scala-exercises/scala-exercises

The easy way to learn Scala.

Elliot V Pourmand

@ElliotVilhelm

Evaluation failed : Evaluation failed : org.http4s.client.UnexpectedStatus: unexpected HTTP status: 503 Service Unavailable
is back ))):

Elliot V Pourmand

@ElliotVilhelm

its gone!

Ben McAllister

@benomac

What is the correct answer for "Character Literals can be an escape sequence, including hexidecimal:". I've tried passing everything as strings (which is what they evaluate to in the repl) but it never passes!?,

I've also tried putting them in as char's and without any quotes, still doesn't work?

Ok Got it now.

Anna

@Koala4ka

hello i am new here please can someone explain what do i do wrong? 1 + 2 shouldBe
3

"Hello, " ++ "Scala!" shouldBe
Hello, Scala!
Evaluation failed : Compilation Error ; ERROR -> too many arguments (found 3, expected 2) for method evaluation: (res0: Int, res1: String): Unit at [227, 227, 227]

ml10

@ml10

The REPL and some online tools will remove quotes when displaying strings sometimes, but on scala-exercises you need quotes around the result strings in your answers.

skjain116

@skjain116

I have data in 4 fields - addressId, customerId, fromDate, toDate
I have multiple addresses and for each addresses, multiple customers would have stayed there
So, for example, just for address1, I have the 5 values, i.e. 5 tenants (101,102,103,104,105) - (address1, (101, 250, 350), (address1, (101, 100, 220),(address1, (101, 50, 90),(address1, (101, 175, 400), (address1, (101, 420, 500).
I am trying to group all the tenants who stayed in a given property for overlapping time and provide the overall start and end date of this overall overlapping date range.
For example, accounting for the overlapping dates and using the above values for address "address1" , answer would be
Adress. Customers. Start End
address1 [103] 50 90
address1 [101,102,104]. 100. 400
address1. [105] 420 500

I am currently facing a similar problem. I am undergoing scala spark training and this is part of my training. Any solution that works???

1 reply

Djoa Spring

@djoa

Hi all! Here https://www.scala-exercises.org/scala_tutorial/definitions_and_evaluation in section "CHANGING THE EVALUATION STRATEGY" there is missed step: it should be "9 + 16" before "25".

JuanFerreyra

@JuanFerreyra1

hello, can anybody help me on this exercise?

Dmitry Pevunov

@Darkest

Do exercises actually compile and run? The run button is inactive... and no error is given

ml10

@ml10

I was just able to submit an answer successfully. Make sure there aren’t any script or ad blockers on the page. That has caused issues for some folks in the past.

JuanFerreyra

@JuanFerreyra1

thank you very much

MercedesMonti

@MercedesMonti

hi, which is the result of this exercise: 16.toHexString shouldBe?

fhinze

@fhinze

Should be "10"

The service that validates the results seems to be down. Getting 503 errors.

Hernancito

@hernansaab

How do I reset the answers?

Randall Lionel Kharkrang

@bahbah94

How does this work?

i want to code on chrome

Andrew Ribeiro

@Andrewnetwork

Cool site. Thanks for making it!

Christoph Knabe

@christophknabe

How can I delete all my accepted answers for the exercises?

Christoph Knabe

@christophknabe

After a successful run of an exercise you can at least re-edit the answer fields and delete each answer individually.

Solomon Yu

@sqr00t

Hi, I'm unable to login to github using Brave browser due to "invalid code" error. Works fine with other browsers though.

Capitan Empanada

@ivanlp10n2

I had errors with the last one of Higher Order function so I changed the browser, It was compiling ok on my repl. I had to rewrite it in chrome to make it work :)

Capitan Empanada

@ivanlp10n2

I can't see any field to complete in cats/Eval section :(

Ruslan Krivoshein

@ruslankrivoshein

Could anyone explain me, what is the function sum in the exercise of "Higher Order Functions"? I solved it, but can't understand why so

Fernando

@nandotorterolo

Hi, how are you?

Is is expected that if I do a clean fork, and clone, and compile.

compile task works?
(Compile-generated-exercises / generateExercises) java.lang.ClassCastException: class sbt.internal.inc.MappedVirtualFile cannot be cast to class java.io.File (sbt.internal.inc.MappedVirtualFile is in unnamed module of loader sbt.internal.MetaBuildLoader @40f08448; java.io.File is in module java.base of loader 'bootstrap')

tried with:

"sbt-exercise" % "0.6.7"
-"sbt-exercise" % "0.7.1"

Fernando

@nandotorterolo

at scala.collection.TraversableLike.$anonfun$map$1(TraversableLike.scala:286)
[error] at scala.collection.Iterator.foreach(Iterator.scala:943)
[error] at scala.collection.Iterator.foreach$(Iterator.scala:943)
[error] at scala.collection.AbstractIterator.foreach(Iterator.scala:1431)
[error] at scala.collection.IterableLike.foreach(IterableLike.scala:74)
[error] at scala.collection.IterableLike.foreach$(IterableLike.scala:73)
[error] at scala.collection.AbstractIterable.foreach(Iterable.scala:56)
[error] at scala.collection.TraversableLike.map(TraversableLike.scala:286)
[error] at scala.collection.TraversableLike.map$(TraversableLike.scala:279)
[error] at scala.collection.AbstractTraversable.map(Traversable.scala:108)
[error] at org.scalaexercises.plugin.sbtexercise.ExerciseCompilerPlugin$.$anonfun$generateExercisesTask$13(ExerciseCompilerPlugin.scala:214)
[error] at cats.syntax.EitherObjectOps$.catchNonFatal$extension(either.scala:338)
[error] at org.scalaexercises.plugin.sbtexercise.ExerciseCompilerPlugin$.invokeCompiler$1(ExerciseCompilerPlugin.scala:209)
[error] at org.scalaexercises.plugin.sbtexercise.ExerciseCompilerPlugin$.$anonfun$generateExercisesTask$33(ExerciseCompilerPlugin.scala:247)
[error] at cats.instances.ListInstances

KaTeX parse error: Can't use function '$' in math mode at position 5: anon$̲1.$anonfun$trav…: anon$1.$anonfun$traverse$2(list.scala:78)
[error]         at cats.instances.ListInstances

anon$1.loop$2(list.scala:68)
[error] at cats.instances.ListInstances

KaTeX parse error: Can't use function '$' in math mode at position 5: anon$̲1.$anonfun$fold…: anon$1.$anonfun$foldRight$2(list.scala:70)
[error]         at cats.Eval$.advance(Eval.scala:271)
[error]         at cats.Eval$.loop$1(Eval.scala:350)
[error]         at cats.Eval$.cats$Eval

evaluate(Eval.scala:368)
[error] at cats.Eval$Defer.value(Eval.scala:257)
[error] at cats.instances.ListInstances

KaTeX parse error: Can't use function '$' in math mode at position 5: anon$̲1.traverse(list…: anon$1.traverse(list.scala:77)
[error]         at cats.instances.ListInstances

anon$1.traverse(list.scala:16)
[error] at cats.Traverse$Ops.traverse(Traverse.scala:19)
[error] at cats.Traverse$Ops.traverse$(Traverse.scala:19)
[error] at cats.Traverse$ToTraverseOps

KaTeX parse error: Can't use function '$' in math mode at position 5: anon$̲2.traverse(Trav…: anon$2.traverse(Traverse.scala:19)
[error]         at org.scalaexercises.plugin.sbtexercise.ExerciseCompilerPlugin$.$anonfun$generateExercisesTask$32(ExerciseCompilerPlugin.scala:247)
[error]         at scala.util.Either.flatMap(Either.scala:341)
[error]         at org.scalaexercises.plugin.sbtexercise.ExerciseCompilerPlugin$.$anonfun$generateExercisesTask$30(ExerciseCompilerPlugin.scala:246)
[error]         at scala.util.Either.flatMap(Either.scala:341)
[error]         at org.scalaexercises.plugin.sbtexercise.ExerciseCompilerPlugin$.$anonfun$generateExercisesTask$27(ExerciseCompilerPlugin.scala:243)
[error]         at scala.util.Either.flatMap(Either.scala:341)
[error]         at org.scalaexercises.plugin.sbtexercise.ExerciseCompilerPlugin$.$anonfun$generateExercisesTask$1(ExerciseCompilerPlugin.scala:240)
[error]         at scala.Function1.$anonfun$compose$1(Function1.scala:49)
[error]         at sbt.internal.util.$tilde$greater.$anonfun

u2219$1(TypeFunctions.scala:62)
[error] at sbt.std.Transform

KaTeX parse error: Can't use function '$' in math mode at position 5: anon$̲4.work(Transfor…: anon$4.work(Transform.scala:68)
[error]         at sbt.Execute.$anonfun$submit$2(Execute.scala:282)
[error]         at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:23)
[error]         at sbt.Execute.work(Execute.scala:291)
[error]         at sbt.Execute.$anonfun$submit$1(Execute.scala:282)
[error]         at sbt.ConcurrentRestrictions

anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
[error] at sbt.CompletionService$$anon$2.call(CompletionService.scala:64)
[error] at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
[error] at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
[error] at java.base/java.uti

Christoph Knabe

@christophknabe

@nandotorterolo I suppose you have to run it on a Java 8 JDK which is still unmodularized. That was a major break in Java development. The ClassCastException details mention two different Java modules (unnamed vs java.base).

On https://github.com/scala-exercises/scala-exercises I see you should run in on a JDK 8.

Fernando

@nandotorterolo

Thanks for the quick response @christophknabe , using JDK11.
My bad: Prerequisites are in scala-exercises, but they are not on exercises-template. I did not notice this information.

Many thanks

Christoph Knabe

@christophknabe

@nandotorterolo Glad that I could help.

Fernando

@nandotorterolo

Hi, it's me again.
Doing local development, I need a turn around to run exercises, without being signed in on Github, is it possible?
I reviewed all the documentation but unfortunately did't find nothing related
Many thanks

http://localhost:9000/_oauth-callback?error=redirect_uri_mismatch&error_description=The+redirect_uri+MUST+match+the+registered+callback+URL+for+this+application.&error_uri=https%3A%2F%2Fdocs.github.com%2Fapps%2Fmanaging-oauth-apps%2Ftroubleshooting-authorization-request-errors%2F%23redirect-uri-mismatch&state=bd3d1ef4-f435-4d63-b93e-46244195983f

Fernando

@nandotorterolo

body: Missing code or state

1 reply

JamezMercier

@JamezMercier

Hi Scala devs, I see that ScalaFiddle is down, can you suggest any other Scala Fiddle ?

JamezMercier

@JamezMercier

https://scastie.scala-lang.org/ w00t w00t

Fanpeng Kong

@fanpeng-kong

Hi, working on the last exercise in the "SCALA TUTORIAL" (https://www.scala-exercises.org/scala_tutorial/type_classes), how could I refer to the unnamed parameters in val compareRationals: (Rational, Rational) => Int = _1.numer*_2.denom - _2.numer*_1.denom while _1 and _2 apparently are not the right ones to use?

1 reply

Fanpeng Kong

@fanpeng-kong

turned out this piece of information is hard to search than I expected

JamezMercier

@JamezMercier

@fanpeng-kong try that ? https://stackoverflow.com/a/14608449 the idea is to match it but I'm not sure if in your exercise it will work

JamezMercier

@JamezMercier

@fanpeng-kong it does compile
val compareRationals: (Rational, Rational) => Int = {case (x, y) => x.numer*y.denom - y.numer*x.denom}

1 reply

Christoph Knabe

@christophknabe

@fanpeng-kong The key to understanding this is, that compareRationals is a function with two parameters of type Rational, not with one parameter of a pair of Rationals. You can use the function literal syntax, or a case expression as it denotes a partial function, which is also a function. As the case expression was already given by @JamezMercier, here the alternative function literal (aka lambda expression).

val compareRationals: (Rational, Rational) => Int = (x, y) => x.numer*y.denom - y.numer*x.denom

mdolata

@mdolata

Hello all, I contributed to this project last November, will it ever be released? It looks like there are more similar small fixes to the tutorials and IMO would have been useful to deploy them.

Peter Pfister

@peter-pfister

Hi, taking the Cats Scala Exercises and the last topic, Eval, is broken. All of the questions have an answer already filled in and the Submit button is grayed out.

Navjot Singh Chahal

@navjotschahal

Hi everyone is there any Scala lang deve Meetup groups which are actually active and discuss latest developments inscala and host boot camps and organize events.

Prasad Mokkapati

@prasadmokkapati_twitter

Why is
val a = List(1, 3, 5, 7, 9)
// get the length of the list
a.length should equal(5)
failing ?

I get an error
error: value should is not a member of Int

Christoph Knabe

@christophknabe

@prasadmokkapati_twitter Please give the link to the exercise where you have this problem. I did not find it.

2 replies

Where communities thrive

People

Repo info

Activity