Extending typeclass defined parametrically from typeclass defined using Self type member

Question
1

My question regards the new typeclass syntax introduced with the experimental.modularity feature set.

I want to define a typeclass Lattice { type Self }, which ought to extend the already existing PartialOrdering[T] typeclass. I’m really enjoying the new Self member type syntax, and am using it throughout my project. Is there anyway I can define Lattice using the new syntax, and still extend PartialOrdering[T]? Something akin to trait Lattice extends PartialOrdering[this.Self]?

2

Welcome to the Scala community @erik1 :waving_hand:

I don’t know the answer to your question (haven’t used the new syntax yet), but just to get the ball rolling, do you mean a “new syntax equivalent” of:

trait Lattice extends PartialOrdering[Lattice]
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3

No that would not work, unfortunately. You can’t use this in parent types. We still have to figure out how to best blend parameters and type members in these cases.

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4

Okay, understood. Thanks for the reply

5

That’s not quite what I’m looking for. I want the Lattice typeclass to extend the PartialOrdering typeclass. If I was using the old syntax I could achieve this as follows: trait Lattice[T] extends PartialOrdering[T].

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