Well, it took me a while to perhaps get what you were telling me here.
In my case I I had something like
(defn foo [ & {:keys [bar ... more keys ...] :or {bar 1}} ] ...)
and I wanted to know whether the user had explicilty invoked foo with :bar.
What wasn't clear to me was that :as solved this problem.
Reading http://clojure.org/special_forms#Special Forms--Binding Forms
(Destructuring)-Map binding destructuring
I guess I can see that it's telling me :as shows things that weren't in the
init-form, but that's with hindsight.
So, to emulated common lisp 'supplied-p' semantics, you can check the :as
form, which will **not**
contain :or values for keywords.
E.g.
user> (defn bar [ & {:keys [baz] :or {baz 'baz} :as all-keys} ] (println
baz all-keys))
#'user/bar
user> (bar :bof 1)
baz {:bof 1}
nil
And not that the all-keys form does not show a binding for baz, and that's
what I wanted.
Just fyi in case anybody searches topics for 'supplied-p' again.
On Saturday, June 21, 2014 7:22:13 PM UTC-4, Jason Felice wrote:
>
> If you destructure the parameters like this:
> (defn f [& {:as a-map}] ...)
>
> You can use map primitives on a-map. But you can also supply defaults
> here.
> On Jun 20, 2014 2:14 PM, "Dave Tenny" <dave....@gmail.com <javascript:>>
> wrote:
>
>> What is the commonly accepted technique for declaring/using 'supplied-p'
>> type lambda list functionality in clojure?
>>
>>
>> http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html
>>
>>
>> I have some clojure functions with a large number of keywords and various
>> defaults, I want to know if a keyword was specified by the caller (rather
>> than defaulted) in some cases.
>>
>> Certainly I could implement my own destructuring macros that did this,
>> but I'd like to avoid reinventing a wheel here if I can, and also to know
>> the idiomatic clojure way to do it.
>>
>> Thanks for any tips.
>>
>>
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