Just as a general comment: just because any of our idiosyncratic functions and
macros aren't accepted for inclusion in Clojure proper does _not_ mean that
they can't find a full and vigorous life in their own libraries. Clojure is
readily extended and improved without adding bits to the language itself, and
Clojure development benefits from a very capable dependency management
infrastructure; take advantage of it!
In this particular case, I'll bet that someone has an arbitrary threading macro
in a library somewhere you can use…or, you can create such a library. Given
the number of times this has come up, I'm certain it would find some love.
- Chas
On Jul 18, 2011, at 8:41 PM, Andreas Kostler wrote:
> 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
>>
>> --
>> You received this message because you are subscribed to the Google
>> Groups "Clojure" group.
>> To post to this group, send email to clojure@googlegroups.com
>> Note that posts from new members are moderated - please be patient with your
>> first post.
>> To unsubscribe from this group, send email to
>> clojure+unsubscr...@googlegroups.com
>> For more options, visit this group at
>> http://groups.google.com/group/clojure?hl=en
>
> --
> You received this message because you are subscribed to the Google
> Groups "Clojure" group.
> To post to this group, send email to clojure@googlegroups.com
> Note that posts from new members are moderated - please be patient with your
> first post.
> To unsubscribe from this group, send email to
> clojure+unsubscr...@googlegroups.com
> For more options, visit this group at
> http://groups.google.com/group/clojure?hl=en
--
You received this message because you are subscribed to the Google
Groups "Clojure" group.
To post to this group, send email to clojure@googlegroups.com
Note that posts from new members are moderated - please be patient with your
first post.
To unsubscribe from this group, send email to
clojure+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/clojure?hl=en
