typelevel / typelevel/cats

Add Choice Profunctor

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Dominant language
Scala
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Description

Useful for bootstrapping pure profunctor lenses

trait Choice[~>[_, _]] extends Profunctor[~>] {
  def left[A, B, C](p: A ~> B): (C Xor A) ~> (C Xor B)
  def right[A, B, C](p: A ~> B): (A Xor C) ~> (B Xor C)
}

object Choice {
  def apply[F[_, _]](implicit ev: Choice[F]): Choice[F] = ev
}

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating the existing Profunctor definition and related typeclass patterns in the Cats source. Implement the Choice API shown in the issue, then identify the relevant tests or instance coverage and verify that the new typeclass integrates with the existing profunctor abstractions.

Written by the indexing model from the issue text.

Assessment

Tech stack
scala
Domain
tooling
Issue type
Feature
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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