[REBOL] Re: COLLECTing results
From: brett:codeconscious at: 25-Jul-2003 14:39
---Andrew
> I'm using /Initial for my version of 'Collect, because it's like the
> /Initial refinement in the 'Array function:
Sounds good. I'll do the same.
> And the 'datatype! specification allows me to be weird! :)
I'd thought of preallocated series, but not the datatype spec. I'll copy
that! :^)
---Romano
> Foreach makes copy/deep on the body block to recurse well (repeat does not
> make it)
Ahah. Thank you.
> this can also be:
> reduce ['head pick [insert insert/only] not only 'tail result do
block]
> with a small change it can handle also paren! init value under last betas:
>
> reduce ['head pick [insert insert/only] not only 'tail 'first reduce
> [:result] do block]
The [do block], means that the block will be executed during reduce, which
is too early. I need it to execute only when the outside control function
evaluates it.
I don't understand the issue with the paren! init value. Could you give an
example how this version of my function will not work?
---latest examples
>> for i 1 10 2 collect [i * 10]
== [10 30 50 70 90]
>> foreach [a b] [1 2 3 4] collect [a + b]
== [3 7]
>> foreach w [a b c d] collect [w]
== [a b c d]
>> repeat e [a b c %.txt] collect/initial [e] %file
== %fileabc.txt
>> iota: func [n [integer!]][repeat i n collect/initial [i] make block! n]
>> iota 10
== [1 2 3 4 5 6 7 8 9 10]
---latest version
collect: func [
{Collects block evaluations, use as body in For, Repeat, etc.}
block [block!] "Block to evaluate."
/initial result [series! datatype!] "Initialise the result."
/only "Inserts into result using Only refinement."
] [
if not initial [result: block!]
result: any [all [datatype? result make result 1000] result]
reduce ['head pick [insert insert/only] not only 'tail result 'do
:block]
]
Regards,
Brett
