remake from source fails?

[Stephen Weeks]

> You can not build the new version of MLton with a much older one because of the
> library changes (although see below).

I was wrong about this, and was just reminded of an easy way to do it, provided
that the compiler primitives (_prim's) have not changed.  You can use the old
MLton executable and the new basis library implementation to create an old MLton
that knows about the new basis.

To to this with my sources, I execute the following command in my lib dir.

./mlton ../src/basis-library/ world

Now, this old version of mlton should be capable of compiling the new one.