Oh, wait, my bad... you're getting the keyword args special
destructuring. i.e., you're telling Clojure to expect a map and store
the appropriate keys in the proper symbols
user=> ((fn [{:keys [k]}] (str k)) {:k "Awesome" :l "Beer"})
"Awesome"
user=> ((fn [{:keys [k l]}] (str k l)) {:k "Awesome" :l "Beer"})
"AwesomeBeer"
Not 100% why you're having an issue, gotta think.
On Apr 30, 2:56 pm, Russell Christopher
<[email protected]> wrote:
> Why does this work?
> (defrecord R [k])
> (extend-protocol P R (p [{:keys [k]}] k))
>
> On Fri, Apr 30, 2010 at 2:52 PM, Sean Devlin <[email protected]>wrote:
>
>
>
> > I think you have your destructuring backwards.
>
> > You fn should probably be (fn [{k :keys}] k)
>
> > For example,
>
> > user=> ((fn [{k :keys}] k) {:keys "Awesome"})
> > "Awesome"
>
> > On Apr 30, 2:46 pm, russellc <[email protected]> wrote:
> > > Should this compile?
>
> > > (defprotocol P (p [this]))
> > > (defrecord R [k] P (p [{:keys [k]}] k))
>
> > > java.lang.ClassCastException: clojure.lang.PersistentArrayMap cannot
> > > be cast to clojure.lang.Symbol
>
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