Lua.Ersatz

Ersatz functions for Lua API items which may, directly or indirectly, throw a Lua error.

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_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.

Auxiliary Library

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.