jvm-languages

问题 As a concrete example for my question, here's a snippet in Python (which should be readable to the broadest number of people and which has a JVM implementation anyway): def memo(f): cache = {} def g(*args): if args not in cache: cache[args] = f(*args) return cache[args] return g How do industrial-strength languages compile a definition like this, in order to realize static scope? What if we only have nested definition but no higher order function-value parameters or return values, à la Pascal

问题 As a concrete example for my question, here's a snippet in Python (which should be readable to the broadest number of people and which has a JVM implementation anyway): def memo(f): cache = {} def g(*args): if args not in cache: cache[args] = f(*args) return cache[args] return g How do industrial-strength languages compile a definition like this, in order to realize static scope? What if we only have nested definition but no higher order function-value parameters or return values, à la Pascal

问题 I'm trying to implement org.joda.time.ReadableInstant. It inherits from a generic interface, but apparently that shouldn't matter. The interface is: public interface ReadableInstant extends Comparable<ReadableInstant> { long getMillis(); Chronology getChronology(); DateTimeZone getZone(); int get(DateTimeFieldType type); boolean isSupported(DateTimeFieldType field); Instant toInstant(); boolean isEqual(ReadableInstant instant); boolean isAfter(ReadableInstant instant); boolean isBefore

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 7 years ago . I just stumbled upon groovy++ and found it quite interesting. Unfortunately it seems that it's not further developed? According to github the last commit was over a year ago. The mailing list is totally inactive and the last message was back in april. There are no recent news about it. Has the project moved and

问题 Since Google App Engine will soon full support Java: Would it be possible to run Ruby on Rails on Google App Engine? Or the limitations imposed by the AppEngine runtime will affect the JRuby implementation? What about other languages such as Groovy, Clojure, Scheme? Are there any effort to support .net and C# in JVM?? I think this would create a NEXT level on webdevelopment. 回答1: This is already possible. Its not perfect, but I would expect rapid improvement. More information: Official

问题 Given the following constructs for defining a function in Scala, can you explain what the difference is, and what the implications will be? def foo = {} vs. def foo() = {} Update Thanks for the quick responses. These are great. The only question that remains for me is: If I omit the parenthesis, is there still a way to pass the function around? This is what I get in the repl: scala> def foo = {} foo: Unit scala> def baz() = {} baz: ()Unit scala> def test(arg: () => Unit) = { arg } test: (arg:

问题 What's a prefereed way to download Scala , via scala-lang.org, can it be added directly by the Eclipse IDE or how to add Scala to Eclipse IDE? Is there a convention on how to add a JVM language? Update I could add Clojure and Scala from Help...install new software so now I can create those kinds of projects: 回答1: You typically install a plugin for that language using Eclipse's build in plugin language. for instance for Clojure you can search the plugin manager for "counter clockwise" to get

问题 In Scala, I can declare an object like so: class Thing object Thingy extends Thing How would I get "Thingy" (the name of the object) in Scala? I've heard that Lift (the web framework for Scala) is capable of this. 回答1: Just get the class object and then its name. scala> Thingy.getClass.getName res1: java.lang.String = Thingy$ All that's left is to remove the $ . EDIT: To remove names of enclosing objects and the tailing $ it is sufficient to do res1.split("\\$").last 回答2: If you declare it as

问题 Is there anything similar to Python virtualenv for Java or JVM Languages? 回答1: From what I understand, virtualenv enables you to have separate library installation paths, effectively separate "virtual" Python installations. Java doesn't have the concept of a "system-wide installed" library (*) : It always searches the classpath for the libraries to be loaded. Since the classpath can be (and needs to be!) defined for each application, each application can pick-and-choose which libraries and

问题 What is the maximum of number of arguments which can be used by a vararg in java ? I believe there should be some limit and it is not infinite. 回答1: A method (including the static class initializer) can have at most 64k. If the arguments are such that they can be pushed with a single bytecode that is 1 byte long each, you can have something about 64000 arguments on a call. 来源： https://stackoverflow.com/questions/18164255/what-is-the-maximum-of-number-of-arguments-for-varargs-in-java