[MLton] mlb files

[Matthew Fluet]

> I was looking through the mlb files that we now use to build the MLton
> tools and libraries and I have to say that the mlb stuff is looking
> really good.  Having a real language for describing programming in the
> very large is a huge win.  And having a real language is also a huge
> improvement over CM, as our few examples already show.

Yes.  I particularly like mllex and mlyacc, where the "main" program is
built in the Basis Library environment but the driver is build in the
MLton Library.