y Scale options do not work for a list of functions properly

[CNOT]

I've got a function that as an input takes a list of values and returns an array of functions that I'd like to plot with Gadfly. Everything works fine until I try to plot it in any of the y-scales, then suddenly no plots are produced.
Here's a MWE:

using Gadfly
function test_f(a)
    return [x -> a[i]*x for i in 1:length(a)]
end
plot(test_f(1:10),1,2π) |> SVG("test.svg")

produces:

test.pdf

However,

plot(test_f(1:10),1,2π,Scale.y_log10()) |> SVG("test.svg")

fails to produce any plots and gives the following error:

MethodError: no method matching log10(::getfield(Main, Symbol("##10#12")){Int64,UnitRange{Int64}})
Closest candidates are:
log10(!Matched::BigFloat) at mpfr.jl:671
log10(!Matched::Missing) at math.jl:1072
log10(!Matched::Complex{Float16}) at math.jl:1020
...

[CNOT]

So I did some more digging, and I could be wrong but I believe the issue is that Gadfly doesn't use the ∘ operator for applying the composite functions that come up in Gadfly.Scale.

For example:

f = log10(x->x^2)

would produce a similar error to the one I posted earlier. However:

f = log10 ∘ (x->x^2)

seems to work properly.

[CNOT]

A workaround was suggested in Slack by Gerhard Aigner. I'll just write it down, in case anyone else ends up here facing the same issue.

Use Function in the function's definition:

function test_f(a)
    return Function[x -> a[i]*x for i in 1:length(a)]
end