I'm still at the beginning in learning scala in addition to java and i didn't get it how is one supposed to do DI there? can or should i use an existing DI library, should it be done manually or is there another way? ...
I'm sure this is a very simple question, but embarrassed to say I can't get my head around it: I have a list of values in Scala. I would like to use use actors to make some (external) calls with each value, in parallel. I would like to wait until all values have been processed, and then proceed. There's no shared values being modified...
What do you lose in practice when you choose a statically-typed language such as Scala (or F#, Haskell, C#) instead of dynamically-typed ones like Ruby, Python, Clojure, Groovy (which has macros or runtime metaprogramming capabilities)? Please consider best statically-typed languages and best (in your opinion) dynamically-typed languages...
I've been reading a lot about how Scala and Erlang does lightweight threads and their concurrency model (actors). However, I have my doubts. Do Scala and Erlang use an approach similar to the old thread model used by Java (green threads) ? For example, suppose that there is a machine with 2 cores, so the Scala/Erlang environment will ...
I want to transform a List[Option[T]] into a Option[List[T]]. The signature type of the function is def lo2ol[T](lo: List[Option[T]]): Option[List[T]] The expected behavior is to map a list that contains only Somes into a Some containing a list of the elements inside the elements Some's. On the other hand, if the input list has at lea...
I have an XML file that I would like to map some attributes of in with a script. For example: <a> <b attr1 = "100" attr2 = "50"/> </a> might have attributes scaled by a factor of two: <a> <b attr1 = "200" attr2 = "100"/> </a> This page has a suggestion for adding attributes but doesn't detail a way to map a current attribute w...
I have been a Java developer for 14 years and have written an enterprise-level (~500 kloc) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered mo...
Edit: Added the fact, that the list is sorted, and realizing 'duplicate' is misleading, replaced that with 'redundant' in the title. I have a sorted list of entries stating a production value in a given interval. Entries stating the exact same value at a later time adds no information and can safely be left out. case class Entry(minute...
What kind of applications are the sweet spot for Scala's lift web framework. My requirements: Ease of development and maintainability Ready for production purposes. i.e. good active online community, regular patches and updates for security and performance fixes etc. Framework should survive a few years. I don't want to write a app in...
I am a student. I learned java during the 2nd year. Now i am in fourth year. I got bored with java and i started to learn Scala. As i learn it, i find it being very complex (although i love it). My question may apply to all new complex language. Why scala is complex? is it because we need to create complex softwares? or i am the only on...
Clojure has a very nice concept of transient collections. Is there a library providing those for Scala (or F#)? ...
Versions: NetBeans 6.8, Scala Kit 0.16.1 When I compile my project, I get the following output: init: deps-jar: Compiling 2 source files to F:\MyProgramming\NorvigSpellChecker\build\classes compile: Created dir: F:\MyProgramming\NorvigSpellChecker\dist Building jar: F:\MyProgramming\NorvigSpellChecker\dist\NorvigSpellChecker.jar Not co...
Suppose I have an ambiguous language expressed in combinator parser. Is there a way to make certain expressions locally greedy? Here's an example of what I mean. import scala.util.parsing.combinator._ object Example extends JavaTokenParsers { def obj: Parser[Any] = (shortchain | longchain) ~ anyrep def longchain: Parser[Any] = zer...
Hi, I'm trying to grasp higher-order-polymophism in scala by implementing a very basic interface that describes a monad but I come across a problem that I don't really understand. I implemented the same with C++ and the code looks like this: #include <iostream> template <typename T> class Value { private: T value; public: Value(c...
Hi, we are considering Scala for a new Project within our company. We have some Junior Programmers with only PHP knowledge, and we are in doubt that they can handle Scala. What are your opinions? Some say: "Scala is a complicated beast!", some say: "It's easy once you got it." Maybe someone has real-world experience? ...
scala> val m = Map(1 -> 2) m: scala.collection.immutable.Map[Int,Int] = Map(1 -> 2) scala> m.map{case (a, b) => (a+ 1, a+2, a+3)} res42: scala.collection.immutable.Iterable[(Int, Int, Int)] = List((2,3,4)) What I want is for the result type to be List[(Int, Int, Int)]. The only way I found is: scala> m.map{case (a, b) => (a+ 1, a+2...
In Scala v 2.7.7 I have a file with class Something[T] extends Other object Something extends OtherConstructor[Something] This throws the error: class Something takes type parameters object Something extends OtherConstructor[Something] { However, I can't do this object Something[T] extends OtherConstructor[Something[T]] I...
Suppose you want to have something like variadic templates (the ability to define n type parameters for a generic class) in Scala. For example you do not want to define Tuple2[+T1, +T2] and Tuple3[+T1, +T2, +T3] but Tuple[T*]. Are there other options than HLists that would support Tuple, Product and Function? ...
Is there a way to use a webservice (REST in this case) as the data source for a Lift application? I can find a number of tutorials/examples of using Lift to provide the REST API, but in my case the data is hosted elsewhere and exported as a REST webservice. Pointers to doc are greatly appreciated. Thanks, Jeff ...
I want to zip even and odd elements in a list to make a list of pairs, like that: ["A", "B", "C", "D", "E", "F"] -> [("A", "B"), ("C", "D"), ("E", "F")] What is the most concise expression to do this in elegant in functional way? ...