[MLton] Building MLton

[Stephen Weeks]

> But... I think this whole discussion misses the point that the MLton
> compiler does it's own data layout. It doesn't use C's types except at
> interface boundaries. So, using a portable C type is not helpful.

Using a portable C type will improve the runtime code, which is
written in C.

> The problem of 64-bit for MLton is one of teaching the compiler to
> pack bigger pointers, and the runtime to interact properly with it.

This summarizes the situation nicely.  No amount of C hacking will fix
the problem.  A fair bit of (SML) compiler hacking is required.