Rational sequence

[Alastair Reid]

>> Does this mean that we can safely enable USE_DOUBLE_PRECISION now?

btw configure.in says:
  
  dnl Disabled for now because the plugin-code can't handle the change.
  dnl If you're not using plugins, you could turn this on manually
  dnl by setting "USE_DOUBLE_PRECISION" in options.h.in (before running
  dnl the configure script).
  dnl AC_ARG_ENABLE(double-precision, [  --enable-double-precision use double precision arithmetic],  AC_DEFINE(USE_DOUBLE_PRECISION))
  
I don't remember exactly what I meant by this comment but plugins is
the word we used to describe dynamically linked code.

One kind of dynamically linked code was primitive declarations (see
src/plugin.c).  This later grew into GreenCard1, GreenCard2 and, now,
the foreign function interface.  The foreign function interface code
has all been rewritten and improved a lot since it was first written
so it should be cool.

I think we also used 'plugin' to refer to use of Hugs to write
'plugins' for things like web browsers via the Hugs_Server interface
(src/server.c). AFAIK, that code hasn't received the attention that
the ffi has received so I'm less confident that it can cope smoothly
with a switch.  (But others have hacked on that code more recently
than I - perhaps with the intention of removing broken assumptions.)

I'm not saying that either has problems - just indicating areas where
we need to check that the testsuite is thorough enough to catch any
problems that might be there.

--
Alastair