typelevel/cats

Add Divisible and Decideable (contravariant Applicative and co.)

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#1,935 创建于 2017年9月27日

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 (22 评论) (5 反应) (0 负责人)Scala (5,438 star) (1,241 fork)batch import
help wanted

描述

https://hackage.haskell.org/package/contravariant-1.4/docs/Data-Functor-Contravariant-Divisible.html

Example use case: divide can be seen as a way of deriving behavior by splitting a "larger" type in two

贡献者指南

技术栈
scala
领域
backend
议题类型
feature
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
4
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
over 1 week
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
stale
清晰度议题是否清楚说明期望改动、验收标准和下一步。
needs investigation
前置要求
cats library basicstype classescontravariant functorsscala syntax
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
15
研究方向
Research the Divisible and Decidable type classes from the Haskell contravariant package (https://hackage.haskell.org/package/contravariant 1.4/docs/Data Functor Contravariant Divisible.html). Study the existing Contravariant type class in cats (e.g., cats core/src/main/scala/cats/Contravariant.scala) to understand the pattern. Define new Divisible and Decidable traits and provide instances for common types. Since the issue has been open long, consider posting a design proposal before implementation to ensure maintainer alignment.