A Haskell wrapper library for a scripting language Lua. See http://www.lua.org/ for more details.

This module is intended to be imported qualified, eg.

 import qualified Scripting.Lua as Lua

This way we use Haskell module hierarchy to make Lua names shorter. Haskell functions are named after Lua functions, but the lua_ or luaL_ prefix.

Lua types are mapped to Haskell types as in the following table:

 int (stack index)        Int
 lua_Integer              LuaInteger
 lua_Number               LuaNumber
 int (bool result)        Bool
 const char * (string)    String
 void *                   Ptr ()
 lua_State *              LuaState

Most functions are one-to-one mappings. Rare special cases are clearly marked in this document.

Minimal sample embedding:

 import qualified Scripting.Lua as Lua

 main = do
     l <- Lua.newstate
     Lua.openlibs l
     Lua.callproc l "print" "Hello from Lua"
     Lua.close l

Call a Lua procedure. Use as:

 callproc l "proc" "abc" (1::Int) (5.0::Double)

Call a Lua function. Use as:

 Just v <- callfunc l "proc" "abc" (1::Int) (5.0::Double)

Loads a Lua script file and executes it immediatelly. Use as:

 Lua.dofile l "myscript.lua"
 Just result <- Lua.peek l (-1)

Loads a Lua script given as string parameter and executes it immediatelly | Loads a Lua script file and executes it immediatelly. Use as:

 Lua.dostring l "return 42"
 Just result <- Lua.peek l (-1)

Convert a Haskell function to Lua function. Any Haskell function can be converted provided that:

• all arguments are instances of StackValue * return type is IO t, where t is an instance of StackValue

Any Haskell exception will be converted to a string and returned as Lua error.

Like getglobal, but knows about packages. e. g.

 getglobal l "math.sin"

returns correct result

Pushes Haskell function converted to a Lua function. All values created will be garbage collected. Use as:

 Lua.pushfunction l myfun
 Lua.setglobal l "myfun"

You are not allowed to use lua_error anywhere, but use an error code of (-1) to the same effect. Push error message as the sole return value.

See lua_error in Lua Reference Manual. error :: LuaState -> IO Int error l = liftM fromIntegral (c_lua_error l)

See lua_gc in Lua Reference Manual.