implicit Questions
1
The Scala 3 reference at https://docs.scala-lang.org/scala3/reference/metaprogramming/compiletime-ops.html mentions some "Prolog-like programming style" possible with Scala 3 mataprogramm...
6
I want to use java.time.LocalDate and java.time.LocalDateTime with an implicit Ordered like:
val date1 = java.time.LocalDate.of(2000, 1, 1)
val date2 = java.time.LocalDate.of(2010, 10, 10)
if (dat...
15
Solved
Is it possible to define an implicit conversion of enums in c#?
something that could achieve this?
public enum MyEnum
{
one = 1, two = 2
}
MyEnum number = MyEnum.one;
long i = number;
If not,...
Roane asked 4/11, 2008 at 12:6
1
Solved
I am learning about classes in C++. I came across the following statement from the standard:
During overload resolution, non-static cv-qualified member function of class X is treated as a function...
Disjunct asked 7/4, 2022 at 9:53
3
Solved
I came across this where one of the user comment says:
A constructor cannot be called, it is not a function. It is invoked automatically when a new object is created.
My question is that is the a...
Adalai asked 30/3, 2022 at 16:7
8
Solved
In my application I need to read Qr code. I searched the net and found Zing codes however lots of developers had problem with using it and it seems it is buggy!
If i assume that my customers has q...
Aldred asked 12/1, 2012 at 6:32
2
Solved
I am new to sympy but I already get a nice output when I plot the implicit function (actually the formula for Cassini's ovals) using sympy:
from sympy import plot_implicit, symbols, Eq, solve
x, y...
1
Solved
I want to define equality for some type that can be part of other objects or collections using cats/kitten. I don't want to have to define the equality for every other class.
For example:
import ca...
Fitz asked 16/10, 2021 at 0:2
1
Solved
In Scala 3 summon seems to do the same thing as the old implicitly. But when we dig into actual examples we see that isn't the case. For example
case class A(i: Int, s: String)
val mirror = implic...
1
Solved
I was trying to convert generic type to HList:
trait ToHList[T] {
type Out <: HList
def apply(value: T): Out
}
trait LowPriorityToHList {
implicit def default[T]: ToHList.Aux[T, T :: HNil] =...
2
My application code uses AService
trait AService {
def registerNewUser (username: String)(implicit tenant: Tenant): Future[Response]
}
to register a new user. Class Tenant is a simple case clas...
3
Solved
So, I don't really understand the purpose of using an implicit join in SQL. In my opinion, it makes a join more difficult to spot in the code, and I'm wondering this:
Is there a greater purpose f...
5
I ran this code on a different IDE and it was successful. For some reason I get the above error message on Xcode. I assume I'm missing a header of some kind, but I'm not sure which one.
#include &l...
2
JetBrains Rider does not give me the new value for my watches automatically. Instead, I have to click refresh after every step:
I went to the settings and made sure this option was enabled:
...
Sogdiana asked 15/2, 2018 at 21:30
2
What is the difference between the implicit keyword in Scala 2 and given+using in Scala 3? Is it just that implicit has been split up into two keywords, or are the semantics also different, and if ...
1
Solved
I always thought that context bounds and implicit parameter lists behaved exactly the same, but apparently not.
In the example below, I expect summon1[Int] and summon2[Int] to return the same type,...
Panfish asked 29/11, 2020 at 15:53
1
Solved
I was playing with implicits but I got some behaviour that I don't understand.
I defined a simple class and its companion object (just to make a quick test on implicits) as follows
class SimpleNumb...
Cockfight asked 2/11, 2020 at 18:26
3
Short question:
Is there a way to ask the scala compiler to tell me where a certain implicit used at a given point in a program was declared ?
If not, is there an algorithm that I can follow manu...
Dander asked 29/12, 2016 at 15:14
2
Solved
Following on from Witness that an abstract type implements a typeclass
I've tried to compare these two approaches side-by-side in the code snippet below:
// We want both ParamaterizedTC and WithAbs...
2
Solved
I believe my understanding on this is correct but I'd like to check. When creating typeclasses, it feels neater to have them take a single type parameter, like TypeClass[A]. If the typeclass needs ...
1
Solved
I'm trying to have a code like below:
object MetaData extends CacheParams{}
So, since CacheParams needs implicit val p:Parameters, I tried:
object MetaData (implicit val p: Parameters) extends Cac...
1
Solved
I wonder is it possible to pass implicit params through singletons like that
case class Greet(g: String)
object Foo {
def greet(name: String)(implicit greet: Greet = Greet("Hello")) = p...
2
Solved
I have an example like this:
abstract class IsBaseTC[A] { type Self }
abstract class JustHoldsTypeMember[A] extends IsBaseTC[A]
implicit val doubleHoldsTypeMember = new JustHoldsTypeMember[Double]...
1
Solved
I have a classic Encoder typeclass.
trait Encoder[A] {
def encode(a: A): String
}
I have two questions
Question 1 : where does the divergence comes from :
[error] … diverging implicit expansion f...
1
Solved
Given the following typeclass and some instances for common types
trait Encoder[A] {
def encode(a: A): String
}
object Encoder {
implicit val stringEncoder = new Encoder[String] {
override def ...
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