scalaz7 Questions
2
Solved
I'm trying to use Scalaz EitherT with a scala.concurrent.Future. When trying to use it in a for-comprehension:
import scalaz._
import Scalaz._
val et1:EitherT[Future, String, Int] = EitherT(Futur...
Tonguing asked 22/12, 2015 at 1:34
2
did anybody come to piece of code how to properly convert scala's Future (2.10) to new scalaz7 future ? I know hot to convert scalaz future via scala Promise to scala Future, but not sure how to do...
1
Solved
Scalaz State monad's modify has the following signature:
def modify[S](f: S => S): State[S, Unit]
This allows the state to be replaced by state of the same type, which does not work well whe...
Boehmenism asked 19/1, 2016 at 7:30
4
Solved
I'm trying to understand the idea and purpose behind scalaz concurrent package, primarily Future and Task classes, but when using them in some application, it's now far from simple sequential analo...
Te asked 30/10, 2013 at 19:52
1
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I found that there is no more awakeEvery inside scalaz.stream.Process in modern scalaz-stream. How to run something with period then?
Hypersonic asked 29/9, 2015 at 19:13
1
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I have have the following parser to parse arithmetic expressions containing Float and RDD :
import scalaz._
import Scalaz._
def term2: Parser[List[\/[Float, RDD[(Int,Array[Float])]]]] = rep(fa...
Weighin asked 12/7, 2015 at 19:55
2
Solved
Recently, specs2 was updated to version 2.4, which uses scalaz 7.1 instead of 7.0.x now. Once I update my specs2 dependency in my play! 2.3 project to use version 2.4, all tests fail with the follo...
Haemostat asked 13/8, 2014 at 7:20
0
Say I have the following function:
def getRemoteThingy(id: Id): EitherT[Future, NonEmptyList[Error], Thingy]
Given a List[Id], I can easily easily retrieve a List[Thingy] by using Traverse[List]...
Mythological asked 30/4, 2015 at 14:2
1
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Let's take an example from some scalaz-stream docs, but with a theoretical twist.
import scalaz.stream._
import scalaz.concurrent.Task
val converter: Task[Unit] =
io.linesR("testdata/fahrenheit....
Houlihan asked 18/12, 2014 at 15:17
2
I recently asked Map and reduce/fold over HList of scalaz.Validation and got a great answer as to how to transform a fixed sized tuple of Va[T] (which is an alias for scalaz.Validation[String, T]) ...
Airs asked 21/10, 2014 at 13:3
1
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I started out with something like this:
def nonEmpty[A] = (msg: String) => (a: Option[A]) => a.toSuccess(msg)
val postal: Option[String] = request.param("postal")
val country: Option[String...
Bilbrey asked 16/10, 2014 at 17:9
1
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The aim of Semigroup is to make sure Associativity and closure
The aim of monoid is based on Semigroup and provide additional Identity.
When I use |+| semigroup appender, why I have define implicit...
Milone asked 24/8, 2014 at 2:6
2
Is it possible to perform a fold in the State monad in constant stack and heap space? Or is a different functional technique a better fit to my problem?
The next sections describe the problem and ...
Marasmus asked 24/12, 2013 at 7:5
2
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1
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Maybe I'm missing something obvious, but I'm trying to clean up some boilerplate in a project that uses Scalaz 7, and I'm not finding one particular puzzle piece that seems pretty simple and possib...
1
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There's an example of a Scalaz map lens here: Dan Burton calls it containsKey, and it's inspired by the Edward Kmett talk. There is also something called mapVPLens in Scalaz 7 which is useful for m...
Whang asked 16/9, 2013 at 18:49
2
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I have an app that does a lot of calls to different backend systems, and hoping to use for-comprehensions to simplify the process flow across the backend systems.
I'm looking to combine EitherT (s...
Yetty asked 24/7, 2013 at 21:46
1
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I'm trying to use Scalaz 7 Validation in my app. However, I'm having an issue getting the |@| applicative functor to coalesce my failures. Here's the code I have:
type ValidationResult = Validatio...
Durrell asked 17/7, 2013 at 23:15
2
Solved
I'm using Scalaz 7's EitherT to construct for-comprehensions that blend State and \/. So far so good; I get something that's basically:
State[MyStateType, MyLeftType \/ MyRightType]
and that all...
Corset asked 2/7, 2013 at 5:43
1
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Last night in responding to this question, I noticed the following:
scala> val foo: Option[Set[Int]] = Some(Set(1, 2, 3))
foo: Option[Set[Int]] = Some(Set(1, 2, 3))
scala> import scalaz._, ...
3
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I occasionally hit code like this:
val things : List[A \/ B] = ???
val (as, bs) : (List[A], List[B]) = ??? //insert something to do this
or in my current case I want Map[A, B \/ C] => (Map[A,...
1
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I'm struggling with understanding monad stacks and monad transformers with Scalaz7. I feel I'm pretty close to the answer but just can't get my head around a particular step.
The following code lo...
Hotel asked 20/5, 2013 at 21:6
1
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The definition of the scalaz's option monoid is as follows:
implicit def optionMonoid[A: Semigroup]: Monoid[Option[A]] = new Monoid[Option[A]] {
def append(f1: Option[A], f2: => Option[A]) = (...
1
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Let's assume an object constructed using a builder pattern.
This builder pattern would contain a build method focusing on fields validation and then on conversion to the targeted type.
This valid...
Rolanderolando asked 27/2, 2013 at 18:45
3
Solved
I'm trying to use the scalaz iteratee package to process a large zip file in constant space. I have a long-running process I need to perform on each file in the zip file. Those processes can (and s...
Preconscious asked 26/4, 2013 at 3:14
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