Re: Attaching an alist to a grob

[Urs Liska]

Am 14.01.2015 um 14:47 schrieb Mattes:
>   
> Am Mittwoch, 14. Januar 2015 13:56 CET, Urs Liska <address@hidden> schrieb:
>   
> > OK, I see.
> > But somehow it feels wrong that
> >
> > #(display annotation? some-obj)
> >
> > doesn't produce #t but the content of "location".
> > Should I ignore that feeling?
> If you intended to write
>
>   #(display (annotation? some-obj))

Oops, yes, that's what I intended to write in the above message.
Of course that's not what I'd write in real code where I'd only need 
#(if (annotation? some-obj)).
> then, yes, ignore that feeling. Scheme, like all Lisps (that I know of)  has 
> generalized booleans,
> so anything that's not explicitly false [1] is considered true. Because of this 
> you hardly ever see
> a litteral #t in Scheme code.

OK. I'll try to internalize this, and of course I'll update the code ASAP.

Thanks again for the different input
Urs

>   Cheers, RalfD
>
> [1] while Scheme considers #f to be the only _false_ value, Common Lisp et al. 
> also consider
>        the empty list '() as a valse value.
>
>
> > Urs
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