Reflective method invocation
Hi All, I have a question regarding ambiguity in reflective dynamic invocation. In Clojure you can dynamically invoke a method on a Java class like so: (. some-instance bar arg) where bar is a method name. If the type inferencer can't ascertain the type of some-instance a runtime reflective path is used to perform the method invocation. Lets suppose some-instance is of type Foo which has two overloads of method bar: bar(Apple arg) and bar(Orange arg) Now lets suppose Apple is an interface which extends Fruit and so is Orange. Now lastly lets suppose we have a class MutantFruit which implements BOTH Apple and Orange. My question is what method is invoked at runtime for the following code: (. some-instance bar mutant) where mutant is an instance of MutantFruit Regards, Nathan -- -- 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 --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: Reflective method invocation
Thanks for the responses Ambrose and Gary, I suppose the answer is its dependent on JVM implementation/version. As Gary pointed out his code broke on the JVM upgrade. The real question is, if there is ambiguity what should the behaviour be? It seems far from ideal atm, brodering on non-deterministic. One option would be to throw a RuntimeException if multiple methods match. On Tuesday, June 11, 2013 3:14:46 PM UTC+1, Ambrose Bonnaire-Sergeant wrote: Hi Nathan, I just had a quick look at the implementation: I think Clojure picks the first matching method if several are found. https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/Reflector.java#L70 It's probably worth testing this out though. Thanks, Ambrose On Tue, Jun 11, 2013 at 9:24 PM, N8Dawgrr nathan.r...@gmail.comjavascript: wrote: Hi All, I have a question regarding ambiguity in reflective dynamic invocation. In Clojure you can dynamically invoke a method on a Java class like so: (. some-instance bar arg) where bar is a method name. If the type inferencer can't ascertain the type of some-instance a runtime reflective path is used to perform the method invocation. Lets suppose some-instance is of type Foo which has two overloads of method bar: bar(Apple arg) and bar(Orange arg) Now lets suppose Apple is an interface which extends Fruit and so is Orange. Now lastly lets suppose we have a class MutantFruit which implements BOTH Apple and Orange. My question is what method is invoked at runtime for the following code: (. some-instance bar mutant) where mutant is an instance of MutantFruit Regards, Nathan -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clo...@googlegroups.comjavascript: Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+u...@googlegroups.com javascript: For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+u...@googlegroups.com javascript:. For more options, visit https://groups.google.com/groups/opt_out. -- -- 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 --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
defrecord and map
Hi, I'm transforming a recursive form structure to an equivalent structure represented by Clojure records. I want polymorphic dispatch across my newly created structure of records. I also want to be able to apply a function to transform the structure of records, in much the same way as say clojure.walk/walk. The problem is this: the resulting structure loses the record type. A record type of Foobar just becomes a IPersistentMap and loses its Foobar'iness. Is there a mechanism in Clojure to say apply f to all the values of a record and return me a new record of the same type? -- -- 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 --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Puzzle with lazy sequences
If the head is retained on a lazy sequence we have a potential memory leak. I set my JVM memory low, 64mb and ran the following: user (defn test1 [coll] (reduce + coll)) #'user/test1 user (test1 (take 1000 (iterate inc 0))) 499500 user Now if we do: user (defn test2 [coll] [(reduce + coll) (reduce + coll)]) #'user/test2 user (test2 (take 1000 (iterate inc 0))) OutOfMemoryError Java heap space [trace missing] user Which OOMs as expected. The question is, why doens't the first example blow up? What magics happening? I would expect coll which is a function argument to be retained by the garbage collector and hence blow up. -- -- 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 --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: Puzzle with lazy sequences
Hi Thanks for the super fast response, Still a little confused. If coll is set to nil before reduce is called, then what is reduce called with? On Tuesday, February 5, 2013 3:21:14 PM UTC, Herwig Hochleitner wrote: Clojure has a feature called locals clearing, which sets 'coll to nil before calling reduce in test1, because the compiler can prove it won't be used afterwards. In test2, coll has to be retained, because reduce is called a second time on it. 2013/2/5 N8Dawgrr nathan.r...@gmail.com javascript: If the head is retained on a lazy sequence we have a potential memory leak. I set my JVM memory low, 64mb and ran the following: user (defn test1 [coll] (reduce + coll)) #'user/test1 user (test1 (take 1000 (iterate inc 0))) 499500 user Now if we do: user (defn test2 [coll] [(reduce + coll) (reduce + coll)]) #'user/test2 user (test2 (take 1000 (iterate inc 0))) OutOfMemoryError Java heap space [trace missing] user Which OOMs as expected. The question is, why doens't the first example blow up? What magics happening? I would expect coll which is a function argument to be retained by the garbage collector and hence blow up. -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clo...@googlegroups.comjavascript: Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+u...@googlegroups.com javascript: For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+u...@googlegroups.com javascript:. For more options, visit https://groups.google.com/groups/opt_out. -- -- 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 --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Object identity and with-meta
I have unexplained behavior for with-meta.
As far as I understand with-meta should not alter object identity. E.g. if
we have the (= a b) = true for some a and b then
(= (with-meta a ma) (with-meta b mb)) = true should also hold for any ma
and mb.
So why do I get the following behavior at the REPL?
user (def f (partial * 2))
user (= f f)
true
user (= (with-meta f {:a 1}) (with-meta f {:a 1}))
false
Any help appreciated.
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Consuming web services in Clojure
Hi All, Does anyone know of a good simple library to call/consume web-services from Clojure? Note I don't want to create a web-service just call one. -- 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
bug in clojure.lang.ASeq
Hi, stumbled on a nasty bug in Clojure. I'm transferring Clojure objects around using java serialization. When de-serializing a List (clojure.lang.ASeq) it has a hashCode of 0. This means lookups for the object in HashMaps PersistentHashMaps HashSets etc fail. The pre-serialized version of the object has a valid non-zero hashCode. The reason for this is that the cached hashCode value is marked as transient and its default un-cached value is -1. E.g. if he hashCode is -1 compute the hashCode. Of course when an Object is de-serialized any integer transient fields are set to 0. This bug seems to be in all Clojure versions. -- 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: bug in clojure.lang.ASeq
I don't think that's a realistic option for me. I have java objects embedded in the Clojure forms, and the graph is pretty big. On Wednesday, October 10, 2012 2:02:45 PM UTC+1, Stuart Sierra wrote: I would recommend serializing as strings via pr/read over Java serialization, but this still sounds like a legitimate bug. -S -- 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
Idea around SCMs and Clojure
Hi All, One of my first posts to Clojure mailing list. I had an idea around SCMs and Clojure. I'd basically like to put the idea out there and get some feedback. I hope I'm not breaking any etiquette linking to my blog post but I've outlined the idea here: http://clojurian.blogspot.co.uk/ In a nutshell its about why use files for source in Clojure, can we do better? Regards, Nathan -- 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: Idea around SCMs and Clojure
Hi Tassilo, Thanks for your reply. I agree that you need a persistence layer and a VCS provides additional useful capabilities other than persistence. My suggestion isn't to dispense with a persistence or VCS layer. Its more that the REPL connects directly to the VCS layer (which may be remote or local) to retrieve its code artifacts. Persistence would of course be a requirement of the VCS layer. The workflow would change, instead of checking out a filesystem from a VCS and then starting a REPL to load the checked out code, you would first start the REPL and then point it to the VCS endpoint, bypassing the local filesystem. This enables the user to work directly with the VCS inside the REPL without the intermediate local filesystem. In this mode I ask what value would writing source files to a local filesystem provide? Regards, Nathan On Tuesday, July 17, 2012 12:40:09 PM UTC+1, Tassilo Horn wrote: N8Dawgrr nathan.r.matth...@gmail.com writes: http://clojurian.blogspot.co.uk/ In a nutshell its about why use files for source in Clojure, can we do better? Interesting thoughts. With a dynamic, interactive language like Clojure it would certainly be possible to omit files at all and instead hack everything together at the repl where all def-forms would carry all previous versions in their metadata. But I think that's not better than the traditional file-based approach. Version control systems provide far more than just keeping previous revisions. You want do diffs, do branching, merge across different branches on possibly different repositories, etc, etc. That's all already provided by modern VCS in a language independent way, so I hardly see a reason to reinvent the wheel here. And in the end, such an approach will also need some persistency layer, since you don't want to loose your program and all its history if the JVM crashes. Bye, Tassilo On Tuesday, July 17, 2012 12:40:09 PM UTC+1, Tassilo Horn wrote: N8Dawgrr nathan.r.matth...@gmail.com writes: http://clojurian.blogspot.co.uk/ In a nutshell its about why use files for source in Clojure, can we do better? Interesting thoughts. With a dynamic, interactive language like Clojure it would certainly be possible to omit files at all and instead hack everything together at the repl where all def-forms would carry all previous versions in their metadata. But I think that's not better than the traditional file-based approach. Version control systems provide far more than just keeping previous revisions. You want do diffs, do branching, merge across different branches on possibly different repositories, etc, etc. That's all already provided by modern VCS in a language independent way, so I hardly see a reason to reinvent the wheel here. And in the end, such an approach will also need some persistency layer, since you don't want to loose your program and all its history if the JVM crashes. Bye, Tassilo On Tuesday, July 17, 2012 12:40:09 PM UTC+1, Tassilo Horn wrote: N8Dawgrr nathan.r.matth...@gmail.com writes: http://clojurian.blogspot.co.uk/ In a nutshell its about why use files for source in Clojure, can we do better? Interesting thoughts. With a dynamic, interactive language like Clojure it would certainly be possible to omit files at all and instead hack everything together at the repl where all def-forms would carry all previous versions in their metadata. But I think that's not better than the traditional file-based approach. Version control systems provide far more than just keeping previous revisions. You want do diffs, do branching, merge across different branches on possibly different repositories, etc, etc. That's all already provided by modern VCS in a language independent way, so I hardly see a reason to reinvent the wheel here. And in the end, such an approach will also need some persistency layer, since you don't want to loose your program and all its history if the JVM crashes. Bye, Tassilo -- 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: eval seq of forms in another ns
If I remember rightly I solved this by binding *ns* before the eval, e.g. (binding [*ns* some-namespace] (eval form)) On Saturday, March 24, 2012 5:12:29 PM UTC, Renat Yuldashev wrote: How to evaluate each form from the vector of forms inside of the different namespace? I want to have a seq of the evaluation results as a result. Smth. like this: (eval-with-ns 'user ['(+ 1 2 3) '(- 5 4) '(defn f [] [])]) = (6 3 #'user/f) I know about with-ns, but don't know how to use it to solve this problem. -- 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
How to submit clojure bug report?
I found a bug in Clojure core, and know its solution, question is how
to submit a bug report?
FYI here is the bug:
= (.withMeta list {:a 1})
#CompilerException java.lang.UnsupportedOperationException
(NO_SOURCE_FILE:0)
This is reporducable in Clojure 1.2 and Clojure 1.3
This cause of this issue is in:
svn/trunk/src/jvm/clojure/lang/PersistentList.java
with the static method:
public static IFn creator = new RestFn(0){
protected Object doInvoke(Object args) throws Exception{
if(args instanceof ArraySeq)
{
Object[] argsarray = (Object[]) ((ArraySeq)
args).array;
IPersistentList ret = EMPTY;
for(int i = argsarray.length - 1; i = 0; --i)
ret = (IPersistentList)
ret.cons(argsarray[i]);
return ret;
}
LinkedList list = new LinkedList();
for(ISeq s = RT.seq(args); s != null; s = s.rest())
list.add(s.first());
return create(list);
}
};
The withMeta() method should be overriden from AFn where it is
throwing the UnsupportedOperationException. This is being done with
the EmptyList static class further down the file.
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Re: Odd error evaling
Ok not to worry, my environment was bust, a repl restart sorted the issue. On Dec 2, 11:27 pm, N8Dawgrr nathan.r.matth...@gmail.com wrote: Hi Clojurians, I hit the following error today. My environment is Clojure 1.3 (eval (read-string (clojure.repl/source-fn 'keep-indexed))) #CompilerException java.lang.ClassCastException: clojure.lang.Compiler $InvokeExpr cannot be cast to clojure.lang.Compiler$ObjExpr, compiling: (NO_SOURCE_PATH:1) Do other people get the same exception? If so what am I doing wrong? Regards Nathan -- 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
Odd error evaling
Hi Clojurians, I hit the following error today. My environment is Clojure 1.3 (eval (read-string (clojure.repl/source-fn 'keep-indexed))) #CompilerException java.lang.ClassCastException: clojure.lang.Compiler $InvokeExpr cannot be cast to clojure.lang.Compiler$ObjExpr, compiling: (NO_SOURCE_PATH:1) Do other people get the same exception? If so what am I doing wrong? Regards Nathan -- 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
Adding forms to fn
Hi Clojure Group, I'm new to the group, apologies if this topic has been raised before. Basically I'm wondering if there is a reason why the form used to defined a function isn't attached as meta-data to the function. Clojure is a isomorphic language and this capability would really help me out with some libraries I'm building. Clojure forms are pretty compact, much smaller than the compiled byte- code, I can't see it having a big impact on the memory footprint. People might argue that I could provide a local fn macro which captures the form meta-data and calls the clojure.core/fn macro to do the real work. The problem with this approach is that the reader macro #(%) expands to fn*. There is no way of overriding the fn* symbol. What are peoples thoughts? -- 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
