Ups, I'm not aware of that thread...I just found a more general threading
operator handy sometimes.
I do kinda agree that we shouldn't necessarily encourage threading in arbitrary
positions.
However, I can't quite follow your second argument.
While it does mean two different things, I don't see the problem with that.
We could use _ instead of :? to indicate we don't care about the 'meaning'.
Anyway, I'll delete this evil hack from my repository ;)
On 19/07/2011, at 10:33 AM, Sean Corfield wrote:
> Requests for a "more general" threading macro are usually met with a
> link to the thread where Rich says this is not needed and we should
> not encourage functions that need threading anywhere except the first
> or last position. I don't have the link handy (sorry).
>
> The usual objection centers around the fact that whatever symbol is
> used for the binding position then becomes a "varying" thing within
> the expression:
>
> (-newthread-> "x"
> (str "y" :? "z")
> (str "a" :? "b")
> println)
>
> Here :? means two different things which seems counter to how Clojure
> works elsewhere...
>
> Sean
>
> On Mon, Jul 18, 2011 at 5:10 PM, Andreas Kostler
> <andreas.koestler.le...@gmail.com> wrote:
>> Maybe you might find this useful
>>
>> (defmacro ->
>> ([x] x)
>> ([x form] (if (seq? form)
>> (with-meta (replace {:? x} form) (meta form))
>> (list form x)))
>> ([x form & more] `(-> (-> ~x ~form) ~@more)))
>>
>> This allows for a more flexible threading operation:
>>
>> user> (-> "c"
>> (third-param "a" "b" :? "d")
>> println)
>> first a second b third c fourth d
>> nil
>>
>> Cheers
>> Andreas
>
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