Re: [Chicken-users] functions for hash tables

[felix winkelmann]

On Thu, 27 Jan 2005 21:48:08 +0100 (CET),
address@hidden <address@hidden>
wrote:
> On 27 Jan 2005, felix winkelmann <address@hidden> wrote:
> > > 1.
> > > hash-table-update! is missing (although important).
> >
> > If I understand this correctly, it's hash-table-set! with an update 
> > function,
> > right?
> 
> Yes.
> 
> > Is this really that useful?
> 
> Without such a function, each modification of a hash table's value would
> require two calls:
> 
>   hash-table-ref
> AND
>   hash-table-set!
> (which calculates the hash for the key twice,
> some more complications if the key is not in the hash table).

Ah, now I understand. Consider this implemented.

> 
> > > 3.
> > > hash-table-ref is called hash-table-get in all other implementations.
> >
> > Hm, I prefer -ref and -set!.
> 
> Ok. I see that many people want Chicken to be avantgard :-) Why not?
> But there is a small asymmetry:
> -ref and -set! work with numerical "keys" whose values  _always exist_ in
> the given list/string/vector (otherwise an error would be triggered) -
> while -put! might legally create a new key-value pair
> and -get returns for a nonexisting key _without_ an error.

One could just as well consider a hash-table to be a vector with an
unbounded number of elements...

Anyway, I'm not going into deep philosophical discussions about this.
-ref and -set! is what I'm used to in Scheme, when fetching/storing something
in a data structure.


cheers,
felix