[R6RS] Re: Why there are two syntactic layers

[Anton van Straaten]

William D Clinger wrote:
> I'm generally with Mike on this, but I have a befuddled feeling
> about the argument.  Layering is good, isn't it?  It is especially
> good when the fancy layers can be banished to modules, so those
> who don't want to learn or use the fancy layers don't have to,
> and those who do want to can.
> 
> So what's the fuss about?

The "featureful syntactic layer" doesn't seem to provide many more 
features than than the simple layer.  It's just three shortcut syntaxes 
and an initialization option.  Does it really warrant existence as a 
separate library module, in the standard?

It's true that the featureful layer can be explained in terms of the 
simple layer, but I don't see that this alone warrants such an explicit 
separation.

Implementation of the fancy layer doesn't seem to be a particular burden 
on implementors, either.  If the main reason for separating it out is a 
philosophical objection to the features it offers, I think we should 
seriously consider combining the two layers.  Those with a philosophical 
objection to the shortcut syntaxes don't have to use them, even if they 
aren't in a separate module.

> so those who don't want to learn or use the fancy layers don't
> have to, and those who do want to can.

This highlights my point: if learning the fancy layer was much of a 
barrier, I'd see more point in it being a separate layer.  However, 
learning this particular fancy layer mainly involves recognizing that 
you can leave out some bits if you like.

I'm not as strongly opposed to the separation as Marc, but if we were 
adopting that proposal, I'd rather see either a single syntactic layer, 
or a more featureful fancy layer which would better justify its 
independent existence.

Anton