[MLton] mlnlffigen is awesome (was: bootstrap problem)

[Matthew Fluet]

> Clarity is much more important than concision in MLBs, since they are
> such a small fraction of the code in a project.

Agreed.

> One remaining question in my mind is whether
> $(HOME)/.mlton/mlb-path-map should be processed by default.  On the
> minus side, it is an implicit dependence on an environment variable
> and makes it easier for package distributors to make mistakes,
> accidentally depending on personal path variables.  But, if
> distributors are aware of it perhaps that's not such a big deal.  On
> the plus side is the possibility that most users would find it
> convenient.  Since the theory is that there are many more users than
> distributors, we should favor them.  While writing a script like
> Matthew's is easy, it's kind of silly to make everyone do it.

I'm undecided.  As Henry has pointed out, once you have an implicit
dependency, it seems to make sense to be able to disable that dependency.  

> Another question is whether to allow multiple -mlb-path-map arguments?
> And if so, does it make more sense to have later definitions take
> precedence (as we have) or earlier ones?

I would expect later definitions to take precedence over earlier ones.