ericelliott/rtype

declaration-site variance annotations of generic type arguments

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#81 opened on Apr 14, 2016

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help wantedstrawman

Description

Declaration-site variance annotations in other languages

C#, Kotlin, Ceylon:

  • out covariance
  • in contravariance

Scala, OCaml, Flow:

  • + covariance
  • - contravariance

What should we choose? (see discussion about generic types in #55 and #80)

Contributor guide

Tech stack
javascript
Domain
developer experience
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Understanding of type variance concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
10
Research direction
Review the discussion in issues #55 and #80, and examine how other languages implement variance annotations (C#, Kotlin, Scala, etc.). The community needs to decide on a syntax (e.g., out/in or +/ ). Consider contributing a proposal or poll within the issue to reach consensus. No code changes are required yet; this is a design discussion.