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

[Thomas Chust]

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

hashtable-update.patches
Description: darcs patches for extras.scm