My answer is the same:
1. things cannot be written in Lua.
2. things are easier to write in C.
for example:
You've got a C++ game as the host program of lua, and you want to move
the player character from axis (1,1) to (999,999), without providing
the C++ function in Lua, you cannot do this at all.
You're the author of awesome window manager,
a window manager is undoubtly an application, and it provides features
such as window decorations and window movement, maximize, minimize,
size, zoom. and it also captures keyboard/mouse input in order to
provide shoutcuts. See http://awesome.naquadah.org/doc/api/ to check
what he had done, all those are written in C, because those has to
written in C in order that Lua can access those features.
You're a developer of a MID device, you want to access certain
features such as WiFi signal check, Bluetooth switch, LED screen
brightness, you will have to write those in C.
If that is a bit hardware-related, just think: you want to "minimize
every applications and show the desktop." Can you do that in Lua?
There's so many things cannot be done in Lua, so we must write those
in C, and provide functions in Lua.
