[MLton] upcoming release

[Stephen Weeks]

> Another alternative might be
> 
>   nonexhaustiveExnMatch {default|ignore}
> 
> where "default" means to follow the nonexhaustiveMatch annotation.

Sounds good.

> All of the libraries in the MLton source should have "warnMatch true", and 
> the silence of compilation indicates that there are no nonexhaustive or 
> redundant matches in the sources.  We would like to preserve that in 
> future code evolution, so we would replace "warnMatch true" with 
> "nonexhaustiveMatch warn, redundantMatch warn".

With our new-found capabilities, maybe even

 "nonexhaustiveMatch warn, redundantMatch error"

or even

 "nonexhaustiveMatch error, redundantMatch error"

> I'm still in favor of skipping ignore|warn|error with regards to
> unusedIdentifier in this round.

Only to avoid release delay, right?