () #

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

https://www.lua.org/manual/5.3/manual.html#lua_pushboolean.

lua_pushlightuserdata :: State -> Ptr a -> IO () #

Pushes a light userdata onto the stack.

Userdata represent C values in Lua. A light userdata represents a pointer, a `Ptr ()` (i.e., `void*` in C lingo). 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.

https://www.lua.org/manual/5.3/manual.html#lua_pushlightuserdata.

lua_pushthread :: State -> IO CInt #

Pushes the current thread onto the stack. Returns `1` iff this thread is the main thread of its state.

https://www.lua.org/manual/5.3/manual.html#lua_pushthread.

## Get functions (Lua → stack)

lua_rawget :: State -> StackIndex -> IO TypeCode #

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

https://www.lua.org/manual/5.3/manual.html#lua_rawget.

lua_rawgeti #

Arguments

:: State |
-> StackIndex |
-> Integer | n
-> IO TypeCode |

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.

https://www.lua.org/manual/5.3/manual.html#lua_rawgeti.

lua_createtable #

Arguments

:: State |
-> CInt | narr
-> CInt | nrec
-> IO () |

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`.

https://www.lua.org/manual/5.3/manual.html#lua_createtable.

lua_newuserdata :: State -> CSize -> IO (Ptr ()) #

This function allocates a new block of memory with the given size, pushes onto the stack a new full userdata with the block address, and returns this address. The host program can freely use this memory.

https://www.lua.org/manual/5.3/manual.html#lua_newuserdata.

lua_getmetatable :: State -> StackIndex -> IO LuaBool #

If the value at the given index has a metatable, the function pushes that metatable onto the stack and returns `1`. Otherwise, the function returns `0` and pushes nothing on the stack.

https://www.lua.org/manual/5.3/manual.html#lua_getmetatable.

lua_getuservalue :: State -> StackIndex -> IO TypeCode #

Pushes onto the stack the Lua value associated with the full userdata at the given index.

Returns the type of the pushed value.

https://www.lua.org/manual/5.3/manual.html#lua_getuservalue

lua_getglobal #

Arguments

:: State |
-> CString | name
-> IO TypeCode |

Warning: This is an unsafe function, errors will lead to a program crash;consider using hslua_getglobal instead.

Pushes onto the stack the value of the global name. Returns the type of that value.

WARNING: `lua_getglobal` is unsafe in Haskell: if the call to a metamethod triggers an error, then that error cannot be handled and will lead to an unrecoverable program crash. Consider using the ``hslua_getglobal`` ersatz function instead. Likewise, the metamethod may not call a Haskell function unless the library was compiled without `allow-unsafe-gc`.

https://www.lua.org/manual/5.3/manual.html#lua_getglobal.

lua_gettable #

Arguments

:: State |
-> StackIndex | index
-> IO TypeCode |

Warning: This is an unsafe function, errors will lead to a program crash;consider using hslua_gettable instead.

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).

Returns the type of the pushed value.

WARNING: `lua_gettable` is unsafe in Haskell: if the call to a metamethod triggers an error, then that error cannot be handled and will lead to an unrecoverable program crash. Consider using the ``hslua_gettable`` ersatz function instead. Likewise, the metamethod may not call a Haskell function unless the library was compiled without `allow-unsafe-gc`.

https://www.lua.org/manual/5.3/manual.html#lua_gettable.

## Set functions (stack → Lua)

lua_rawset :: State -> StackIndex -> IO () #

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

https://www.lua.org/manual/5.3/manual.html#lua_rawset.

lua_rawseti :: State -> StackIndex -> Integer -> IO () #

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.

https://www.lua.org/manual/5.3/manual.html#lua_rawseti.

lua_setmetatable :: State -> StackIndex -> IO () #

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

https://www.lua.org/manual/5.3/manual.html#lua_setmetatable.

lua_setuservalue :: State -> StackIndex -> IO () #

Pops a value from the stack and sets it as the new value associated to the full userdata at the given index.

https://www.lua.org/manual/5.3/manual.html#lua_setuservalue

lua_setglobal #

Arguments

:: State |
-> CString | name
-> IO () |

Warning: This is an unsafe function, errors will lead to a program crash;consider using hslua_getglobal instead.

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

WARNING: `lua_setglobal` is unsafe in Haskell: if the call to a metamethod triggers an error, then that error cannot be handled and will lead to an unrecoverable program crash. Consider using the ``hslua_setglobal`` ersatz function instead. Likewise, the global metamethod may not call a Haskell function unless the library was compiled without `allow-unsafe-gc`.

https://www.lua.org/manual/5.3/manual.html#lua_setglobal.

lua_settable #

Arguments

:: State |
-> StackIndex | index
-> IO () |

Warning: This is an unsafe function, errors will lead to a program crash;consider using hslua_settable instead.

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).

WARNING: `lua_settable` is unsafe in Haskell: if the call to a metamethod triggers an error, then that error cannot be handled and will lead to an unrecoverable program crash. Consider using the ``hslua_settable`` ersatz function instead. Likewise, the metamethod may not call a Haskell function unless the library was compiled without `allow-unsafe-gc`.

https://www.lua.org/manual/5.3/manual.html#lua_settable

## Misc (safe)

lua_stringtonumber :: State -> CString -> IO CSize #

Converts the zero-terminated string `s` to a number, pushes that number into the stack, and returns the total size of the string, that is, its length plus one. The conversion can result in an integer or a float, according to the lexical conventions of Lua (see §3.1). The string may have leading and trailing spaces and a sign. If the string is not a valid numeral, returns 0 and pushes nothing. (Note that the result can be used as a boolean, true if the conversion succeeds.)

https://www.lua.org/manual/5.3/manual.html#lua_stringtonumber.

## Misc (unsafe)

lua_arith #

Arguments

:: State |
-> ArithOPCode | op
-> IO () |

Warning: This is an unsafe function, errors will lead to a program crash;consider using hslua_arith instead.

Performs an arithmetic or bitwise operation over the two values (or one, in the case of negations) at the top of the stack, with the value at the top being the second operand, pops these values, and pushes the result of the operation. The function follows the semantics of the corresponding Lua operator (that is, it may call metamethods).

The value of `op` must be one of the following constants:

- `LUA_OPADD`: performs addition (`+`)
- `LUA_OPSUB`: performs subtraction (`-`)
- `LUA_OPMUL`: performs multiplication (`*`)
- `LUA_OPDIV`: performs float division (`/`)
- `LUA_OPIDIV`: performs floor division (`//`)
- `LUA_OPMOD`: performs modulo (`%`)
- `LUA_OPPOW`: performs exponentiation (`^`)
- `LUA_OPUNM`: performs mathematical negation (unary `-`)
- `LUA_OPBNOT`: performs bitwise NOT (`~`)
- `LUA_OPBAND`: performs bitwise AND (`&`)
- `LUA_OPBOR`: performs bitwise OR (`|`)
- `LUA_OPBXOR`: performs bitwise exclusive OR (`~`)
- `LUA_OPSHL`: performs left shift (`<<`)
- `LUA_OPSHR`: performs right shift (`>>`)

WARNING: `lua_arith` is unsafe in Haskell: if the call to a metamethod triggers an error, then that error cannot be handled and will lead to an unrecoverable program crash. Consider using the ``hslua_arith`` ersatz function instead. Likewise, the metamethod may not call a Haskell function unless the library was compiled without `allow-unsafe-gc`.

https://www.lua.org/manual/5.3/manual.html#lua_arith.

lua_concat #

Arguments

:: State |
-> CInt | n
-> IO () |

Warning: This is an unsafe function, it will cause a program crash ifa metamethod throws an error.Consider using hslua_concat instead.

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).

WARNING: `lua_concat` is unsafe in Haskell: This function will cause an unrecoverable crash an error if any of the concatenated values causes an error when executing a metamethod. Consider using the ``hslua_concat`` ersatz function instead.

lua_next #

Arguments

:: State |
-> StackIndex | index
-> IO LuaBool |

Warning: This is an unsafe function, it will cause a program crash ifthe given key is neither nil nor present in the table.Consider using hslua_next instead.

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 lua_next returns `FALSE` (and pushes nothing).

A typical traversal looks like this:

    -- table is in the stack at index 't'
    lua_pushnil l    -- first key
    let loop = lua_next l t >>= \case
          FALSE -> return ()
          _ -> do
            lua_type l (-2) >>= lua_typename l >>= peekCString >>= putStrLn
            lua_type l (-1) >>= lua_typename l >>= peekCString >>= putStrLn
            -- removes 'value'; keeps 'key' for next iteration
            lua_pop l 1
            loop
    loop

While traversing a table, do not call `lua_tolstring` directly on a key, unless you know that the key is actually a string. Recall that `lua_tolstring` may change the value at the given index; this confuses the next call to lua_next.

See function next for the caveats of modifying the table during its traversal.

WARNING: `lua_next` is unsafe in Haskell: This function will cause an unrecoverable crash an error if the given key is neither `nil` nor present in the table. Consider using the ``hslua_next`` ersatz function instead.

## Load and run Lua code

lua_pcall #

Arguments

:: State |
-> NumArgs | nargs
-> NumResults | nresults
-> StackIndex | msgh
-> IO StatusCode |

Calls a function in protected mode.

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 `lua_pcall`; `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 ``LUA_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.

If there is any error, `lua_pcall` catches it, pushes a single value on the stack (the error message), and returns the error code. `lua_pcall` always removes the function and its arguments from the stack.

If `msgh` is `0`, then the error object returned on the stack is exactly the original error object. Otherwise, `msgh` 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 ``lua_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 ``lua_pcall``, since by then the stack has unwound.

https://www.lua.org/manual/5.3/manual.html#lua_pcall.

lua_load #

Arguments

:: State |
-> Reader | reader
-> Ptr () | data
-> CString | chunkname
-> CString | mode
-> IO StatusCode |

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

The return values of `lua_load` are:

- ``LUA_OK``: no errors;
- ``LUA_ERRSYNTAX``: syntax error during pre-compilation;
- ``LUA_ERRMEM``: memory allocation error;
- ``LUA_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.

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

The `lua_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 §4.9).

`lua_load` automatically detects whether the chunk is text or binary and loads it accordingly (see program `luac`). The string mode works as in function `load`, with the addition that a `NULL` value is equivalent to the string "bt".

`lua_load` uses the stack internally, so the reader function must always leave the stack unmodified when returning.

https://www.lua.org/manual/5.3/manual.html#lua_load.

## Coroutine functions

lua_status :: State -> IO StatusCode #

Returns the status of this Lua thread.

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

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

https://www.lua.org/manual/5.3/manual.html#lua_status.

## Garbage-collection

lua_gc #

Arguments

:: State |
-> GCCode | what
-> CInt | data
-> IO CInt |

Controls the garbage collector.

See the Lua docs at https://www.lua.org/manual/5.3/manual.html#lua_gc.

newtype GCCode #

Garbage-collection options.

Constructors

GCCode CInt |

#### Instances

Instances details

Eq GCCode # |
Instance details Defined in Lua.Types Methods (==) :: GCCode -> GCCode -> Bool # (/=) :: GCCode -> GCCode -> Bool #
Show GCCode # |
Instance details Defined in Lua.Types Methods showsPrec :: Int -> GCCode -> ShowS # show :: GCCode -> String # showList :: [GCCode] -> ShowS #
Storable GCCode # |
Instance details Defined in Lua.Types Methods sizeOf :: GCCode -> Int # alignment :: GCCode -> Int # peekElemOff :: Ptr GCCode -> Int -> IO GCCode # pokeElemOff :: Ptr GCCode -> Int -> GCCode -> IO () # peekByteOff :: Ptr b -> Int -> IO GCCode # pokeByteOff :: Ptr b -> Int -> GCCode -> IO () # peek :: Ptr GCCode -> IO GCCode # poke :: Ptr GCCode -> GCCode -> IO () #

pattern LUA_GCSTOP :: GCCode #

Stops the garbage collector.

pattern LUA_GCRESTART :: GCCode #

Restarts the garbage collector.

pattern LUA_GCCOLLECT :: GCCode #

Performs a full garbage-collection cycle.

pattern LUA_GCCOUNT :: GCCode #

Returns the current amount of memory (in Kbytes) in use by Lua.

pattern LUA_GCCOUNTB :: GCCode #

Returns the remainder of dividing the current amount of bytes of memory in use by Lua by 1024.

pattern LUA_GCSTEP :: GCCode #

Performs an incremental step of garbage collection.

pattern LUA_GCSETPAUSE :: GCCode #

Sets data as the new value for the pause of the collector (see §2.5) and returns the previous value of the pause.

pattern LUA_GCSETSTEPMUL :: GCCode #

Sets data as the new value for the step multiplier of the collector (see §2.5) and returns the previous value of the step multiplier.

pattern LUA_GCISRUNNING :: GCCode #

Returns a boolean that tells whether the collector is running (i.e., not stopped).

## Miscellaneous functions

lua_pushglobaltable :: State -> IO () #

Pushes the global environment onto the stack.

https://www.lua.org/manual/5.3/manual.html#lua_pushglobaltable

# The Auxiliary Library

luaL_getmetafield #

Arguments

:: State |
-> StackIndex | obj
-> CString | e
-> IO TypeCode |

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 ``LUA_TNIL``.

luaL_getmetatable :: State -> CString -> IO TypeCode #

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

luaL_loadbuffer #

Arguments

:: State |
-> Ptr CChar | buff
-> CSize | sz
-> CString | name
-> IO StatusCode |

Loads a buffer as a Lua chunk. This function uses `lua_load` to load the chunk in the buffer pointed to by `buff` with size `sz`.

This function returns the same results as `lua_load`. `name` is the chunk name, used for debug information and error messages.

luaL_openlibs :: State -> IO () #

Opens all standard Lua libraries into the given state.

https://www.lua.org/manual/5.3/manual.html#luaL_openlibs

luaL_newmetatable #

Arguments

:: State |
-> CString | tname
-> IO LuaBool |

If the registry already has the key `tname`, returns `0`. 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 `1`. (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.

luaL_ref #

Arguments

:: State |
-> StackIndex | t
-> IO CInt |

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`, `luaL_ref` ensures the uniqueness of the key it returns. You can retrieve an object referred by reference `r` by calling `lua_rawgeti l t r`. Function ``luaL_unref`` frees a reference and its associated object.

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

luaL_testudata #

Arguments

:: State | l
-> StackIndex | arg
-> CString | tname
-> IO (Ptr ()) |

Checks whether the function argument `arg` is a userdata of the type `tname` (see ``luaL_newmetatable``) and returns the userdata address (see ``lua_touserdata``). Returns `NULL` if the test fails.

https://www.lua.org/manual/5.3/manual.html#luaL_testudata

luaL_traceback #

Arguments

:: State | l
-> State | l1
-> CString | msg
-> CInt | level
-> IO () |

Creates and pushes a traceback of the stack `l1`. If `msg` is not `NULL` it is appended at the beginning of the traceback. The level parameter tells at which level to start the traceback.

luaL_unref #

Arguments

:: State |
-> StackIndex | t
-> CInt | ref
-> IO () |

Releases reference `ref` from the table at index `t` (see ``luaL_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.

## Registry fields

loadedTableRegistryField :: String #

Key, in the registry, for table of loaded modules.

preloadTableRegistryField :: String #

Key, in the registry, for table of preloaded loaders.

## 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

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

pattern LUA_REFNIL :: CInt #

Value signaling that no reference was created.

pattern LUA_NOREF :: CInt #

Value signaling that no reference was found.

fromReference :: Reference -> CInt #

Convert a reference to its C representation.

toReference :: CInt -> Reference #

Create a reference from its C representation.

# Ersatz functions

hsluaL_newstate :: IO State #

Creates a new Lua state and set extra registry values for error bookkeeping.

hsluaL_tolstring :: State -> StackIndex -> Ptr CSize -> IO (Ptr CChar) #

Converts object to string, respecting any metamethods; returns `NULL` if an error occurs.

hsluaL_requiref #

Arguments

:: State |
-> Ptr CChar | modname
-> CFunction | openf
-> LuaBool | glb
-> Ptr StatusCode |
-> IO () |

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.

## Get functions (Lua → stack)

hslua_gettable :: State -> StackIndex -> Ptr StatusCode -> IO TypeCode #

Behaves like ``lua_gettable``, but prevents unrecoverable program crashes by calling that function through ``lua_pcall``. Takes an additional status code pointer that is set to the status returned by `lua_pcall`.

hslua_getglobal :: State -> CString -> CSize -> Ptr StatusCode -> IO TypeCode #

Behaves like ``lua_getglobal``, but prevents unrecoverable program crashes by calling that function through ``lua_pcall``. Takes an additional status code pointer that is set to the status returned by `lua_pcall`.

## Set functions (stack → Lua)

hslua_settable :: State -> StackIndex -> Ptr StatusCode -> IO () #

Behaves like ``lua_settable``, but prevents unrecoverable program crashes by calling that function through ``lua_pcall``. Takes an additional status code pointer that is set to the status returned by `lua_pcall`.

hslua_setglobal :: State -> CString -> CSize -> Ptr StatusCode -> IO () #

Behaves like ``lua_setglobal``, but prevents unrecoverable program crashes by calling that function through ``lua_pcall``. Takes an additional status code pointer that is set to the status returned by `lua_pcall`.

## Misc

hslua_error :: State -> IO NumResults #

Replacement for lua_error; it uses the HsLua error signaling convention instead of raw Lua errors.

hslua_next :: State -> StackIndex -> Ptr StatusCode -> IO LuaBool #

Wrapper around lua_next which catches any Lua errors.

hslua_concat :: State -> NumArgs -> Ptr StatusCode -> IO () #

Wrapper around lua_concat which catches any Lua errors.

hslua_arith #

Arguments

:: State |
-> ArithOPCode | op
-> Ptr StatusCode |
-> IO () |

Performs an arithmetic or bitwise operation over the two values (or one, in the case of negations) at the top of the stack, with the value at the top being the second operand, pops these values, and pushes the result of the operation. The function follows the semantics of the corresponding Lua operator (that is, it may call metamethods).

The value of `op` must be one of the following constants:

- `LUA_OPADD`: performs addition (`+`)
- `LUA_OPSUB`: performs subtraction (`-`)
- `LUA_OPMUL`: performs multiplication (`*`)
- `LUA_OPDIV`: performs float division (`/`)
- `LUA_OPIDIV`: performs floor division (`//`)
- `LUA_OPMOD`: performs modulo (`%`)
- `LUA_OPPOW`: performs exponentiation (`^`)
- `LUA_OPUNM`: performs mathematical negation (unary `-`)
- `LUA_OPBNOT`: performs bitwise NOT (`~`)
- `LUA_OPBAND`: performs bitwise AND (`&`)
- `LUA_OPBOR`: performs bitwise OR (`|`)
- `LUA_OPBXOR`: performs bitwise exclusive OR (`~`)
- `LUA_OPSHL`: performs left shift (`<<`)
- `LUA_OPSHR`: performs right shift (`>>`)

This function wraps `lua_arith` and takes an additional parameter `status`; if it is not `NULL`, then the return value is set to the status after calling `lua_arith`.

hslua_compare #

Arguments

:: State |
-> StackIndex | index 1
-> StackIndex | index 2
-> OPCode | operator
-> Ptr StatusCode | status
-> IO LuaBool |

Compares two Lua values. Returns `1` if the value at index `index1` satisfies op when compared with the value at index `index2`, following the semantics of the corresponding Lua operator (that is, it may call metamethods). Otherwise returns `0`. Also returns `0` if any of the indices is not valid.

The value of op must be one of the following constants:

- `LUA_OPEQ`: compares for equality (==)
- `LUA_OPLT`: compares for less than (<)
- `LUA_OPLE`: compares for less or equal (<=)

This function wraps `lua_compare` and takes an additional parameter `status`; if it is not `NULL`, then the return value is set to the status after calling `lua_compare`.

# Standard Lua libraries

luaopen_base :: CFunction #

Pointer to function opening the base library.

luaopen_table :: CFunction #

Pointer to function opening the table library.

luaopen_io :: CFunction #

Pointer to function opening the io library.

luaopen_os :: CFunction #

Pointer to function opening the os library.

luaopen_string :: CFunction #

Pointer to function opening the string library.

luaopen_math :: CFunction #

Pointer to function opening the math library.

luaopen_debug :: CFunction #

Pointer to function opening the debug library.

luaopen_package :: CFunction #

Pointer to function opening the package library.

# Push Haskell functions

hslua_pushhsfunction :: State -> PreCFunction -> IO () #

Pushes a Haskell operation as a Lua function. The Haskell operation is expected to follow the custom error protocol, i.e., it must signal errors with ``hslua_error``.

### Example

Export the function to calculate triangular numbers.

    let triangular :: PreCFunction
        triangular l' = do
          n <- lua_tointegerx l' (nthBottom 1) nullPtr
          lua_pushinteger l' (sum [1..n])
          return (NumResults 1)

    hslua_newhsfunction l triangular
    withCString "triangular" (lua_setglobal l)