Flat map is also a way to filter and transform at the same time, which is what the original function was doing.
Enum.reduce(ids, [], fn x, agg ->
case Integer.parse(x) do
{i,""} -> [i|agg]
_ -> agg
end
end)
Is equivalent to
Enum.flat_map(ids, fn x ->
case Integer.parse(x) do
{i,""} -> [i]
_ -> []
end
end)
Empty lists will be removed during the flatten.
EDIT: actually, the reduce version will reverse the list while flat_map will preserve the original order. So if you want to transform and filter flat_map is actually preferable.
