I've studied Covariant and Contravariant in C#. and below my code has an error. Error Message: Cannot implicitly convert type 'System.Func' to ...
I've studied Covariant and Contravariant in C#. and below my code has an error. Error Message: Cannot implicitly convert type 'System.Func' to ...
I have tried to write a method that converts any IList of things into a comma-separated list of those things as a string. It looks like this: I wou ...
In Kotlin i am learning about covariant(a subtype can be used in place of a super type). They wrote there something like a rule. but it seems wrong fo ...
As per the definition of contravariance (super class instances will be accepted), my last statement in the below code snippet, should be accepted; but ...
This gives the following error: scala> TP(Sym[M1]{4},new N1()) java.lang.ClassCastException: class N1 cannot be cast to class scala.Product ( ...
As this is not so famous concept, I will make a little intro. Covariant return type of a method is one that can be replaced by a "narrower" type w ...
I am trying to build the following architecture: I want to reorganize the following code in a way I would be able to call a function not only for C ...
I have this piece of code: I know there are some errors like the covariant return type in or that b.metodo3(); doesn't exist, but my question ...
I've been recently learning Kotlin, while having some questions with covariant type. The sample code is here. I have Option and Option2 both having a ...
I have a dataset that have samples with / without treatment and their ages at death and gender. All the samples are dead. I want to test if the treatm ...
It means define trait Option[T] is same as trait Option[+T]. It's easy to consider val humanOpt: Option[Human] can point to a Option[Student] instan ...
For example I have a Processor base class with a method that returns an Object and takes Object as a parameter. I want to extend it and create a Strin ...
When I call serialize with a List containing Symbol and Keyword, the compiler complains type mismatch: Shouldn't List be covariant? how can I ...
I am learning Scala language features. I declare a class with a type parameter. Class Pair has a generic function replaceFirst. I declare a new cla ...
I'm trying to get something working and struggling with the below when using Contravariance. My understanding is Covariance is where you can return a ...
For return types Covariance of the return values are required by the Liskov Substitiution Principle. Lets assume the small type hierarchy for return ...
I have some issues to find a relevant solution to my problem. I have to return some data from a class, and the type of data kind of depends on the cla ...
Hiyas I have this interface: now, when I use this implementation method: I rightfully get a compiler warning about Conflicting parameter types ...
Question Would like to get assistance to understand the cause of the error. The original is from Coursera Scala Design Functional Random Generators. ...
So here's the code: except I get the error on all for case comparisons that: constructor cannot be instantiated to expected type; found : week4 ...