scala/scala

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Ichoran

@Ichoran

Well, you can always bolt on a typeclass.

Fabio Labella

@SystemFw

why should my DB library extend your custom interface that you use in user code?

Ichoran

@Ichoran

Okay, no, not always. Sometimes you can.

Fabio Labella

@SystemFw

final tagless is basically "bolting on a typeclass", and yeah you can

Ichoran

@Ichoran

Hm, that's an interesting way to look at it. "You are probably going to want a typeclass on here. So look, I've already got it prepared for you."

Maybe final tagless is drilling holes and threading them, so it's bolt-ready :)

("threading" = "tapping", to use correct machining terminology.)

Fabio Labella

@SystemFw

personally the reason I like it is that it's the most boilerplate-free, easy to compose thing to build custom languages/abstractions, and I find that building custom abstractions like that really multiplies my engineering power, since it allows me to craft a world where solving the problem at hand is easy, and what I have is now reduced to the smaller individual problems of implementing the primitives of my abstraction

Luis Miguel Mejía Suárez

@BalmungSan

Hi all, quick question,

Does scalatest provides a way to combine two assertions with an or (xor)?
Basically, I have a collection of values and I want to check that for all values of that collection one of their properties should be either A or B.

Ichoran

@Ichoran

Why not just write the xored statement inside a single property test?

upd

@prayagupd

maybe assert(List("expected value A", "expected value B").contains(actualValue))

Ichoran

@Ichoran

Oh, wait, I see, you mean that for collection X you can't find some values for which collection X has property A and other values where it has property B?

Luis Miguel Mejía Suárez

@BalmungSan

This is the test that I would like to write

  it should "have all rules come from either the Scalastyle or the Scapegaot rules repositories" in new Ctx {
    forEvery(rules) { rule =>
      rule.repoKey shouldBe "sonar-scala-scalastyle" or "sonar-scala-scapegoat"
    }
  }

Sadly it doesn't compile, and I can't find nothing related to combining assertions with ors, will try with ||

upd

@prayagupd

you can do assert(List("sonar-scala-scalastyle", "sonar-scala-scapegoat").contains(rule.repoKey))

in scalatest probably List("sonar-scala-scalastyle", "sonar-scala-scapegoat") should contain rule.repoKey

Luis Miguel Mejía Suárez

@BalmungSan

@prayagupd Well surely I can, and it does what I wanted, I just was expecting some nicer DSL...

I think I had a similar problem a few months ago and I solve it that way, so I was thinking it was a repetitive enough requirement to have an especial treatment.

Anyways, Thanks a lot :+1:

upd

@prayagupd

should contain is not a nice DSL? :)

there might be OR operator too i think

Josh

@joshlemer

@BalmungSan you can do:

rule.repoKey should matchPattern {
  case "foo" => 
  case "bar" => 
}

Luis Miguel Mejía Suárez

@BalmungSan

@prayagupd In the case when I want to check a collection contain some value it is, but for an OR of two assertions, IMHO, it is not.
I can't find that OR operator.

@joshlemer Oh, it looks better, thanks :)

Rob Norris

@tpolecat

10% write your tests

80% figure out the #$(&*$&#^ DSL

10% throw things

upd

@prayagupd

here is using or operator

"sonar-scala-scapegoat" should (be ("sonar-scala-scalastyle") or be ("sonar-scala-scapegoat"))

http://www.scalatest.org/user_guide/using_matchers#creatingMatchersUsingLogicalOperators

i dont know how nice DSL is it :)

Josh

@joshlemer

wow!

Luis Miguel Mejía Suárez

@BalmungSan

@tpolecat your comments always make my day :laughing:
I agree in not overusing operators, I haven't define one since I first learn Scala

But, Or is not so bad ;)

@prayagupd Wow, How can I missed that... sorry :confused:

AmirSarvestani

@AmirSarvestani

Hi Everyone, I'm thinking about a way to create One single object from a sequence of objects, Is that possible?

Like this , Seq[IncomeAndExpense] => Income( ) ; where attributes of income are fields in records from Income and expense

Ghost

@ghost~54f837fe15522ed4b3dcd6a3

I think you're looking for fold.

AmirSarvestani

@AmirSarvestani

Thanks! I'll try that

upd

@prayagupd

@AmirSarvestani you can. it also depends how you want to transform?

def income(incomeEx: Seq[IncomeAndExpense]): Income = Income(incomeEx.map { _.amount }.sum)

AmirSarvestani

@AmirSarvestani

Thank you guys, I'll lookm into it

ethicalbeginner

@nitishram

hi all

how to read xml in scala

Seth Tisue

@SethTisue

the scala-xml library may be suitable for light usage (reading config files and such), but you shouldn’t assume it’s industrial strength (for large files, for ingesting arbitrary XML from unknown sources, for lesser-used XML features, and so forth). for heavy/demanding XML work you may need to just use a Java library. there isn’t a Scala-based solution with a sterling reputation

I’m not especially expert on this subject but I’m answering since no one else has.

ethicalbeginner

@nitishram

@SethTisue what is the java API ?

ethicalbeginner

@nitishram

how to read and parse xml in scala using DOM parser

RoelofWobben

@RoelofWobben

good morning all

AmirSarvestani

@AmirSarvestani

@nitishram xml.XML.loadString(objectString)

It gives you a NodeSeq

You can find Xml processing here as well. https://alvinalexander.com/scala/xml-parsing-xpath-extract-xml-tag-attributes

RoelofWobben

@RoelofWobben

can I improve this :

def earliestFilm:Option[String]  = directors.filter(_.lastName == "McTiernan").flatMap(_.films).sortWith(_.yearOfRelease < _.yearOfRelease).headOption.map(_.name)

I have to find the earliest film of McTiernan

AmirSarvestani

@AmirSarvestani

I think you can change filter with headoption fo find with contains

RoelofWobben

@RoelofWobben

@AmirSarvestani how do you see this

AmirSarvestani

@AmirSarvestani

directors.find(.lastName.contains("McTiernan")).flatMap(.films).sortWith(.yearOfRelease < .yearOfRelease).map(_.name)

Try this see if it works. If you use Intellij it also recommends you. See how it goes

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