Re: [Chicken-users] hash-table-update!/default is broken

[felix winkelmann]

Thanks, Thomas. Patch is applied.


cheers,
felix

On 2/21/06, Thomas Chust <address@hidden> wrote:
> Hello,
>
> the function hash-table-update!/default and also hash-table-update! on
> which it is based in CHICKEN do not behave as prescribed by SRFI-69:
>
> > $ csi
> >   @@@@@@@ @@@  @@@ @@@  @@@@@@@ @@@  @@@ @@@@@@@@ @@@  @@@
> >  !@@      @@!  @@@ @@! !@@      @@!  !@@ @@!      @@address@hidden@@@
> >  address@hidden      @address@hidden@address@hidden !!@ address@hidden      
> > @!@@address@hidden  @!!!:!   @!@@address@hidden
> >  :!!      !!:  !!! !!: :!!      !!: :!!  !!:      !!:  !!!
> >   :: :: :  :   : : :    :: :: :  :   ::: : :: ::: ::    :
> >
> > Version 2, Build 301 - macosx-unix-gnu-ppc - [ libffi dload ptables ]
> > (c)2000-2005 Felix L. Winkelmann
> > #;1> (define ht (make-hash-table))
> > #;2> (hash-table-update!/default ht 'x add1 0)
> > #;3> (hash-table-ref ht 'x)
> > 0
>
> The correct return value would be 1 because SRFI-69 states:
>
> > Procedure: hash-table-update! hash-table key function [ thunk ] => undefined
> >
> > Semantically equivalent to, but may be implemented more efficiently
> > than, the following code:
> >
> > (hash-table-set! hash-table key
> >                  (function (hash-table-ref hash-table key thunk)))
>
> This means, that "function" has to be called, even if the key is not
> present in the hashtable, which CHICKEN fails to do.
>
> A patch fixing extras.scm (created with darcs send) is attached.
>
> cu,
> Thomas
>
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