copy of LazyArrays

[tlienart]

Long story short, the copy mechanism of apply arrays seems to cause issues in some problems, suggested alternative below.

context for this issue: JuliaData/Tables.jl#122 in particular reproducing MWE JuliaData/Tables.jl#122 (comment)

The problem identified by @nalimilan is:

AFAICT, the bug is that copy(A::ApplyArray) = ApplyArray(A.f, map(copy,A.args)...) when it should be copy(A::ApplyArray{T,N}) where {T,N} = ApplyArray{T,N}(A.f, map(copy,A.args)...). There may be other places with the same problem.

thoughts?

[dlfivefifty]

You are right: N cannot necessarily be determined automatically so should be part of the copy . Can you make a PR?

[tlienart]

Yes will do