(use '[clojure.contrib.generic.functor :only (fmap)])
(defn update-in-wildcard
"Like update-in, but with :* as a wildcard matcher"
([m [k & ks] f & args]
(condp = [(= k :*) (boolean ks)]
[true true] (fmap #(apply update-in-wildcard % ks f args) m)
[true false] (fmap f m)
[false true] (assoc m k (apply update-in-wildcard (get m k) ks f
args))
[false false] (assoc m k (apply f (get m k) args)))))
This seems to do what you want. I had a similar situation but hadn't
thought of abstracting it out in this way until I read your post. The
condp is somewhat ugly, but I didn't want nested if's checking for the
same condition. If anyone can think of a nicer way of doing the
conditional, let me know.
On Apr 10, 11:32 am, Ozzi Lee <ozzi...@gmail.com> wrote:
> I have a structure of nested Maps and Vectors as follows:
>
> (def document
> {:sections
> [{:items
> [{:quantity 1}
> {:quantity 2}]}
> {:items
> [{:quantity 3}
> {:quantity 4}]}]})
>
> The document has a vector of sections (one, in this case), each
> section has a vector of items (two, here).
>
> I want to increment the quantity of every item in every section. The
> cleanest solution I've found this far is as follows:
>
> (defn update-item [item]
> (update-in item [:quantity] inc))
>
> (defn update-section [section]
> (update-in section [:items] (partial map update-item)))
>
> (update-in document [:sections]
> (partial map update-section))
>
> I'm not concerned about map turning vectors into seqs.
>
> If update-in supported some kind of wildcard, I could write this:
>
> (update-in document [:sections * :items * :quantity] inc)
>
> Where * is a wildcard, meaning "any key".
>
> Does the wildcard idea have any merit? Is there a better way to go
> about this?
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