[MLton] can mlbasis rename the top-level?

[Stephen Weeks]

> I like the idea of delimiting the the sml in a manner that doesn't
> require embedding the SML grammar in the MLB grammar.

I can see that this is much easier from an implementation perspective,
but I wonder if you have other reasons?

> I imagine something like the above could be handled by the lexer,
> yielding a (big) string token, which could be pushed through the SML
> lexer/parser rather than a file name.

This does seem easy.  It requires that the MLB lexer handle SML
comments so that one doesn't accidentally close the SML code from
within a comment.  And it requires that we choose a closing character
sequence that could not occur in SML.  "}}}" doesn't work.  How about
"___" or "_sml"?