Notes on 12 Jan. 2024

Agenda

Discuss Zygote PRs:

Minutes

Video link: https://youtu.be/8HOeSQSjSMc

PR: FluxML/Zygote.jl#1491

Tests pass, seems like a reasonable change
Are there unintended/untested consequences?
Based on linked Julia PR, semantics of accum should match x + y not x .+ y

PR: FluxML/Zygote.jl#1488

Change seems good to go
Minor issues like naming anonymous functions
Why is Base.Broadcast.Broadcasted(::Nothing) marked as non-differentiable?
- Enters call stack via copyto!(::Buffer, ::Broadcasted{Nothing}) mechanism
- But gradient should be nothing anyways

PR: FluxML/Zygote.jl#1489

Originally adapting Iterators.product pullback for scalar iterators, but augmented for inferrability
Scalar-related changes isolated to original lines 282 and 283—all other changes seem to be for type stability
Unclear why swapping ntuple construction for map is more type stable
Unclear why using a Vector{Int} for dims is more type stable than an ntuple
Changes for type stability appear to be functionally the same as original—so this is good to go sans uncertainty about why it is more type stable