[MLton] MLB file tree

[Stephen Weeks]

> I wonder, though, whether the format could be improved.  Only one of
> the '{ }' and the indenting are necessary to capture the nesting;
> the '{ }' would seem easier to handle by text processing.

Having both {} and nesting has the benefit for humans that the nesting
is both visually apparent and the output is easily navigable by
{back,for}ward-sexp.

> The fact that the mlb files aren't part of the output of "-stop f" is 
> probably not the right choice.  We usually use "-stop f" to extract 
> dependencies for a Makefile; technically, you could change a mlb file in a 
> manner that changes the meaning of a program without changing the list of 
> source .sml files.

Good point.  For example, one could reorder the files, changing the
order of side effects.

We did sometimes use -stop f to produce a list of SML files so that
one could feed the list to SML/NJ or concatenate all the code
together.  But it's easy enough grep -v out the MLBs to obtain this
behavior.  So, if people want, it seems reasonable to me to change the
meaning of -stop f to include MLB files.