Re: Space usage of lazy seqs
On Dec 2, 9:09 pm, David Brown wrote: ... > If you're running JDK 6, you can run the virtualvm, or jconsole to get > a better handle on the memory usage, and even dig into what it might > used for. Google does not return useful references to a tool called virtualvm; perhaps you mean VisualVM (jvisualvm)? -Dave -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Java Class Factory
On Dec 2, 11:15 pm, lazy1 wrote:
> Hello,
>
> I'm trying to create a "factory" method for Java classes, however I'm
> doing something wrong.
>
> (import '(java.util Dictionary HashMap))
>
> (def *containers* { :dict Dictionary :hash HashMap})
> (defn new-container
> [type]
> (new (*containers* type)))
>
> (def d (new-container :dict))
>
> The above gives me
> Exception in thread "main" java.lang.IllegalArgumentException: Unable
> to resolve classname: (*containers* type) (t.clj:6)
"new" does not evaluate its arguments, so it is trying to interpret
the form "(*containers* type)" as a classname, which it cannot do.
Another problem with your example is that java.util.Dictionary is an
abstract class, and cannot be instantiated directly; of the two
classes you gave, you will only be able to create instances of
HashMap.
...
> What is the right way to do this?
Aside from the issue with Dictionary being abstract, I think you need
a macro to do what you want to do:
(defmacro new-container [type]
`(new ~(*containers* type)))
-Dave
>
> Thanks,
> --
> Miki
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Re: Is str supposed to be able to output lazy strings?
On Dec 6, 1:20 pm, CuppoJava wrote: > This is expected behavior. > > eg. (str (map identity [1 2 3])) > returns "clojure.lang.lazy...@7861" > > The way to think about it is, (str) asks for the string representation > of an object. The string representation of a lazy sequence in this > case is "clojure.lang.lazy...@7861". > > If you want the string representations of what's inside the lazy seq, > you can use the apply function. > > (apply str (map identity [1 2 3])) > "123" API docs for the arguments to apply - "([f args* argseq])"; so the following is perhaps more straight-forward: (apply str (seq [1 2 3])) => "123" Additionally, the following works too in Cloure 1.0.0: (apply str [1 2 3]) => "123" ...though it does not follow from the API docs, which imply that the last argument to apply should be seq, and "(seq? [1 2 3])" => false. -Dave -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Translation from Common Lisp 2
... > (game-action weld chain bucket attic > (if ((and (have 'bucket) (alter-var-root (var *chain-welded*) (fn ^ Your if-condition is nested one form too deeply; try "(if (and (have 'bucket) ...) ...)" I haven't tried it, so there might be other problems. -Dave -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en To unsubscribe from this group, send email to clojure+unsubscribegooglegroups.com or reply to this email with the words "REMOVE ME" as the subject.
Re: Make a loop in a loop
On Jul 7, 5:06 pm, Isak Hansen wrote: > On Wed, Jul 7, 2010 at 5:00 PM, Lars Nilsson wrote: > > > Maybe > > > (doseq [year (range 1999 2010 1)] > > (doseq [month (range 1 53 1)] > > (print-data year range))) > > You could also do this with dotimes instead of doseq. Doesn't matter > for Ns this small, but creating a range just so you have something to > iterate across is a bit wasteful. That's the beauty of lazy sequences, and range produces a lazy sequence: http://richhickey.github.com/clojure/clojure.core-api.html#clojure.core/range At any point in time, only a single value from each range exists; the other values in the range are either garbage or don't exist (have not been computed) yet. I think this use of range is considered idiomatic Clojure. -Dave -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
