_ffi syntax

[Matthew Fluet]

> This was all started when I saw Matt's use of printf.  I don't blame him, but
> it is a real sign of the clumsyness of print.  Did you ever try playing with
> Danvy's trick to see how it actually felt.  I'm not talking about efficiency,
> just convenience and readability.

Also, don't get me wrong -- I don't use printf in my ML programs; it's
just a convienent way of eliminating all of the basis-support for IO when
I'm trying to debug the backend; it's a little too easy to get lost in a
huge .cps file.