$ include "seed7_05.s7i";

const func integer: ROMAN parse (in string: roman) is func
  result
    var integer: arabic is 0;
  local
    var integer: index is 0;
    var integer: number is 0;
    var integer: lastval is 0;
  begin
    for index range length(roman) downto 1 do
      case roman[index] of
        when {'M', 'm'}: number := 1000;
        when {'D', 'd'}: number :=  500;
        when {'C', 'c'}: number :=  100;
        when {'L', 'l'}: number :=   50;
        when {'X', 'x'}: number :=   10;
        when {'V', 'v'}: number :=    5;
        when {'I', 'i'}: number :=    1;
        otherwise:       raise RANGE_ERROR;
      end case;
      if number < lastval then
        arabic -:= number;
      else
        arabic +:= number;
      end if;
      lastval := number;
    end for;
  end func;

const proc: main is func
  begin
    writeln(ROMAN parse "MCMXC");
    writeln(ROMAN parse "MMVIII");
    writeln(ROMAN parse "MDCLXVI");
  end func;