like:
=> (definline pred-transform [obj pred tf]
`(let [o# ~obj]
(if (~pred o#) o#
(~tf o#))))
#'cgws.notcore/pred-transform
=> (pred-transform (println 1) nil? #(println % "."))
1
nil
=> (pred-transform (println 1) #(not (nil? %)) #(println % "."))
1
nil .
nil
On Sat, May 25, 2013 at 3:07 PM, atkaaz <atk...@gmail.com> wrote:
> in which case it does get evaluated twice if form:
> => (pred-transform (println 1) #(not (nil? %)) #(println % "."))
> 1
> 1
> nil .
> nil
>
> => (pred-transform (println 1) nil? #(println % "."))
> 1
> 1
> nil
>
> so maybe a let + gensym would be in order?
>
>
>
> On Sat, May 25, 2013 at 3:04 PM, atkaaz <atk...@gmail.com> wrote:
>
>> Shouldn't it be like:
>>
>> (definline pred-transform [obj pred tf]
>> `(if (~pred ~obj) ~obj
>> (~tf ~obj)))
>> => (pred-transform 1 #(not (nil? %)) println)
>> 1
>> => (pred-transform 1 nil? println)
>> 1
>> nil
>>
>>
>>
>>
>> On Sat, May 25, 2013 at 2:55 PM, atkaaz <atk...@gmail.com> wrote:
>>
>>> just wondering if obj is a form does it get evaluated twice?
>>>
>>>
>>> On Sat, May 25, 2013 at 2:51 PM, Jim - FooBar();
>>> <jimpil1...@gmail.com>wrote:
>>>
>>>> no need for macros... :)
>>>>
>>>> (definline safe-assoc [m k v]
>>>> `(if (contains? ~m ~k) ~m
>>>> (assoc ~m ~k ~v)))
>>>>
>>>> (definline pred-transform [obj pred tf]
>>>> `(if ~(pred obj) ~obj
>>>> ~(tf obj)))
>>>>
>>>> Jim
>>>>
>>>>
>>>>
>>>> On 25/05/13 12:44, atkaaz wrote:
>>>>
>>>> may I see the macro for the latter, if you decide to go that way ? thx
>>>>
>>>>
>>>> On Sat, May 25, 2013 at 2:24 PM, Steven Degutis <sbdegu...@gmail.com>wrote:
>>>>
>>>>> There are two patterns I find in my code that I'm still unhappy with
>>>>> but I don't know how to clean up.
>>>>>
>>>>> The first is: (if (:attr obj) obj (assoc obj :attr something))
>>>>>
>>>>> I'm basically saying, give this hash-map an attribute if it doesn't
>>>>> already have it. And just return the thing with an attribute, regardless
>>>>> if
>>>>> I had to add it or not.
>>>>>
>>>>> This version is ugly because it repeats obj three times. I could
>>>>> write my own macro to de-duplicate it, but I avoid doing that when I can
>>>>> because there's usually a better built-in solution that I just don't know
>>>>> about yet.
>>>>>
>>>>> The second is like it: (if (some-test obj) obj (some-transformation
>>>>> obj))
>>>>>
>>>>> In this one, I just want to return the object, but maybe transform
>>>>> it first. But the reference to obj happens three times! Still feels like
>>>>> it
>>>>> could be cleaned up.
>>>>>
>>>>> Any thoughts on how to clean these up?
>>>>> --
>>>>> --
>>>>> 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 unsubscribe from this group and stop receiving emails from it, send
>>>>> an email to clojure+unsubscr...@googlegroups.com.
>>>>> For more options, visit https://groups.google.com/groups/opt_out.
>>>>>
>>>>>
>>>>>
>>>>
>>>> --
>>>> --
>>>> 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 unsubscribe from this group and stop receiving emails from it, send
>>>> an email to clojure+unsubscr...@googlegroups.com.
>>>> For more options, visit https://groups.google.com/groups/opt_out.
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> --
>>>> 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 unsubscribe from this group and stop receiving emails from it, send
>>>> an email to clojure+unsubscr...@googlegroups.com.
>>>> For more options, visit https://groups.google.com/groups/opt_out.
>>>>
>>>>
>>>>
>>>
>>>
>>
>
--
--
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 unsubscribe from this group and stop receiving emails from it, send an email
to clojure+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.
