[e-lang] StaticScope's hasMetaStateExpr definition

[Mark S. Miller]

Kevin Reid wrote:
> Um. I seem to remember having discussed this already (not on the  
> mailing list) after I asked the above question.
> 
> My own proposal was that e`...` should return *unexpanded* (full E)  
> node trees, thus allowing composition to happen before any expansion.
> 
> If we do this, then only E and Kernel-E need exist.


Yes, that is reasonable and would work. There are two things that make me 
uncomfortable with this:

1) Even trivially different syntactic forms of the "same" expression, such as 
"x + y" vs "x.add(y)", would become distinct cases. OTOH, given a library of 
source-to-source transformers, one could always first apply the transformer 
that did the desired case folding. Since the programmer would then have full 
flexibility in choosing which foldings they wish, maximum flexibility does 
indeed argue for your suggestion.

2) If done in the style of the current ENode trees, it requires an explicitly 
different kind of object per syntactic form. How many is it? Does this use 
justify introducing all those kinds of objects? Perhaps a more 
S-expression-ish representation, such as a term-tree, would be more 
appropriate for this use?


-- 
Text by me above is hereby placed in the public domain

     Cheers,
     --MarkM