ZeroMean{Float64} is not callable

[theogf]

So diligently using ColVecs 😄 I faced the following bug when trying to optimize kernel parameters. Here is the MWE

using AbstractGPs, KernelFunctions, Flux
X = rand(2, 10)
y = rand(10)
l = rand(2)
k = transform(SqExponentialKernel(), l)
Flux.gradient(Flux.params(k)) do
    m = GP(k)(KernelFunctions.ColVecs(X), 0.01)
    logpdf(m, y)
end

And get the error LoadError: MethodError: objects of type AbstractGPs.ZeroMean{Float64} are not callable

One additional note : KernelFunctions and ColVecs/RowVecs should be exported.

[willtebbutt]

This will be resolved by #16 -- just need to wait for Flux to allow Zygote 0.5 .

[theogf]

I am afraid this is still not working with AbstractGPs 0.2.3, Flux 0.11.0 and Zygote 0.5.3.
The rrule you defined never seems to be called...

[willtebbutt]

Same error?

[theogf]

Yes :

ERROR: MethodError: objects of type AbstractGPs.ZeroMean{Float64} are not callable
Stacktrace:
 [1] macro expansion at /home/theo/.julia/packages/Zygote/iFibI/src/compiler/interface2.jl:0 [inlined]
 [2] _pullback(::Zygote.Context, ::AbstractGPs.ZeroMean{Float64}, ::SubArray{Float64,1,Array{Float64,2},Tuple{Base.Slice{Base.OneTo{Int64}},Int64},true}) at /home/theo/.julia/packages/Zygote/iFibI/src/compiler/interface2.jl:13
 [3] (::Zygote.var"#586#590"{Zygote.Context,AbstractGPs.ZeroMean{Float64}})(::SubArray{Float64,1,Array{Float64,2},Tuple{Base.Slice{Base.OneTo{Int64}},Int64},true}) at /home/theo/.julia/packages/Zygote/iFibI/src/lib/array.jl:176
 [4] iterate at ./generator.jl:47 [inlined]
 [5] _collect at ./array.jl:678 [inlined]
 [6] collect_similar at ./array.jl:607 [inlined]
 [7] map at ./abstractarray.jl:2072 [inlined]
 [8] ∇map at /home/theo/.julia/packages/Zygote/iFibI/src/lib/array.jl:176 [inlined]
 [9] adjoint at /home/theo/.julia/packages/Zygote/iFibI/src/lib/array.jl:191 [inlined]
 [10] _pullback at /home/theo/.julia/packages/ZygoteRules/6nssF/src/adjoint.jl:47 [inlined]
 [11] mean at /home/theo/.julia/dev/AbstractGPs/src/gp/gp.jl:67 [inlined]

[willtebbutt]

Could you also provide your completely ] st?

[theogf]

(@v1.4) pkg> st Zygote Flux AbstractGPs ChainRulesCore
Status `~/.julia/environments/v1.4/Project.toml`
  [99985d1d] AbstractGPs v0.2.3 [`~/.julia/dev/AbstractGPs`]
  [d360d2e6] ChainRulesCore v0.9.5
  [587475ba] Flux v0.11.0
  [e88e6eb3] Zygote v0.5.3

[theogf]

Hey back to this beautiful topic. As in KernelFunctions.jl, replacing Base.map by _map everywhere solves the problem.
I know it's not the best way but at least it works. What do you think @willtebbutt, should I make a PR to correct it?

[willtebbutt]

A PR would be welcome for now I reckon -- it continues to make me very sad, but I don't think that we have a better solution right now.