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SCALA QUESTIONS

Immutability and shared references - how to reconcile?
Immutability and shared references - how to reconcile?
Hope that helps If X refers to Y, both are immutable, and Y changes (i.e. you replace it with an updated copy), then you have no choice but to replace X also (because it has changed, since the new X points to the new Y, not the old one).This rapidly
TAG : scala
Date : November 26 2020, 07:01 PM , By : yaroslav
In Scala 2.8 collections, why was the Traversable type added above Iterable?
In Scala 2.8 collections, why was the Traversable type added above Iterable?
fixed the issue. Will look into that further I asked David McIver about this on IRC. He said he no longer remembered all of the reasons, but they included:
TAG : scala
Date : November 26 2020, 07:01 PM , By : user3863302
using REST webservices as a datasource for Lift?
using REST webservices as a datasource for Lift?
it helps some times This is not related to Lift in fact. There is a lot of different pieces of information already: HttpClient library as was suggested already, or Dispatch Scala library for accessing HTTP services information on how to cache data in
TAG : scala
Date : November 24 2020, 07:00 PM , By : Islam Atef El-Tiar
Scala passing type parameters to object
Scala passing type parameters to object
help you fix your problem In Scala v 2.7.7 , You could use:
TAG : scala
Date : November 24 2020, 07:00 PM , By : RaSC
Scala for Junior Programmers?
Scala for Junior Programmers?
I wish this helpful for you "My coworkers will not understand Scala" is simultaneously overstating its difficulty and insulting your coworkers.
TAG : scala
Date : November 23 2020, 07:00 PM , By : user3862368
Transient collections for Scala?
Transient collections for Scala?
I wish this help you This sounds like a really great concept for language like F, thanks for an interesting link!When programming with arrays, F programmers use exactly the same pattern. For example, create a mutable array, initialize it imperatively
TAG : scala
Date : November 21 2020, 07:01 PM , By : user3861850
Remove redundant entries, scala way
Remove redundant entries, scala way
it helps some times When you are comparing the consecutive entries in a list, start by zip-ping the list with its tail to get a list of pairs of consecutive elements. Below, I take the first entry from the list, and use collect to simultaneously filt
TAG : scala
Date : November 21 2020, 07:01 PM , By : sauf
SBT cannot find hadoop-aws 3.1.1
SBT cannot find hadoop-aws 3.1.1
hope this fix your issue I was not able to reproduce this error using the following build with sbt 1.2.8:
TAG : scala
Date : November 18 2020, 07:00 PM , By : Mlstratt
How do I implement a collection in Scala 2.8?
How do I implement a collection in Scala 2.8?
Hope this helps I'd have a look at the implementation of collection.immutable.BitSet. It's a bit spread out, reusing things from collection.BitSetLike and collection.generic.BitSetFactory. But it does exactly what you specified: implement an immutabl
TAG : scala
Date : November 14 2020, 07:01 PM , By : warri0r
Load RDD from name
Load RDD from name
Hope that helps There is no such option, because the names are not unique identifiers. There are just a method to attach additional information that will be showed in the UI or debugs string.It is perfectly fine to have:
TAG : scala
Date : November 10 2020, 07:00 PM , By : electyrranical
No pattern match for Seq[Seq[T]]
No pattern match for Seq[Seq[T]]
should help you out You are using the wrong extractor! :+ implies that the first part is part of the (outer) Seq, hence a and b are of type Seq[String] rather than String, while the second part Seq(c,d), and tail are treated as elements, so c and d a
TAG : scala
Date : November 10 2020, 07:00 PM , By : Brando Law
Scala .init method example
Scala .init method example
hop of those help? Can you please explain what init method performs with respect to below list i can see the result of new list says that last sequence is being omitted from the existing list. , .init and .last are the compliments to the .head and .t
TAG : scala
Date : November 10 2020, 07:00 PM , By : gumby
How do I rewrite a for loop with a shared dependency using actors
How do I rewrite a for loop with a shared dependency using actors
it helps some times This is a complement to my comment on shared results for expensive calculations. Here it is:
TAG : scala
Date : November 08 2020, 07:01 PM , By : Sameer
How would you pop an element from the end of a list in scala, and add it to the end of another list?
How would you pop an element from the end of a list in scala, and add it to the end of another list?
Does that help It is easy to compute list4 using init, but list3 needs care because list2 might be empty. This is a safe way to do it:
TAG : scala
Date : November 06 2020, 07:00 PM , By : jfried
Is there an easy way to integrate scaladoc into IntelliJ Idea?
Is there an easy way to integrate scaladoc into IntelliJ Idea?
wish of those help The scaladoc support in IntelliJ is pretty basic for now: some keywords are highlighted in comments, but there is no "generate scaladoc" option in tools. We'll create an issue in the tracker to keep it in mind. .Cheers! Ilya
TAG : scala
Date : November 04 2020, 07:01 PM , By : Armand Choy
Assign same value to multiple variables in Scala
Assign same value to multiple variables in Scala
wish helps you I have 3 variables that have already been initialized, and I want to assign a new value to all three of them. e.g. , It is possible to slightly shorten the var definition code as follows
TAG : scala
Date : October 30 2020, 08:01 PM , By : jrtracing
what is this scala grammar
what is this scala grammar
will help you This is syntax sugar to create a tuple of two elements. The line (new ImmutableBytesWritable, put) is therefore equivalent to new Tuple2(new ImmutableBytesWritable, put)
TAG : scala
Date : October 30 2020, 08:01 PM , By : JKS
Extend case class from another case class
Extend case class from another case class
I wish this helpful for you Unfortunately, I'm afraid it is not possible for case class to extend another case class.The inheritance in "plain" classes would look like:
TAG : scala
Date : October 30 2020, 08:01 PM , By : Soon
Scala println in a for loop
Scala println in a for loop
Hope this helps lines is a single string, not some iterable container of strings. This is because you called the .mkString method on it.When you iterate over a string, you do so one character at a time. So the line in your for is not actually a line,
TAG : scala
Date : October 30 2020, 08:01 PM , By : user3854913
Understanding the diagrams of Product and Coproduct
Understanding the diagrams of Product and Coproduct
it should still fix some issue A product (Tuple in Haskell) is an object with two projections. Those are functions projecting the product to their individual factors fst and snd.Conversly a coproduct (Either in Haskell) is an object that has two inje
TAG : scala
Date : October 25 2020, 07:10 PM , By : Ryan
Wrapping string interpolator macro in another
Wrapping string interpolator macro in another
Does that help I have interpolator xxx is implemented by macro (I do own the code) and returns XXX. I want to implement interpolator yyy when I have function f: XXX => YYY , Try
TAG : scala
Date : October 24 2020, 06:10 PM , By : Gabriele Carvalhal G
How to change "hostname" while running sbt run?
How to change "hostname" while running sbt run?
help you fix your problem sbt run executes the main class in your project. I'm assuming you're running one of the modern web frameworks in your project. Play project you can probably use -Dhttp.address= Akka HTTP - Http().bindAndHandle(routes, "", )
TAG : scala
Date : October 21 2020, 06:10 PM , By : EGoico
How can I get random data generated for scala case classes with the ability to "change some values" for unit t
How can I get random data generated for scala case classes with the ability to "change some values" for unit t
I wish did fix the issue. I think, you are looking for scalaz lense.It'll do what you want.
TAG : scala
Date : October 20 2020, 06:10 PM , By : M.A
compare case class fields with sub fields of another case class in scala
compare case class fields with sub fields of another case class in scala
will help you I have the following 3 case classes: , A simple improvement would be to introduce a trait
TAG : scala
Date : October 19 2020, 06:10 AM , By : I. B. Halliwell
throw exception does not work inside future.map scala?
throw exception does not work inside future.map scala?
Any of those help In the 1st example the exception is just that, a naked exception thrown when encountered. It's not significantly different from something like this.
TAG : scala
Date : October 18 2020, 06:10 PM , By : Bueká Torao García
Scala mockito: Delay Mockito.when().thenReturn(someFuture)
Scala mockito: Delay Mockito.when().thenReturn(someFuture)
it should still fix some issue You can use thenAnswer instead of thenReturn to simulate the wait time. Refer this - https://static.javadoc.io/org.mockito/mockito-core/2.27.0/org/mockito/stubbing/Answer.html
TAG : scala
Date : October 17 2020, 06:10 PM , By : Reytricx
How to create multiple dataframe using same case class
How to create multiple dataframe using same case class
around this issue You can't create two Dataframe using single case class with the same number of columns directly. Assume you have the below case class FlightData. If you created a Dataframe from this case class it will contains 3 columns. However, y
TAG : scala
Date : October 17 2020, 06:10 AM , By : Aleš Pernikář
Lagom: is number of read side shards set per node or within the whole cluster?
Lagom: is number of read side shards set per node or within the whole cluster?
this will help Lagom allows splitting read side processor into shards to scale events processing. , It's the total number of shards for the whole cluster.
TAG : scala
Date : October 16 2020, 06:10 PM , By : Colombus
How can I modify this Ordering?
How can I modify this Ordering?
hop of those help? You need to put an instance of your new Ordering implementation into the implicit namespace.
TAG : scala
Date : October 16 2020, 06:10 AM , By : Vasanthsingh Bhat
reduce RDD having key as (String,String)
reduce RDD having key as (String,String)
it fixes the issue Your reduceByKey must return a BigDecimal - not a tuple. Try this instead:
TAG : scala
Date : October 15 2020, 06:10 PM , By : Cafer Sağlam
Accessibility of scala constructor parameters
Accessibility of scala constructor parameters
should help you out If you have a look at the scala language specification the private modifier allows access
TAG : scala
Date : October 15 2020, 06:10 PM , By : Attila Borza
list Pattern Matching to return a new list of every other element
list Pattern Matching to return a new list of every other element
this one helps. I need to write a function that takes a List such as ("1","2","3") and return every other element in that list into a new list using pattern matching. What would be the correct case statement to get the head element of the list and th
TAG : scala
Date : October 15 2020, 06:10 PM , By : THX Like This
How to Sorting results after run code in Spark
How to Sorting results after run code in Spark
it should still fix some issue If you want to sort your first dataset by the second field, you can use the following code:
TAG : scala
Date : October 15 2020, 06:10 AM , By : JITENDRA BHIMRAO GUR
scala filter list of object if some fields in the object are same
scala filter list of object if some fields in the object are same
I hope this helps you . I have a list of object PersonInfo, if certain fields in the PersonInfo object are same with another PersonInfo object, i'll say these two objects are duplicated. example: , Group them, keep only the duplicates, return as List
TAG : scala
Date : October 14 2020, 06:10 PM , By : Sergiu Tarca
Is there a way New->Scala Class in intellij can default to creating a case class (vs a regular class)?
Is there a way New->Scala Class in intellij can default to creating a case class (vs a regular class)?
This might help you Open File>Settings and go to Files and Code Templates. Click on + and add name Scala Case Class, set extension to scala and provide correct template. You might copy template from Scala Class and modify it accordingly. Click on New
TAG : scala
Date : October 14 2020, 02:00 PM , By : Shams Akrout
Stop the fs2-stream after a timeout
Stop the fs2-stream after a timeout
around this issue I want to use a function similar to take(n: Int) but in a time dimension: consume(period: Duration. So I want a stream to terminate if a timeout occurs. I know that I could compile a stream to something like IO[List[T]] and cancel i
TAG : scala
Date : October 14 2020, 01:00 PM , By : PineApple34
Converting Case Classes with params as Case Classes to Avro Message to send to Kafka
Converting Case Classes with params as Case Classes to Avro Message to send to Kafka
I wish did fix the issue. If you want to use Avro with Scala constructs like case classes I recommend you use Avro4s. This has native support for all scala features and can even create the schema from your model if that is what you want.There are som
TAG : scala
Date : October 14 2020, 04:00 AM , By : JacopoB
Sum of an array elements through while loop
Sum of an array elements through while loop
it helps some times I tried to sum the elements of an array through while loop using the following code , I think what you are trying to do is this:
TAG : scala
Date : October 14 2020, 03:00 AM , By : bathulah
Scala: Using Trait + Companion object to enumerate implementations
Scala: Using Trait + Companion object to enumerate implementations
Does that help It's not an "anti-pattern", it's fine. You can BTW, import the same way at the package level: import com.erik.logic.{A, B, J, Q}, so no need to put them inside the object for that reason (but there is nothing wrong with it either, if y
TAG : scala
Date : October 14 2020, 03:00 AM , By : j harding
Which tools can I use to benchmark a scala code?
Which tools can I use to benchmark a scala code?
it should still fix some issue I would recommend ScalaMeter. It is a microbenchmarking tool, but it does what you want by running the code multiple times, and removing the effects of JIT compiler warm-up, garbage collection, etc. It can also be confi
TAG : scala
Date : October 14 2020, 03:00 AM , By : Donut
can we declare variables and use them in for loop in scala
can we declare variables and use them in for loop in scala
it helps some times You already answered your question to some extent, you don't need to initialize the variable externally, this is enough:
TAG : scala
Date : October 14 2020, 01:00 AM , By : Phaled
Bind columns of 2 different dataframes spark
Bind columns of 2 different dataframes spark
I hope this helps you . It sounds like you want to join two dataframes. To do this you need to have a key that you will bind (join) the columns of a row/s with the columns of another row/s on. You can find more information here: https://www.waitingfo
TAG : scala
Date : October 14 2020, 01:00 AM , By : Santosh B
How to manage the hierarchy of State in Functional Programming?
How to manage the hierarchy of State in Functional Programming?
help you fix your problem Say I have a Student class which has lots of actions: , Inspired by @WillemVanOnsem, here is my solution.
TAG : scala
Date : October 14 2020, 12:00 AM , By : Anand Mallick
Sorting List of values in a RDD in Scala
Sorting List of values in a RDD in Scala
Hope that helps You're nearly there. mapValues, as it's name suggests, applies your mapping function only to the values. Your code looks like you're trying to extract the second element from a key/value tuple, which would, I imagine be throwing error
TAG : scala
Date : October 13 2020, 07:00 PM , By : sambasivarao
Decreasing the compilation time when using shapeless HList
Decreasing the compilation time when using shapeless HList
will be helpful for those in need Scala 2.12.6, Shapeless 2.3.3. , You can cache Shapeless's LabelledGeneric instances like this:
TAG : scala
Date : October 13 2020, 06:00 PM , By : Property Tax Appeal
How to add the schema in a dataframe from a config file
How to add the schema in a dataframe from a config file
help you fix your problem You can find a solution here: How to create a Schema file in SparkBut, you need the type of the columns in your file
TAG : scala
Date : October 13 2020, 05:00 PM , By : Pablo Ponti
scala - mock function and replace implementation in tests
scala - mock function and replace implementation in tests
hope this fix your issue You can't mock Object in Scala, because it's like a static class in java (which you can't mock either). (and you can't mock scala objects not in mockito nor scalamock (maybe in their next version)).But, if you change your obj
TAG : scala
Date : October 13 2020, 03:00 PM , By : s.k
Scala: no-name parameters in function with List and Option
Scala: no-name parameters in function with List and Option
To fix the issue you can do Both of your List examples compile but they don't mean the same thing and don't produce the same results.
TAG : scala
Date : October 13 2020, 03:00 PM , By : Nathan Rittenhouse
How to obtain class type from case class value
How to obtain class type from case class value
I wish this help you Add libraryDependencies += scalaOrganization.value % "scala-reflect" % scalaVersion.value to build.sbt and then you can try
TAG : scala
Date : October 13 2020, 02:00 PM , By : eyad
How do I append an element to a list in Scala
How do I append an element to a list in Scala
I hope this helps you . You are doing in a Java way. In Scala you should avoid mutable variables and use immutable variables as much as possible.A better "Scala" solution for your problem is to do the following:
TAG : scala
Date : October 13 2020, 02:00 PM , By : DisplayName=
How beneficial is Parallel Seq for executing sequence of statements?
How beneficial is Parallel Seq for executing sequence of statements?
I wish did fix the issue. Documentation ("Semantics" section) explains that there are only two possible scenarios that might lead to out-of-order behaviour: Side-effecting operations can lead to non-determinism Non-associative operations lead to non-
TAG : scala
Date : October 13 2020, 08:00 AM , By : Hadeel S A
How can I partition a RDD respecting order?
How can I partition a RDD respecting order?
This might help you I would like to divide a RDD in a number of partitions corresponding to the number of different keys I found (3 in this case): , Assigning your partitions like this
TAG : scala
Date : October 13 2020, 05:00 AM , By : Grotty97
How to extract latest/recent partition from the list of year month day partition columns
How to extract latest/recent partition from the list of year month day partition columns
With these it helps Question : How to extract latest/recent partition from the list of year month day partition columns
TAG : scala
Date : October 13 2020, 04:00 AM , By : HomerSimpson
Fs2 Stream.Compiler is not found (could not find implicit value Compiler[[x]F[x],G])
Fs2 Stream.Compiler is not found (could not find implicit value Compiler[[x]F[x],G])
this will help Fs2 Streamcompile now requires a Sync[F] (see this):
TAG : scala
Date : October 13 2020, 03:00 AM , By : Tirth Joshi
Can you mock a value rather than a method?
Can you mock a value rather than a method?
wish helps you If you know what value you need in accountData Future, why not just pass Future.successful(yourMockedValue)?
TAG : scala
Date : October 13 2020, 03:00 AM , By : F.Negahbani
PureConfig ConfigLoader in Scala
PureConfig ConfigLoader in Scala
I wish this help you You have to match the Scala versions. Cannot mix 2.10 (scala-library) and 2.11 (pureconfig_2.11). Unless you have a good reason, use the latest stable version (2.12.8 currently)
TAG : scala
Date : October 13 2020, 03:00 AM , By : Vladislav Trihub
Scala naming convention for Futures
Scala naming convention for Futures
I hope this helps . I usually don't name methods returning Futures any differently. My reason is that this information is already present in the return type, and will be made clear by any decent IDE upon autocompletion. One exception is in the presen
TAG : scala
Date : October 13 2020, 01:00 AM , By : Andromeda18
case class inheriting another class/trait
case class inheriting another class/trait
wish helps you In scala, a default value for a constructor is compiled as a function which evaluates in the context of the companion object, so
TAG : scala
Date : October 13 2020, 12:00 AM , By : Olena
what is the optimal way to show differences between two data sets
what is the optimal way to show differences between two data sets
fixed the issue. Will look into that further IMHO, I dont understand what do you mean by "optimal" one way is like below.Option 1 :
TAG : scala
Date : October 12 2020, 07:00 PM , By : Yao Lee
Is it safe to catch an Exception object
Is it safe to catch an Exception object
it fixes the issue Addressing the style aspect of the question, Try, as suggested by @LuisMiguelMejiaSuarez, provides a more idiomatic Scala style like so
TAG : scala
Date : October 12 2020, 06:00 PM , By : Praneeth Kanamarlapu

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