[REBOL] Re: head reverse annoys me
From: hallvard:ystad-oops:as:no at: 17-Dec-2004 10:33
It will not break, since
head head "123"
is identical to
head "123"
i.e. if 'reverse were to do 'head all by itself,
performing an extra 'head on the series won't change
anything. I haven't seen _any_ examples of 'reverse being
used _without_ 'head (situations where scrips might
actually break), as Carl pointed out in his post.
Then there is the current inconsistency in 'reverse:
tuples! and pairs! (since they are not series!) will not
be "empty" after being reversed (see
http://www.rebol.org/cgi-bin/cgiwrap/rebol/ml-display-thread.r?m=rmlHGYB).
And then there are lists! :
>> reverse to-list [1 2 3]
== make list! [1]
>> head reverse to-list [1 2 3]
== make list! [3 2 1]
>> index? reverse [1 2 3] ; block
== 4
>> index? reverse to-list [1 2 3] ; list
== 3
An odd difference, if you ask me. Maybe this could be done
more logical too, if 'reverse's behaviour were to change?
HY
On Thu, 16 Dec 2004 15:29:04 EST
SunandaDH-aol.com wrote:
>Carl:
>
>> I'm not sure if anyone has been annoyed by REVERSE
>>returning
>> the tail position. I know I have. Everywhere I see
>>REVERSE used
>> like this: ... head reverse foo.
>
>Annoying? Yes..
>
>But used? Yes -- quite commonly.
>
>I've scanned a pile of code and found it on several
>occasions.
>
>Typically something like:
>
>if user-display-option = "earliest first" [
> data: head reverse data
> ]
>foreach item data [ .... ]
>
>Sadly, all that code would break.
>
>How about a related word?
>
> invert: func [item] [head reverse item]
>
>Sunanda
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