Converting sequence from sort into a list

[Dave Tenny]

I have a sequence from a call to 'sort'.
I want a list.

What is the best way to do this?

(apply list (sort ...))?

Will it have problems on large sequence inputs?


I can't use (into () (sort ...))
since that conjoins and ruins the sort order.

[Plínio Balduino]

Hi Dave

Sorry if I didn't get it, but doesn't sort already return a list?

Could explain?

Plínio

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[Gary Trakhman]

I believe what he wants is a persistentlist.  You could get one from (apply list) or more succinctly/esoterically (list* ..)

Sort returns a seq view over the array returned by java.util.Array.sort()

(defn sort

  "Returns a sorted sequence of the items in coll. If no comparator is
  supplied, uses compare. comparator must
  implement java.util.Comparator."
  {:added "1.0"
   :static true}
  ([coll]
   (sort compare coll))
  ([^java.util.Comparator comp coll]
   (if (seq coll)
     (let [a (to-array coll)]
       (. java.util.Arrays (sort a comp))
       (seq a))
     ())))

(class (sort (range 10)))

clojure.lang.ArraySeq

[Gary Trakhman]

Ah, scratch that, list* returns a seq as well.

[Dave Tenny]

Sort returns a seq,  but not necessarily something for which list? is true.

On Fri, May 2, 2014 at 11:01 AM, Plínio Balduino <pbal...@gmail.com> wrote:

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[Dave Tenny]

After nosing around all I've come up with via clojure mechanisms is to use (apply list (sort ...)).

It seems to work well enough for lists of arbitrary size (subject to usual memory/size limitations of large lists).

I also considered some native java abuse such as java.util.Arrays.asList(Enumeration),
though I didn't quickly find a way to convert the clojure.lang.ArraySeq from my sort() in testing to an Enumeration.

Guess I'm set for now, I was just hoping to avoid consing a new list on my sort result in order to get a specific collection type.

[Sean Corfield]

My question would be: why do you specifically need a list? i.e., why isn't a sequence good enough?

Sean

[Dave Tenny]

In my case I was just trying to ensure a list type for a java API, though perhaps the clojure reflection layer would have converted a non list seq to a list to match the call, I don't know.