Re: [Caml-list] Single-case union types as strong typedefs

["Jacques Carette" <carette@mcmaster.ca>]

Good points, which I will comment on in opposite order:

Damien Doligez <damien.doligez@inria.fr> wrote:
> On Oct 25, 2004, at 16:25, Jacques Carette wrote:
> > Yes, I am assuming that a fair bit of partial evaluation is a good 
> > thing for
> > the compiler to do.
> 
> Unfortunately, the compiler doesn't have all the information about the
> program.  A lot of things are not known until link-time.

I consider a linker to be an integral part of a compiler 'suite'.  I could not care less when a particular code 
optimization is done.  If it *has* to be done by the linker, then so be it.  I do not understand why link-time 
optimizations seem to have been somehow less research-worthy than other parts of the compiler.

> > Isn't that correct though?  The value x is completely known 
> > statically, and
> > all computation on x can be done statically, so it is not necessary to 
> > have any traces of x left at run-time.
> 
> Then how do you pass it to a polymorphic function?

And then what?  What could that polymorphic function do with that value (without using Obj)?

In a system which insists on separate compilation, there is indeed a problem, and this ideal cannot be achieved.  I 
should have been clearer about the fact that I knew this.

Personally, I do not use separate compilation at "production" time anymore, only at development/debugging time.  When 
it comes time to produce a final executable, I use a colleague's script to make one (large) .ml file containing the 
complete program.  I'd love to have a compiler switch to tell the compiler I am producing an executable in one pass 
versus creating a reusable library.  The intentional differences between those two activities are huge, and apparently 
still under-recognized (and thus under-used).  This is surprising.

Side note: Ocaml (and Haskell) are the two languages I actively choose to code in, and get my students to code in, 
after having coded in a whole bunch of languages (professionally and otherwise).  When I need efficiency or 
non-trivial I/O, I chose Ocaml, if I only need elegance and brevity, I choose Haskell.  I still hack in Maple because 
I can prototype things there faster than in most other languages (for my own work).  But I am keeping up with Focal 
(ex-FOC) and Epigram, as they both seem to be going where I'd like my programming languages to be.  Of course, I would 
rather use fewer languages!  So I see it as worth my while to see Ocaml evolve.

Jacques