lua_load[-0, +1, –] int lua_load (lua_State *L, lua_Reader reader, void *data, const char *chunkname, const char *mode); 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 precompilation; LUA_ERRMEM: memory allocation

os.getenv (varname) Returns the value of the process environment variable varname, or nil if the variable is not defined.

math.acos (x) Returns the arc cosine of x (in radians).

3.4.10 – Function Calls A function call in Lua has the following syntax: functioncall ::= prefixexp args In a function call, first prefixexp and args are evaluated. If the value of prefixexp has type function, then this function is called with the given arguments. Otherwise, the prefixexp "call" metamethod is called, having as first parameter the value of prefixexp, followed by the original call arguments (see §2.4). The form functioncall ::= prefixexp ‘:’ Name args can be used to call "

lua_createtable[-0, +1, m] void lua_createtable (lua_State *L, int narr, int nrec); 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

lua_getfield[-0, +1, e] int lua_getfield (lua_State *L, int index, const char *k); Pushes onto the stack the value t[k], where t is the value at the given index. As in Lua, this function may trigger a metamethod for the "index" event (see §2.4). Returns the type of the pushed value.

luaL_addsize[-?, +?, –] void luaL_addsize (luaL_Buffer *B, size_t n); Adds to the buffer B (see luaL_Buffer) a string of length n previously copied to the buffer area (see luaL_prepbuffer).

io.open (filename [, mode]) This function opens a file, in the mode specified in the string mode. In case of success, it returns a new file handle. The mode string can be any of the following: "r": read mode (the default); "w": write mode; "a": append mode; "r+": update mode, all previous data is preserved; "w+": update mode, all previous data is erased; "a+": append update mode, previous data is preserved, writing is only allowed at the end of file. The mode string can also

lua_Hook typedef void (*lua_Hook) (lua_State *L, lua_Debug *ar); Type for debugging hook functions. Whenever a hook is called, its ar argument has its field event set to the specific event that triggered the hook. Lua identifies these events with the following constants: LUA_HOOKCALL, LUA_HOOKRET, LUA_HOOKTAILCALL, LUA_HOOKLINE, and LUA_HOOKCOUNT. Moreover, for line events, the field currentline is also set. To get the value of any other field in ar, the hook must call lua_getinfo. For ca

lua_upvaluejoin[-0, +0, –] void lua_upvaluejoin (lua_State *L, int funcindex1, int n1, int funcindex2, int n2); Make the n1-th upvalue of the Lua closure at index funcindex1 refer to the n2-th upvalue of the Lua closure at index funcindex2.