Dependency Injection (DI) in Scala with Play [closed] - scala

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I know a few ways to use DI in Scala:
Cake pattern
Macwire
What approach is the most suitable for multi layer application with Play?
I incline to using of macwire in my app.
UPD
Solution which fitted for me:
solution of this problem was leveraging of Macwire lib, but you can combine it with another approaches like pure functional style with monads (like Reader monad)

at my job we use macwire for DI with play and it works smoothly. we used to use cake pattern, but we found that it had more boilerplate than the macwire approach, the compiler errors were harder to interpret, the concept was harder to teach, and cake often triggered full recompiles (whereas we experience much better incremental recompilation with macwire. don't quote me on this one, our switch occurred between 2.10 => 2.11, and i believe there were some improvements from that).
it's hard to answer your question fully though without more details about what you're looking for exactly. care to elaborate?

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Does using a library like cats make upgrading to dotty more or less difficult? [closed]

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If I use cats in my scala project, would it make migrating to dotty easier or difficult?
I'm not too sure of the ramifications of using a library like this and how hard it will be to eventually migrate over to dotty.
Using any library at all will force you to wait until it is released for Dotty.
For many libraries it will be a smooth migration if they don't use type system intensively, some will have to make some adjustments to provide support for new types, and all macros will need a total rewrite.
AFAIR Cats are making preparations for Dotty (you can see that they even have tests for it). But there is also the rest of TL ecosystem and each part of it will have to prepare for migration individually (while depending on its upstreams).
Personally, I wouldn't expect to migrate to Dotty in production for the first half a year. I would give some time to library author to migrate and test their changes. For now some attempts are being made, but since, not everything is set in stone yet, some libraries prefer to wait till right-before-the-release before they start migration.

Scala beginner has some questions [closed]

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I'm going to learn Scala, I already have experience in programming. But I have some questions.
When I create a Project in IntelliJ there I must choose between sbt, Lightbend Project start and IDEA. What should I choose and what's the difference between them?
After I have created a Project, I have to create a Scala Class, right? Then I have to choose between Class, Object and Trait.
What is the difference between them?
3.Are there any other things they are good to know?
Best regards Lockna
The simplest thing to choose would be IDEA. IntelliJ will compile the project for you and you shouldn't have to do much to get it working. If you want to learn Scala and a popular build system at the same time, use SBT. It's going to be too much information to ingest at once though, so I wouldn't recommend it if you're an absolute beginner in Scala/functional programming.
Well, perhaps you should read about Scala. That's a Scala 101 question. It's already well documented on the internet, probably a thousand times, and it's not valuable to add another one here.

Is the Cake Pattern missing from Haskell? Why and when would I need to use the Cake Pattern in Haskell? [closed]

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Reading this question and this thread on Reddit inspired me to ask:
Why don't people in the Haskell community seem to be missing Scala's Cake Pattern? Why is the lack (or cumbersomeness) of a Cake Pattern in Haskell not a such a big issue?
The Cake Pattern is meant to help with large (scalable) systems/programs. Is it possible that systems created with Scala tend to be much larger than systems created with Haskell? This in turn might explain why the Cake Pattern is so important in the Scala world and its lack is not such a big issue in the Haskell world?

Using Scala in the real world [closed]

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Question Context: Where there is an exiting Java application or a new project development that is to be written in mostly Java.
We know that we can use Scala from Java and vice versa.
What specific system features are more suited for functional programming. I mean I wouldn't use Scala just because it has a nice feature of executing a passed-in function implementation over the items of a collection nor would I use Scala just for its object orientation capabilities I would just use Java for that.
So going beyond the nice and interesting features of Scala what set of system features make a compelling case to use Scala on a Java project?
where to start, and where to end?
pattern matching
case classes
functions (and higher order ones)
great collections
more object oriented than java, avoid common anti-patterns
type inference -> much less noise
many great options in concurrency. Futures in Java are just so useless compared to Scala ones
traits for composing services
Testing with ScalaTest+ScalaCheck is much much better than JUnit/TestNG/
Akka !
The list is just too long.

how do i start learning shapeless concepts in scala [closed]

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I would like to learn about polytypic concepts in Scala, I came across shapeless library what would be the best starting point for learning and applying shapeless.
I don't know if thats an answer you wan't, but the best push for me to start learning/using shapeless was a couple of Miles videos from different Scala conferences :
From flatmap
ScalaNE 2012
ScalaNE 2013
His forgotten blog
And as a big practise - i'm writing a lot using Spray toolkit, it uses shapeless inside. So try to write some web server or some client.
Also a github's wiki contains good intro for the library.
Great idea - try to rewrite some case classes into shapeless records with hlists, it's pretty cool to use it with some JSON converter =). Much of it is some generic kind of stuff wich is not very useful in real project, but if you want better understanding of type level programming, it's really great stuff