Ability to add calculated columns

[buren]

Ideas 💡

Alternative 1

With argument

HoneyFormat::Matrix.new(
  data,
  calculated_columns: [[
    :full_name,
    proc { |row| "#{row.first_name} #{row.last_name}" }
  ], [
    :can_vote?,
    proc { |row| row.age }
  ]]
)

Don't like the name calculated_columns

Alternative 2

With builder

HoneyFormat::Matrix.new(data) do |builder|
  builder.add_column(
    :full_name,
    proc { |row| "#{row.first_name} #{row.last_name}" }
  )
end

If going with this we'd need to set/configure other things the same way like builder.type_map({ username: proc { |v| v.upcase } }).