can't make symbol keyed hash table

[Ken Dickey]

Ikarus Scheme version 0.0.2patched+ (revision 1330, build 2008-01-05)
Copyright (c) 2006-2007 Abdulaziz Ghuloum

> (import (rnrs hashtables (6)))
> (define st (make-hashtable symbol-hash eq?))
Unhandled exception
 Condition components:
   1. &error
   2. &who: ikarus
   3. &message: "primitive not supported yet"
   4. &message: "please file a bug report to help us prioritize our goals"
   5. &url: "https://bugs.launchpad.net/ikarus/+filebug"
   6. &irritants: (make-hashtable)
>

[Abdulaziz Ghuloum (aghuloum)]

Just a question: Is there a reason why make-eq-hashtable doesn't fit
the bill?

It seems to be doing at least the same thing you wanted, given that
the comparison predicate you want to use is eq.

[Ken Dickey (ken-dickey)]

On Tuesday 08 January 2008 02:33:23 pm Abdulaziz Ghuloum wrote:
> Just a question: Is there a reason why make-eq-hashtable doesn't fit
> the bill?

I wanted to limit the keys be symbols.

I did switch now using an eq-hashtable.

This is not a show-stopper for me, I can use a cover-function. I just did
what the error diagnostic suggested was good citizenship.

Cheers,
-KenD

BTW: THANKS VERY MUCH FOR IKARUS!! I am having much fun learning the
language called "R6RS Scheme". ;^)

[Abdulaziz Ghuloum (aghuloum)]

On Jan 8, 2008, at 6:16 PM, Ken Dickey wrote:

> This is not a show-stopper for me, I can use a cover-function. I
> just did
> what the error diagnostic suggested was good citizenship.

Thanks. I'll mark this as a low priority for now since, as you said,
it's not a show-stopper. I'll bump it if more people need it.

> BTW: THANKS VERY MUCH FOR IKARUS!! I am having much fun learning the
> language called "R6RS Scheme". ;^)

Glad to be of service :-)

[leppie (leppie)]

Unhandled exception
 Condition components:
   1. &error
   2. &who: ikarus
   3. &message: "primitive not supported yet"
   4. &message: "please file a bug report to help us prioritize our goals"
   5. &url: "https://bugs.launchpad.net/ikarus/+filebug"
   6. &irritants: (make-eqv-hashtable)

Was not sure if I should create a new report.

Cheers

leppie

[Abdulaziz Ghuloum (aghuloum)]

It's fine here. Question to help me out: what are you using make-eqv-hashtable for? (I have only found eq hash tables useful, so, I'm interested in knowing what people use eqv hash tables for)

[leppie (leppie)]

I use chars or numbers for keys in my case. Specifically this group-by function:

; returns a list of grouping
(define (group-by sel proc lst)
  (let ((ht (make-eqv-hashtable)))
    (for-each
      (lambda (x)
        (let ((key (proc x)))
          (hashtable-update! ht key
            (lambda (o)
              (cons (sel x) o))
            '())))
      lst)
    (vector->list
      (vector-map
        (lambda (key)
          (make-grouping key (hashtable-ref ht key '())))
        (hashtable-keys ht)))))

[leppie (leppie)]

I am not so sure about strings though. I might need to fall back to make-hashtable.

[Abdulaziz Ghuloum (aghuloum)]

On Apr 20, 2008, at 2:57 PM, leppie wrote:
> I am not so sure about strings though. I might need to fall back to
> make-hashtable.

Which I also don't have. :-)

[leppie (leppie)]

Hmmm, I just did the following:

Ikarus Scheme version 0.0.3+ (revision 1452, build 2008-04-20)
Copyright (c) 2006-2008 Abdulaziz Ghuloum

> (define ht (make-eq-hashtable))

> (hashtable-set! ht 1 'one)

> (hashtable-set! ht 2 'two)

> (hashtable-set! ht 1 'oneone)

> (hashtable-keys ht)
#(1 2)

> (hashtable-set! ht #\c 'two)

> (hashtable-set! ht "hello" 'two)

> (hashtable-keys ht)
#(1 2 #\c "hello")

> (hashtable-set! ht "hello" 'twotwo)

> (hashtable-set! ht #\c 'twof)

> (hashtable-keys ht)
#(1 2 #\c "hello" "hello")

It appears your eq-hashtable is closer to eqv, in fact on IronScheme I dont make that distinction either :)

[leppie (leppie)]

I still dont understand this craziness between eq? and eqv? and all the implementation-dependent behaviour that makes them distinct. IMO the distinction should be much clearer.

Anyways, make-eq-hashtable and make-eqv-hashtable should probably be one and the same thing on Ikarus (as it behaves like I expect an eqv-hashtable to behave).

Cheers

leppie

[Abdulaziz Ghuloum (aghuloum)]

On Apr 23, 2008, at 11:48 AM, leppie wrote:
> I still dont understand this craziness between eq? and eqv? and all
> the
> implementation-dependent behaviour that makes them distinct. IMO the
> distinction should be much clearer.
>
> Anyways, make-eq-hashtable and make-eqv-hashtable should probably
> be one
> and the same thing on Ikarus (as it behaves like I expect an eqv-
> hashtable to behave).

In Ikarus, they would only differ in non-fixnum numbers (bignums,
ratnums,
flonums, etc.) where eq? and eqv? differ. For everything else, they
behave the same. That's why I did not feel it was so urgent to add them
to Ikarus.

[Ramana Kumar (xrchz)]

I would like to be able to use make-hashtable and equal-hash to use a hashtable for memoizing a function (the key would be the argument list). Unfortunately it seems make-hashtable is not yet implemented - so here's a request. (Or suggestions for a better key for memoization? I mean I could use a different non-structured key for each individual function, but what about in general?)

[Ramana Kumar (xrchz)]

I would also like hashtables for other things... so this is a request to increase the priority of the implementation of make-hashtable.

[Abdulaziz Ghuloum (aghuloum)]

Added in rev 1642.

[Ramana Kumar (xrchz)]

what did you add?
Ikarus Scheme version 0.0.3+ (revision 1691, build 2008-11-23)
Copyright (c) 2006-2008 Abdulaziz Ghuloum

> (equal-hash)
Unhandled exception
 Condition components:
   1. &error
   2. &who: ikarus
   3. &message: "primitive not supported yet"
   4. &message: "please file a bug report to help us prioritize our goals"
   5. &url: "https://bugs.launchpad.net/ikarus/+filebug"
   6. &irritants: (equal-hash)

[Ramana Kumar (xrchz)]

I would like equal-hash =)

[Abdulaziz Ghuloum (aghuloum)]

Sorry, the original bug report was about make-hashtable and symbol-hash, which were implemented in addition to string-hash, string-ci-hash, and make-eqv-hashtable.

There was some discussion recently about equal-hash in
  http://groups.google.com/group/ikarus-users/msg/fc35e1a7403162f4

Please do read that subthread and let me know if there's something I missed.

Aziz,,,

[Abdulaziz Ghuloum (aghuloum)]

On Nov 27, 2008, at 11:52 AM, Ramana Kumar wrote:

> I would like equal-hash =)

BTW, you might want to experiment with "hash-consing" your
data structures and using eq-hashtables for memoization.
Just an idea. You probably want to check with Dan to see
what he has to say.

Aziz,,,