[REBOL] Re: En Masse block operations
From: joel:neely:fedex at: 16-Oct-2001 12:05
Hi, Tim,
Tim Johnson wrote:
> Hello All:
> I would like to apply the same operation to all members
> of a nested block.
> ;Example:
> blk: [[1 2 3 4] [5 6 7 8] [9 10 11 12] [13 14 15 16 17] "one"]
> blk: do-all blk next ; set all members to next element
> ;result sought:
> >>[[2 3 4] [6 7 8] [10 11 12] [14 15 16 17] "ne"]
Sounds like a job for MAP to me...
>> blk: [[1 2 3 4] [5 6 7 8] [9 10 11 12] [13 14 15 16 17] "one"]
== [[1 2 3 4] [5 6 7 8] [9 10 11 12] [13 14 15 16 17] "one"]
... then ...
map: function [[catch] b [block!] f [function!] /all] [r v] [
r: make block! length? b
foreach c b [
if any [found? v: do [f c] all] [append/only r v]
]
r
]
... and, finally ...
>> map blk func [s][next s]
== [[2 3 4] [6 7 8] [10 11 12] [14 15 16 17] "ne"]
... or ...
>> x: map blk func [s] [next s]
== [[2 3 4] [6 7 8] [10 11 12] [14 15 16 17] "ne"]
>> x: map x func [s] [next s]
== [[3 4] [7 8] [11 12] [15 16 17] "e"]
>> map x func [s] [head s]
== [[1 2 3 4] [5 6 7 8] [9 10 11 12] [13 14 15 16 17] "one"]
HTH!
-jn-
--
This sentence contradicts itself -- no actually it doesn't.
-- Doug Hofstadter
joel<dot>neely<at>fedex<dot>com
