Aligned plain-text terminal table renderer

def format_row(cells : Array(String), widths : Array(Int32)) : String
  String.build do |io|
    cells.each_with_index do |cell, i|
      io << " | " if i > 0
      io << cell.ljust(widths[i])
    end
  end
end

def render_table(headers : Array(String), rows : Array(Array(String))) : String
  widths = headers.map(&.size)
  rows.each do |row|
    row.each_with_index { |cell, i| widths[i] = cell.size if cell.size > widths[i] }
  end
  lines = [format_row(headers, widths), widths.map { |w| "-" * w }.join("-+-")]
  rows.each { |row| lines << format_row(row, widths) }
  lines.join('\n')
end

puts render_table(["name", "role"], [["Ada", "engineer"], ["Bo", "ops"]])