How to send output to another terminal?

[Karel Miklav]

I'm playing with functional languages and I'd like to send text 
selections from vim to another xterm running language interpreter. 
Echoing from one terminal to another via /dev/tty* gets the message 
through, but it's invisible to the interpreter.

Could you please give me some hints as to what knowledge do I miss to 
make it happen and if I'm on the right track at all?

-- 

Regards,
Karel Miklav