[plt-scheme] V4 request for thoughts on various question

I will answer some here.

Grant Rettke wrote:
> Hi folks,
>
> While reading the V4 guide (not detailed reference, yet) I noted some
> questions, and wondered what other folks had to say about them:
>
> When do you use weak hash tables?
>   

I used weak hash once tables in v371/372 or so. It's just weak reference 
+ hash table. See Noel's reply.

> When might folks use case-lambda rather than keyword or optional arguments?
>
> Does anyone use the curried define form?
>   

I did sometimes.

> Do folks use values and define-values much, or destructure and use
> lists, match-define or match-let instead?
>   
I prefer values over destructure.

> The fact that let allow paralell bindings, do some folks take that
> fact and perform optimizations on multiple cpu boxes? Is it worth it?
>
> How would you use letrec-values?
>
>   

If one of the `val-expr' of a letrec  returns multiple values.

> I don't use structures much, but they seem pretty versatile and
> therefore important; are they?
>
>   
Yes.

> Structure guards are neat. Where does this fit in dynamic world? You
> could make a type change and detect it in a running system.  Is typing
> the data enough, is that the perfect mix between static and dynamic
> languages?
>
> Units seem much easier to understand. Is that just a documentation
> change? Are any of you going to use units more? I see a place where I
> could use units instead of classes, which I had used because units
> just didn't make sense to me.
>
>   

I think it is just documentation. If no inherit/superclass is needed, I 
won't use class.

> Best wishes,
>
> Grant
>
>   

Chongkai