> It seems that the infinite loop
>
>  let rec x = 1 :: x in x = x ;;
>
> cannot be interrupted by Control-C in the interactive session of
> Objective Caml 3.09.0

This is probably because of the way the interpreter is designed.

Signals are only checked after function calls, and one other operation
I can't remember off hand. Obviously, in your example, neither of
these cases occur, so ocaml doesn't get a chance to check for any
signals: hence, can't be interrupted.

Jonathan