On Tue, Feb 7, 2012 at 3:28 PM, Manuel Paccagnella
<[email protected]> wrote:
> I've some questions about destructuring a seq of maps, like:
>
> 1. Is it possible?
> 2. If yes, does it have any sense?
> 3. And if it's possible and is reasonable, how can I do it?
>
> For example, let's say that I have a list of maps like this:
>
> (def something [{:a 1 :b 2}
> {:a 2 :b 5}
> {:a 3 :b 7}])
>
> And let's say that I want a function that returns the sum of all :a values
> of the something seq. I could write the function in this way:
>
> (defn do-sum [some-coll]
> (reduce + (map #(:a %) some-coll)))
>
> Not a big deal, but I wonder if there is a better way to do it.
> Destructuring could be one answer I thought, since I need only the value
> corresponding to the :a key of every map in the seq. But I didn't figured
> out how to do it yet.
>
> Any ideas?
Well, destructuring requires a literal, so you have to know exactly
the structure you're wanting to pick apart. For your specific example,
I can write a destructuring usage that will work, but there's no way
to do it in a general way.
user=>(defn do-sum [[{a1 :a} {a2 :a} {a3 :a}]]
(+ a1 a2 a3))
#'user/do-sum
user=>(do-sum something)
6
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