Re: [boost] FC++ integration/future issues (was "Some FC++ comments")

From: Brian McNamara (lorgon_at_[hidden])
Date: 2003-08-15 15:16:13

On Fri, Aug 15, 2003 at 02:44:20PM -0400, Joel Young wrote:
> From: Brian McNamara <lorgon_at_[hidden]>
> > to think deeply about it though; it is unclear to me if the FC++
> > implicit assumption of 'value semantics' (FC++ doesn't allow (mutable)
> > reference parameters) will throw a wrench in the works.  It is also
> 
> I tried using FC++ a while ago for flexibly expressing and passing
> around linear algebra pipelines and I found this lack of mutable
> reference parameters to be highly constraining and insanely frustrating.
> I wanted to be able to take a reference to a vector as a parameter and
> return that same vector, mutated, as a return value.  I started to hack
> FC++ to remove the const on the references but after a bit gave up.

Yes... square peg, round hole.  (You can use pointers, but this
sometimes turns existing code into mess of "&"s, "*"s, and
"compose(dereference)"s.)

An open question (which someone on the list suggested) is whether
monads will provide a convenient interface to bring mutation cleanly
back into the mix.  That's what happens, e.g., in Haskell.  But the
monad stuff in FC++ is really new (and monads are still pretty new to
me), so it isn't yet clear if/how this may address the issue.

-- 
-Brian McNamara (lorgon_at_[hidden])