A small, but relevant update. With this version of DataFrames.jl we also re-export a new version of Missings.jl, which introduces passmissing function. We would welcome a feedback on this functionality (as it might eventually be considered for inclusion into Julia Base).
The passmissing function wraps any Julia function f (typically missing “unaware”) accepting positional arguments so that if any of them is missing it returns missing and otherwise calls f with the passed arguments. Here is an example showing you the difference:
julia> string(missing, " ", missing)
"missing missing"
julia> passmissing(string)(missing, " ", missing)
missing