FluxML/Zygote.jl

Use ChainRules types

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#603 创建于 2020年4月20日

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 (5 评论) (5 反应) (0 负责人)Julia (1,568 star) (220 fork)batch import
ChainRuleshelp wantedup for grabs

描述

This issue is about swapping Zygote over to use ChainRule's types by default. When #366 is merged rules coming out of ChainRules will use its types like Composite and AbstractZero, but thing created via Source Code Transform (SCT) will still use NamedTuple and nothing.

This is fine as they are mutually compatible because accum falls back to + and ChainRules overloads +.

The use of Base types in Zygote tends to cause issues as its hard to add methods for NamedTuple and nothing, due to type piracy. Especially things like defining linear operations on them (e.g. overloading things from LinearAlgebra), as well as defining addition +. Particular discussion on Composite ans structured differential types is in #462

Related to: #454 #419 #329

贡献者指南

技术栈
无
领域
machine learning
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。
3-5 days
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。
mostly clear
前置要求
Julia programmingAutomatic differentiation conceptsZygote.jl internals
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。
25
研究方向
Investigate the current usage of NamedTuple and nothing in Zygote's source code transform (SCT). Review ChainRules types Composite and AbstractZero as defined in ChainRules.jl. Examine the related issues #366, #462, #454, #419, #329 for context and prior discussion. Implement the swap ensuring backward compatibility via accum fallback.