At work, I use Lua and LPeg [1] to process SIP messages. It was easy to embed, the coroutine support makes writing an event driven daemon easy (the Lua code is

At work, I use Lua and LPeg [1] to process SIP messages. It was easy to embed, the coroutine support makes writing an event driven daemon easy (the Lua code is imperative despite being event driven) and LPeg makes parsing text super easy. It's also proven "fast enough" that no real attempt at optimization has been done. [1] Lua Parser Expression Grammar