Erlang itself is written in Erlang. Sounds strange? Yes, because it is only partially true. OK look at it in more detail:
- Erlang preprocessor is written in Erlang.
- Erlang parser is written in Erlang.
- Erlang compiler to BEAM (byte-code VM) is written in Erlang.
- Erlang compiler to HiPE (native VM extension) is written in Erlang.
- Erlang VM BEAM and HiPE is written mostly in C.
- Linked-in drivers are written mostly in C. (They are plugged to VM and serves communication with outside world.)
- OTP is written in Erlang.
- Another ports or nodes can be written in any language.