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SCALA QUESTIONS

Thread-safely transforming a value in a mutable map
Thread-safely transforming a value in a mutable map
To fix this issue How about this one? Assuming you don't really need a general replace method right now, just a counter.
TAG : scala
Date : November 24 2020, 05:44 AM , By : xtreme3xo
Why does chaining match expressions does not compile?
Why does chaining match expressions does not compile?
This might help you Chaining match expressions does not compile. , If it were allowed, you couldn't do:
TAG : scala
Date : November 24 2020, 05:44 AM , By : Luke
Ebean not persisting foreign keys
Ebean not persisting foreign keys
it fixes the issue I have a simple Entity class like; , There are some innacuracies in provided code. There is
TAG : scala
Date : November 24 2020, 01:01 AM , By : user2957688
Difference between def m(p: T forSome {type T} and def m1(p:Any), is there any ? Explanation needed based on Scala Langu
Difference between def m(p: T forSome {type T} and def m1(p:Any), is there any ? Explanation needed based on Scala Langu
To fix the issue you can do The type of the expression p in p.toString is the skolemization of T forSome {type T}, per SLS section 6.1:
TAG : scala
Date : November 22 2020, 03:03 PM , By : user2956882
macro does not find out enclosing vals
macro does not find out enclosing vals
I wish this help you You don't want the Ident method that takes a symbol, you want Ident.apply, which takes a Name.Replacing Ident(s) with Ident(s.name) (or maybe a little more clearly q"this.$s") will work.
TAG : scala
Date : November 22 2020, 10:56 AM , By : subhash Patil
Spark : how to run spark file from spark shell
Spark : how to run spark file from spark shell
wish of those help I am using CDH 5.2. I am able to use spark-shell to run the commands. , To load an external file from spark-shell simply do
TAG : scala
Date : November 22 2020, 10:56 AM , By : Anna
Flattening a list of lists to a set with exceptions in scala
Flattening a list of lists to a set with exceptions in scala
may help you . This feels like a peculiar problem and I am very new to Scala, so I don't know how to ask the right questions in order to get progress on this problem. , Try this
TAG : scala
Date : November 22 2020, 10:54 AM , By : rdina
flatMap implementation in Scala
flatMap implementation in Scala
wish helps you When you call flatMap and pass the function A => Option[B], flatMap calls map and passes the same function, but the B in flatMap is not same B as in map. For example, if you pass some
TAG : scala
Date : November 22 2020, 10:48 AM , By : user2956042
Confused about a few lines code in a scala official document page
Confused about a few lines code in a scala official document page
like below fixes the issue from and to are methods in class EdgeImpl. They both have zero parameters and a return type of Node. from isn't "assigned" the value of origin per-se. It's just a method that always returns origin.Without reading too much i
TAG : scala
Date : November 22 2020, 10:48 AM , By : user2955995
How to input parameters when running bash command with Scala
How to input parameters when running bash command with Scala
This might help you Could someone give me an advice how to run command as below in scala ?
TAG : scala
Date : November 22 2020, 10:48 AM , By : James Osgathorpe
Location header is lost if max-redirects > 1
Location header is lost if max-redirects > 1
around this issue Apparently I misunderstood the Location header. It comes with redirect response, so when I set up max-redirect > 0 and I have a redirect I get the latest response that is already redirected and it does not have a Location header. Sp
TAG : scala
Date : November 22 2020, 10:40 AM , By : user2955636
Controller Spec is using FakeApplication, but can't load test configuration
Controller Spec is using FakeApplication, but can't load test configuration
this will help The documentation for Play's GlobalSettings.onLoadConfig method states:
TAG : scala
Date : November 22 2020, 10:40 AM , By : Austin Buckler
Scala code analyzer targets case variable names that are identical to the outer matched varables - "suspicous shado
Scala code analyzer targets case variable names that are identical to the outer matched varables - "suspicous shado
will help you In the following code snippet in which the outer match vars (x,y) are case matched by (xx,yy): , This could be confusing:
TAG : scala
Date : November 22 2020, 10:40 AM , By : Gunnar
Why does authorize directive execute after the code it's supposed to protect?
Why does authorize directive execute after the code it's supposed to protect?
may help you . to Gangstead and user3567830 for the answere.As states in the docs
TAG : scala
Date : November 22 2020, 10:38 AM , By : iZax
Scala. Checking if a Type is Comparable
Scala. Checking if a Type is Comparable
I wish this help you I have a simple class which takes a generic type, Eg: , Something like this perhaps?
TAG : scala
Date : November 22 2020, 10:33 AM , By : Thang Nguyen
Does having a private constructor on a value class negate the benefits of a value class?
Does having a private constructor on a value class negate the benefits of a value class?
hop of those help? If "treat as a primitive" here means "avoid allocation", then this indeed will not work, but not because of a private constructor.As mentioned in Value Classes Guied
TAG : scala
Date : November 22 2020, 10:31 AM , By : user2954721
How to transform submitted json in Play 2.0?
How to transform submitted json in Play 2.0?
hop of those help? You're basically dealing with a nested monad, and the main tool for working with such is flatMap, particularly if both options being None has the same semantic meaning to your program:
TAG : scala
Date : November 21 2020, 07:31 AM , By : user2954031
Scala warning match may not be exhaustive
Scala warning match may not be exhaustive
like below fixes the issue When pattern matching, you should account for all possible cases or provide a "fallback" (case _ => ... ). Option can be Some or None, but you're only matching against the None case. If Session.get().getAttribute("player")
TAG : scala
Date : November 21 2020, 07:31 AM , By : user2954000
Pure not a member of objective Promise in PlayFramework
Pure not a member of objective Promise in PlayFramework
I wish did fix the issue. That's using a much older version of the Play libraries. Promise.pure was deprecated in 2.2.x, and removed in 2.3.x. You can use scala.concurrent.Future.successful instead.
TAG : scala
Date : November 21 2020, 01:01 AM , By : Vasilescu Ionut Vale
How to unmarshal POST params and JSON body in a single route?
How to unmarshal POST params and JSON body in a single route?
it should still fix some issue I have this route: , You can just nest the directives:
TAG : scala
Date : November 21 2020, 01:01 AM , By : Cynthia Carlton
Spark:How to use join method?
Spark:How to use join method?
I wish this help you You need to enable to enable Spark implicit convertions by importing org.apache.spark.SparkContext._ to access extra functions available on RDDs of (key, value) pairs.
TAG : scala
Date : November 20 2020, 01:01 AM , By : user2953393
is client thread-safe in Twitter Finagle
is client thread-safe in Twitter Finagle
wish of those help This is client-specific. All clients exported by Finagle are thread-safe, but your own clients may not be if you don't design them to be.
TAG : scala
Date : November 20 2020, 01:01 AM , By : chatzipr
Why is the method accepts only one argument?
Why is the method accepts only one argument?
Any of those help fibs is not a method, it's a value of type Stream[Int].When you write fibs(9), you're calling fibs.apply(9), which, for a Stream, selects an element by its index in the sequence (see here).
TAG : scala
Date : November 20 2020, 01:01 AM , By : sgvavd
Scala Play 2.3 Working with gCloud Storage - any libs to go async?
Scala Play 2.3 Working with gCloud Storage - any libs to go async?
seems to work fine No, The Google API client is just a simple wrapper around REST calls. If you want async, you will need to code that into your app.
TAG : scala
Date : November 19 2020, 01:01 AM , By : user2952616
spray.io strange get/delete/detach directives behavior
spray.io strange get/delete/detach directives behavior
it fixes the issue I don't understand why but it seems that this modification works properly:
TAG : scala
Date : November 19 2020, 12:41 AM , By : Kryptokrates
SBT cannot resolve class declared in src/main/scala in a src/test/scala test class
SBT cannot resolve class declared in src/main/scala in a src/test/scala test class
hop of those help? You forgot the new keyword. Without it, the compiler looks for the companion object named CSVStream, not the class. Since there is none, it complains. Add new and it'll work.
TAG : scala
Date : November 18 2020, 03:49 PM , By : user2951940
Scala typeclass without function argument
Scala typeclass without function argument
seems to work fine I'm currently working on my network library in scala. I encountered something like this: , Prepend an empty parameter list:
TAG : scala
Date : November 18 2020, 03:49 PM , By : Pratik
Configuring actor behavior using typesafe Config and HOCON
Configuring actor behavior using typesafe Config and HOCON
Hope that helps interesting case. If I understood you right, you want to configure Market actor mixing in some MatchingEngine type specified in config?Some clarification: you can't simply mix in dynamic type. I mean if you move MatchingEngine type to
TAG : scala
Date : November 18 2020, 11:13 AM , By : Tatsuo Ikeda
Scalatra: Migrating Jersey Filters to Scalatra
Scalatra: Migrating Jersey Filters to Scalatra
This might help you If you have well defined routes that share a common pattern depending on what you want to do then you could do
TAG : scala
Date : November 18 2020, 11:13 AM , By : user2951495
Compilation error when using Scaldi
Compilation error when using Scaldi
will be helpful for those in need Figured out from the documentationAll forms of inject expect and implicit instance of Injector to be in scope. If
TAG : scala
Date : November 18 2020, 11:13 AM , By : batman
Scalac hanging in phase typer
Scalac hanging in phase typer
will be helpful for those in need Thank you Cvogt, upgrading to 2.11 did the trick. As you said, this is a problem with the 2.10.3 compiler and seems to be fixed now.
TAG : scala
Date : November 18 2020, 01:01 AM , By : Sasquatchahatchie
how to have different source code when cross-compiling Scala with sbt? (changes in MurmurHash)
how to have different source code when cross-compiling Scala with sbt? (changes in MurmurHash)
To fix this issue I am using SBT 0.13.2 (could be e.g. 0.13.5 just as well) and am trying to take a project written for 2.10 and cross-compile it for both 2.9 and 2.10. It uses scala.util.hashing.MurmurHash3, which doesn't exist in 2.9; instead there
TAG : scala
Date : November 18 2020, 01:01 AM , By : user2951198
How to set different scalacOptions per Scala version when cross-compiling using Build.scala?
How to set different scalacOptions per Scala version when cross-compiling using Build.scala?
this will help When building with Scala 2.10 and SBT 0.13.2, I want to have -language:_, but this isn't recognized by Scala 2.9. There's a question about settings different scalacOptions for cross-compilation (Conditional scalacOptions with SBT), but
TAG : scala
Date : November 18 2020, 01:01 AM , By : Ellie Salander
Possible Bug in JDBC?
Possible Bug in JDBC?
I wish this helpful for you I think I found an enduring solution for the problem meanwhile. Since my sql generator needs to stay very flexible I somehow need a way to pass along sql fragments with their corresponding parameters without evaluating the
TAG : scala
Date : November 17 2020, 11:58 AM , By : user2950797
Is there a Scala compiler flag to warn when tail recursion is applied without annotation?
Is there a Scala compiler flag to warn when tail recursion is applied without annotation?
I wish this helpful for you I don't think the compiler has this but IntelliJ offers a "No tail recursion annotation" under Inspections > Scala: General
TAG : scala
Date : November 17 2020, 11:58 AM , By : Adil Elsaeed
scala case class put methods in companion object?
scala case class put methods in companion object?
it fixes the issue I would prefer to put methods in case class. Putting it in companion object sounds like Anemic Domain Model anti-pattern AnemicDomainModel.Moreover you can override case class methods later or extend and mix some traits.
TAG : scala
Date : November 17 2020, 11:52 AM , By : shuang
multiproject sbt doesn't generate file structure
multiproject sbt doesn't generate file structure
help you fix your problem As @vptheron correctly points out, sbt does not generate any project directories, with the exception of the target directory when it produces compiled class files.You might find that functionality in plugins, e.g. np. Also i
TAG : scala
Date : November 17 2020, 04:28 AM , By : sirjoe
Scala "multilevel" abstract class / abstract objects replacement
Scala "multilevel" abstract class / abstract objects replacement
like below fixes the issue I don't think abstract classes are necessary here since it seems like you just want an immutable data structure without any actual inheritance. Nested case classes should do just fine.
TAG : scala
Date : November 15 2020, 06:54 AM , By : RW Beman
Scala, getting the type parameters of a KList as an HList
Scala, getting the type parameters of a KList as an HList
this will help I'm not Miles, but it's possible to accomplish what you're trying to do pretty elegantly with Shapeless's Comapped:
TAG : scala
Date : November 14 2020, 04:51 PM , By : russman
Why does Play refuse form reporting "Cannot resolve method apply with such signature: Missing arguments"?
Why does Play refuse form reporting "Cannot resolve method apply with such signature: Missing arguments"?
like below fixes the issue That's because you exceeded the maximum number of fields for a single tuple (18), here is what the Play doc says:
TAG : scala
Date : November 14 2020, 04:51 PM , By : Mario
How to split string with trailing empty strings in result?
How to split string with trailing empty strings in result?
I wish this help you As Peter mentioned in his answer, "string".split(), in both Java and Scala, does not return trailing empty strings by default. You can, however, specify for it to return trailing empty strings by passing in a second parameter, li
TAG : scala
Date : November 14 2020, 04:51 PM , By : Xander
Scala group by list of list and subtracts grouped values
Scala group by list of list and subtracts grouped values
Hope that helps Below sample data , Consider
TAG : scala
Date : November 14 2020, 04:51 PM , By : leeflow
Scala - Creating a function to produce Unary string or integer values
Scala - Creating a function to produce Unary string or integer values
Hope this helps Hello fellow Scala programmers, , I guess I'll have to go with this solution.
TAG : scala
Date : November 14 2020, 04:48 PM , By : nathanaelphilip
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