C#•4y ago

TSelf generic confusion [Answered]

Thinker · 2022-10-11T16:13:44.522Z

So I'm trying to implement an `IFunctor` interface (so I know I'm kind of doomed from the start), but this is what I have currently: ```cs public interface IFunctor where TSelf : IFunctor { IFunctor Map (Func f) where USelf : IFunctor ; } public readonly struct Maybe : IFunctor , T> { // ... IFunctor IFunctor , T>.Map (Func f) { // Should actually apply the func, but just for demonstration rn return new Maybe (); } } ``` It's ugly as hell, I know. I'm getting an error on `new Maybe ()` saying it can't implicitly convert from `Maybe ` to `IFunctor `, except `Maybe ` should implement `IFunctor `, right?

So I'm trying to implement an

IFunctor

IFunctor

IFunctor

IFunctor interface (so I know I'm kind of doomed from the start), but this is what I have currently:

public interface IFunctor<TSelf, T> where TSelf : IFunctor<TSelf, T>
{
    IFunctor<USelf, U> Map<USelf, U>(Func<T, U> f) where USelf : IFunctor<USelf, U>;
}

public readonly struct Maybe<T> : IFunctor<Maybe<T>, T>
{
    // ...

    IFunctor<USelf, U> IFunctor<Maybe<T>, T>.Map<USelf, U>(Func<T, U> f)
    {
        // Should actually apply the func, but just for demonstration rn
        return new Maybe<U>();
    }
}

public interface IFunctor<TSelf, T> where TSelf : IFunctor<TSelf, T>
{
    IFunctor<USelf, U> Map<USelf, U>(Func<T, U> f) where USelf : IFunctor<USelf, U>;
}

public readonly struct Maybe<T> : IFunctor<Maybe<T>, T>
{
    // ...

    IFunctor<USelf, U> IFunctor<Maybe<T>, T>.Map<USelf, U>(Func<T, U> f)
    {
        // Should actually apply the func, but just for demonstration rn
        return new Maybe<U>();
    }
}

public interface IFunctor<TSelf, T> where TSelf : IFunctor<TSelf, T>
{
    IFunctor<USelf, U> Map<USelf, U>(Func<T, U> f) where USelf : IFunctor<USelf, U>;
}

public readonly struct Maybe<T> : IFunctor<Maybe<T>, T>
{
    // ...

    IFunctor<USelf, U> IFunctor<Maybe<T>, T>.Map<USelf, U>(Func<T, U> f)
    {
        // Should actually apply the func, but just for demonstration rn
        return new Maybe<U>();
    }
}

public interface IFunctor<TSelf, T> where TSelf : IFunctor<TSelf, T>
{
    IFunctor<USelf, U> Map<USelf, U>(Func<T, U> f) where USelf : IFunctor<USelf, U>;
}

public readonly struct Maybe<T> : IFunctor<Maybe<T>, T>
{
    // ...

    IFunctor<USelf, U> IFunctor<Maybe<T>, T>.Map<USelf, U>(Func<T, U> f)
    {
        // Should actually apply the func, but just for demonstration rn
        return new Maybe<U>();
    }
}

It's ugly as hell, I know. I'm getting an error on

new Maybe<U>()

new Maybe()

new Maybe<U>()

new Maybe() saying it can't implicitly convert from

Maybe<U>

Maybe

Maybe<U>

Maybe to

IFunctor<USelf, U>

IFunctor<USelf, U>

IFunctor<USelf, U>

IFunctor<USelf, U>, except

Maybe<U>

Maybe

Maybe<U>

Maybe should implement

IFunctor<USelf, U>

IFunctor<USelf, U>

IFunctor<USelf, U>

IFunctor<USelf, U>, right?

ThinkerOP•10/11/22, 4:22 PM

Tried changing the return type of the interface method to just USelfUSelf but that still causes the same error.

ThinkerOP•10/11/22, 4:25 PM

oh USelfUSelf has no inherent connection to TSelfTSelf

ThinkerOP•10/11/22, 4:25 PM

ughhh

ThinkerOP•10/11/22, 4:26 PM

dammit generics catgrump

ThinkerOP•10/11/22, 4:32 PM

just give us TSelfTSelf already

toddlahakbar•10/11/22, 4:53 PM

What is the intent? Like of the TSelf vs T

ThinkerOP•10/11/22, 4:58 PM

Yes, and that doesn't work

ThinkerOP•10/11/22, 4:58 PM

I.e. it needs something like TSelfTSelf

ThinkerOP•10/11/22, 5:01 PM

Which is why I said "so I know I'm kind of doomed from the start"

ThinkerOP•10/11/22, 5:01 PM

Just had to rubber-duck myself to realize this isn't possible

AccordAPP•10/12/22, 6:14 AM

This post has been marked as answered!

TSelf generic confusion [Answered]

Similar Threads

Similar Threads

Similar Threads