Add Hashable typeclass
还没有人认领这个 Issue。
评估
- 难度
- 5/5
- 预计耗时
- 一周以上
- 新手友好度
- 20/100
- Issue 类型
- 功能
- 描述清晰度
- 基本清楚
- 活跃度
- 停滞
- 领域
- backend
调研方向
The issue proposes adding a Hashable typeclass to the prelude and deriving support to the compiler, but names no files or tests. Start by reviewing the existing Eq and Ord typeclasses and the linked purescript-unordered-collections implementation. Done means agreeing on the design and adding the prelude typeclass and compiler deriving support; the thread has had no comment for years, so check whether the proposal is still wanted.
由索引模型根据 Issue 内容生成。
描述
I would like to add a Hashable typeclass to the prelude and deriving support for it to the compiler. It is intended as an approximation of equality for use in hash-based algorithms and data structures, such as hash maps, not cryptographically secure digests or password hashes.
class Eq a <= Hashable a where
hash :: a -> Int
There are two reasons for adding it to the prelude instead of having a standalone library:
- Dependencies: To be useful in general data structures, as many datatypes as possible should be hashable. Ideally, whenever a datatype is
Eq, it should also haveOrdandHashableinstances, if possible. Most packages depend on the prelude already.[citation needed] This should make it easier to convince authors to addHashableinstances, because they do not need to add another dependency, all that is required is one more deriving line below the lines forEqandOrd. - Performance: Usually, the main goal of hashing is to avoid expensive comparisons. One could write a generic hash function in terms of
purescript-generics-rep. This would be fine for many applications, but for hash-based data structures etc., the hash function should really be as fast as possible.
I am more than happy to make an initial pull request (based on https://github.com/fehrenbach/purescript-unordered-collections/blob/master/src/Data/Hashable.purs) and work on deriving support.
What do people think?
- 主要语言
- PureScript
- 星标
- 168
- 派生
- 90
- 平均合并
- 3 天 1 小时
- 30 天内合并 PR
- 1
环境准备
- 没有 Dockerfile 或 Docker Compose 文件
- 有 Pull Request 模板
- 没有贡献指南
从这里开始
- 先读完整个 Issue，再读项目的贡献指南。
- 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
- Fork 仓库，在一个分支上完成修改。
- 提交 Pull Request，并在描述里引用这个 Issue 编号。
purescript/purescript-prelude 的其他 Issue
-
难度 2/5 1-3 小时 新手友好度 57/100
purescript/purescript-prelude#317 · 1 个 reaction ·
-
难度 3/5 1-2 天 新手友好度 32/100
purescript/purescript-prelude#312 · 5 条评论 ·
-
难度 5/5 一周以上 新手友好度 25/100
purescript/purescript-prelude#310 · 5 条评论 ·
-
难度 5/5 一周以上 新手友好度 24/100
purescript/purescript-prelude#308 · 2 条评论 ·
-
难度 3/5 1-2 天 新手友好度 35/100
purescript/purescript-prelude#307 · 1 条评论 · 1 个 reaction ·
查看 purescript/purescript-prelude 的全部 Issue
相似的 Issue
-
难度 2/5 1-3 小时 新手友好度 62/100
-
ManageSieve proxy: a backend's NO/BYE greeting is skipped as a capability line and reported as EOF未关闭bug
难度 2/5 1-3 小时 新手友好度 72/100
维护者通常 1 天内回复
-
Mend: dependency security vulnerability
难度 2/5 1-3 小时 新手友好度 65/100
-
Mend: dependency security vulnerability
难度 2/5 1-3 小时 新手友好度 62/100
ManageIQ/manageiq-pods#1476 ·
维护者通常 1 天内回复
-
难度 2/5 1-3 小时 新手友好度 62/100
prime-radiant-inc/evener#6366 ·
维护者通常 1 天内回复