[julia-users] how should I let this macro worked?

[Miao Yang]

macro awhen(expr, body...)
    esc(quote
        let it = $(expr)
          if it != nothing
            $(body...)
          end
        end
   end)
end

julia> @awhen([1, 2, 3], it[2]) # workds fine
2
julia> @awhen(nothing, it[2]) # workds fine

julia> @awhen([1, 2, 3], x = 1, it[x]) # :(, failed

ERROR: unsupported or misplaced expression kw


julia> macroexpand(:@awhen([1,2,3], x = 1, it[x]))
quote  # none, line 3:
    let it = [1,2,3] # line 4:
        if it != nothing # line 5:
            x=1
            it[x]
        end
    end
end


Have no idea how to let this worked...
Please help me, thanks.