view of PooledArray

[bkamins]

CategoricalArrays.jl handles DataAPI.refarray, DataAPI.refvalue, and DataAPI.refpool correctly for views. I propose to add the same for PooledArrays.jl (now views return nothing from DataAPI.refpool).

[oxinabox]

It would also be good if views of PooledArrays still had fast map that runs once per pool element

PooledArrays.jl/src/PooledArrays.jl

Line 307 in 080771a

function Base.map(f, x::PooledArray{T,R}) where {T,R<:Integer}

[bkamins]

Related is: #36.

Also the problem is that function passed to map does not have to be pure, in which case you should apply it to each element of the array.