implicit Questions
4
Solved
This is my code for creating Json response for jqGrid and for new keyword for defining cell member I receive following message "No best type found for implicitly-typed array".
var resRows = result...
8
Solved
So far implicit parameters in Scala do not look good for me -- it is too close to global variables, however since Scala seems like rather strict language I start doubting in my own opinion :-...
Augury asked 2/3, 2012 at 9:32
1
Solved
I am writing Test Cases for Spark using ScalaTest.
import org.apache.spark.sql.SparkSession
import org.scalatest.{BeforeAndAfterAll, FlatSpec}
class ClassNameSpec extends FlatSpec with BeforeAndA...
Ashwell asked 21/5, 2017 at 7:9
2
I want to implement a generic weighted average function which relaxes the requirement on the values and the weights being of the same type. ie, I want to support sequences of say: (value:Float,weig...
Underweight asked 13/4, 2017 at 1:52
0
The question is based on the discussion here. This is the setup:
implicit def CToC2(obj: C1): C2 = {
new C2()
}
class C1() {
def f[U](f: (Int, Int) => U): U = f(1, 1)
}
class C2() {
def f[...
1
Solved
I am trying to write a generic weighted average function.
I want to relax the requirements on the values and the weights being of the same type. ie, I want to support sequences of say: (value:Floa...
2
Solved
I have been trying to get a grasp on how implicit parameters work in Scala. As far as I can tell the implicit parameter resolution goes something like this:
Explicitly passing an object to the me...
Triangular asked 15/4, 2012 at 13:40
5
Solved
Let's consider the function:
def foo(implicit a:Int, b:String) = println(a,b).
Now, let us assume that there is an implicit String and Int (implicit val i1=1) in scope but we want to pass an othe...
2
Solved
What's the scope for routes file to find implicits like PathBindable or QueryStringBindable?
For custom types, it's trivial to simply define them in companion object like the following:
case clas...
Adamski asked 31/12, 2015 at 7:53
2
Solved
Given:
implicit class Foo(val i: Int) {
def addValue(v: Int): Int = i + v
}
is it possible apply to it any implicitly?
I get an error here:
<console>:14: error: could not find implicit v...
Sansbury asked 21/11, 2016 at 22:38
1
Solved
I try to write a method which should use a variable from the surrounding scope. The problem is that I cannot access the part of the code where the variable is defined. Something like this:
object ...
1
In Scala 2.12 importing the global execution context and then having another implicit execution context defined in the scope results in an ambiguous implicit, while in 2.11 it works just fine.
imp...
Frottage asked 5/11, 2016 at 20:10
3
Solved
Scala functions has following methods for chaining:
fn1.andThen(fn2)
fn1.compose(fn2)
But how can be written this case:
I have function cleanUp() which has to be called always as last step.
A...
Alcoholicity asked 1/11, 2016 at 10:43
2
Solved
I dont understand why only one out of the three examples below are working? What makes the other two faulty?
class H(implicit a:String, b: Int) {
//Working
}
class H(a:String, implicit b: Int) {...
2
Solved
I just looked at the List.flatMap declaration and was kind of surprised by this.
final override def flatMap[B, That](f: A => GenTraversableOnce[B])
(implicit bf: CanBuildFrom[List[A], B, That]...
Consultant asked 29/8, 2016 at 10:46
3
Solved
I want to enhance all Iterables with some custom code.
For this I wrote the following:
implicit class RichIterable[A, B <: Iterable[A]](b: B) {
def nonEmptyOpt: Option[B] = if (b.nonEmpty) Som...
1
Given a typeclass where instance selection should be performed based on the return type:
case class Monoid[A](m0: A) // We only care about the zero here
implicit def s[T] : Monoid[Set[T]] = Monoid...
Pekin asked 1/6, 2015 at 16:9
0
I fail make an implicit conversion List[A] => List[B], given implicit conversion A => B.
There is a very related question that has a solution but does not work for me. Also, here is a nice do...
Valorie asked 5/7, 2016 at 10:9
4
Solved
Say I have an implicit conversion:
implicit def aToB(a: A):B={
...
}
How can I get this implicit conversion to work on the elements of a List?
If I have:
val listOfA: List[A] ...
and I have ...
Valdes asked 16/9, 2012 at 15:1
1
Solved
I'm using implicit def to build a recursive HList type, to match several kind of higher kinded types of HList. I'm heavily inspired by this post.
This code is working perfectly :
sealed trait HL...
Greed asked 29/4, 2016 at 18:46
1
Solved
I'm trying to design a DSL in Scala. For that, I'd like to create an implicit function on precise strings.
I know that to create an implicit function for any String, I could write:
class StringPlu...
Dumbwaiter asked 14/4, 2016 at 0:0
3
Solved
so found a nice grammar for a calculator and copied it with some lil changes from here:
https://dexvis.wordpress.com/2012/11/22/a-tale-of-two-grammars/
I have two Files: Parser and Lexer. Looks li...
3
Solved
spray-json relies on the presence of an in-scope, implicit JsonWriter[T] when calling toJson on an instance of T.
Say I have a trait with several concrete subtypes, each of which has a JsonWriter...
Cyclone asked 8/3, 2016 at 18:21
1
Solved
Is it somehow possible to declare something like
type F = (Int, Boolean)(implicit String) => Unit
in Scala?
1
Solved
The following Haskell type class and instance:
class Able a where
able :: a -> Int
instance Able Int where
able x = x
is commonly translated to Scala like so:
trait Able[A] {
def able(a:...
Mccallion asked 15/2, 2016 at 21:59
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