C#•3y ago

TSelf generic confusion [Answered]

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:

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() saying it can't implicitly convert from Maybe to IFunctor<USelf, U>, except Maybe should implement IFunctor<USelf, U>, right?

4 Replies

ThinkerOP•3y ago

Tried changing the return type of the interface method to just USelf but that still causes the same error. oh USelf has no inherent connection to TSelf ughhh dammit generics catgrump

give us TSelf already

toddlahakbar•3y ago

What is the intent? Like of the TSelf vs T

ThinkerOP•3y ago

Yes, and that doesn't work I.e. it needs something like TSelf Which is why I said "so I know I'm kind of doomed from the start" Just had to rubber-duck myself to realize this isn't possible

Accord•3y ago

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TSelf generic confusion [Answered]