On Fri, Feb 13, 2009 at 8:01 PM, Phil Hagelberg <[email protected]> wrote:
>
> wubbie <[email protected]> writes:
>> Hi, do we have labels equiv. in clojure?
>> The code below is from OnLisp. Trying to convert to clj file,
>> but have minor difficulties.
>
> You can use "let" since variables and functions are kept in the same
> namespace.
This is true, but this...
> (defn count-instances [obj lsts]
> (let [instances-in (fn [lst]
> (if (cons? lst)
> (+ (if (= (first lst) obj) 1 0)
> (instances-in (rest lst)))
> 0))]
> (map instances-in lsts)))
...doesn't work. You can't refer to the 'let' local from within the
fn definition. You can however give the fn a name, like thisfn:
(defn count-instances [obj lsts]
(let [instances-in (fn thisfn [lst]
(if (seq lst)
(+ (if (= (first lst) obj) 1 0)
(thisfn (rest lst)))
0))]
(map instances-in lsts)))
That works, but is not very Clojurey. Just for the record, I might do
it more like:
(defn count-instances [obj lsts]
(map #(count (filter #{obj} %)) lsts))
--Chouser
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