Hi, Laurent,
Your suggestion of manually piping intermediate results works. Thank you
very much!
Tuba
On Thu, Jul 28, 2011 at 3:44 AM, Laurent PETIT <laurent.pe...@gmail.com>wrote:
> Hi,
>
> 2011/7/28 Tuba Lambanog <tuba.lamba...@gmail.com>
>
>> Hello,
>>
>> I'm trying to pass a variable through a series of functions, which may
>> change the value of the variable. However, the next function in line
>> uses the original value, rather than the changed value. Here's a
>> pseudo-code of what I'm doing.
>>
>> (defn process-1 [s]
>> ; change value of s then return it
>> s)
>>
>> (def s "something")
>> (do
>> (process-1 s) ; variable s is changed here
>> (process-2 s)) ; process-2 uses the original value of s, not the
>> return value from process-1
>>
>>
> beware, "change" in the clojure world means "computing a new value based on
> an old one" (as opposed to creating a new value "almost from scratch").
>
> So for example, when you add an element to a map :
> (def m1 {:a 1})
> (def m2 (assoc m1 :b 2))
>
> you're really creating a new value.
> People will sometimes say they "change" m1, but it's not true, it's more to
> say that m2 is derived from m1 (sharing most things with m1).
>
> So you need to "pipe" the return value of process-1 into process-2.
>
> The "manual way" to do the pipe :
> (let [s-p1 (process-1 s)
> s-p2 (process-2 s-p1)]
> s-p2)
>
> The "short" way (preferred in your case) :
> (-> s process-1 process-2)
>
> HTH,
>
> --
> Laurent
>
>
>> Thanks for the help.
>>
>> Perhaps a sub-forum for beginners? Kind of embarrassing to ask here
>> questions that are so newbie-ish.
>>
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>
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