[MLton] compiler dependencies

[Stephen Weeks]

> I am surmising from your comments that your focus is very, very far away
> from Windows development.

Correct, in that we haven't spent the time to port MLton to Windows
native.  User have expressed interest, however, in both Windows native
and MinGW ports.  We would welcome such a port.

> If you become interested in Windows, be advised that Cygwin has
> licensing issues which make it unacceptable for most commercial use.
> Its library functionality is contained in a GPL'd .dll, which if used,
> would put all of one's commercial software under the GPL.

We are aware of the licensing issues with Cygwin, as we have supported
our Cygwin port for over two years.  If you want to use Cygwin in a
commercial environment, another option besides GPLing your application
is to pay RedHat a licensing fee.  I don't know the fee structure, so
I don't know in what situations this could be made to work.

> MinGW is the effort to use native Windows .dlls and avoid all licensing
> issues, while still providing a UNIX environment.

Yep, it sounds good.  When we initially added support for Cygwin about
2 1/2 years ago, MinGW's license was attractive, but the code was too
embryonic to use.  I imagine it would be fine today.

> My rule of thumb is that if a project does not have a VC++ build, they
> aren't serious about Windows development.  Such projects typically have
> zero people actually compiling, testing, and using things on Windows.
...
> VC++ is of course standard industry practice.

Good to know.  I'm still a bit confused (remember, I know *nothing*
about VC++) about what it means to "have a VC++ build" of MLton.  Do
you mean that MLton's runtime can be compiled with VC++, or that MLton
can use VC++ when it needs to call a C compiler, or that MLton can use
the assembler that I assume comes with VC++, or some combination of
these, or something else?