I'd use clojure.core/replace
It takes a replacement-map in the form of {before after, ...} and a
collection. It replaces all befores with the corresponding afters:
=> (replace {:answer 42} [:the :answer :to :life])
[:the 42 :to :life]
On Mon, Feb 13, 2012 at 23:16, James <jegathi...@gmail.com> wrote:
> Hi,
>
> I am new to clojure and I am very excited about learning the
> language. I have a question about replacing an element in a list. I
> have elements that look like this :
>
> {:id G__781, :value 1}
>
> The list looks like this:
>
> ({:id G__821, :value 1} {:id G__820, :value 1} {:id G__819, :value 1}
> {:id G__818, :value 1} {:id G__817, :value 1})
>
> I want to update an element in the list by conjoining a new list with
> an updated element. For example, I'll update the head of the list:
> ({:id G__821, :value 10} {:id G__820, :value 1} {:id G__819, :value 1}
> {:id G__818, :value 1} {:id G__817, :value 1})
>
> My update code (it really builds a new list with and replaces the
> updated element) looks like this:
>
> (defn update-id-list [id-list new-id new-id-list]
> (doseq[old-id id-list
> new-id-list (conj new-id-list (choose-id old-id new-id) )]
> (println "New List " new-id-list)) new-id-list)
>
> (defn choose-id[old-id new-id]
> (if (= (:id old-id) (:id new-id)) new-id old-id))
>
> This doesn't work. It never conjoin's elements and ultimately returns
> an empty list. I've tried using various other methods but I keep
> going in circles.
>
> Any ideas why this wouldn't work?
>
> Thanks,
> James
>
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Moritz Ulrich
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