[REBOL] Re: "piping" functions
From: compkarori:gma:il at: 24-Nov-2005 2:35
back tail series
returns the series one back from the end
so, you should be looking for
butlast: func [series][
copy/part series index? back tail series
]
On 11/24/05, Jean-Francois Allie <jf_allie-hotmail.com> wrote:
>
> Thanks Graham, it is very short indeed!
>
> butfirst: func [series][
> copy next series
> ]
>
> Your version made me realise I had misinterpreted the effect of the "index"
> functions like "back" and "next". You see I thought they returned the index
> position, when in fact, they return the whole series but only show its
> valuesstarting at the position of the index. I think a sliding window would
> be a better metaphor then the arrow pointing at the position.
>
> Unfortunately, this "sliding window" model breaks down in the following
> function where "back tail series" seems to return an index. But when you
> check the type of "back tail series" it answers "block".
>
> Is it a case where we will need both the wave and the particule models to
> understand the phenomenon? What's going on?
>
> many thanks
>
> butlast: func [series][
> copy/part series back tail series
> ]
>
> >>num: [1 2 3 4]
>
> == [1 2 3 4]
>
> >>butlast num
>
> == [1 2 3]
>
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--
Graham Chiu
