In Phalcon 2 why are there .zep, .zep.c files in the ext directory?

I'm now using Phalcon 2 and being able to read the source is very helpful. I just found myself accidentally in ext directory instead of phalcon and there were .zep.c and .zep.h files there and I was confused for a moment. I'm wondering what the current state of Zephir and Phalcon are and if complicated extensions still need to use the C language for some things.

.zep.c and .zep.h are the C code generated by Zephir which has to be compiled by a regular C compiler