get "libhdr"

let roman(s) = valof
$(  let digit(ch) = valof
    $(  let ds = table 'm','d','c','l','x','v','i'
        let vs = table 1000,500,100,50,10,5,1
        for i=0 to 6
            if ds!i=(ch|32) then resultis vs!i
        resultis 0
    $)
    let acc = 0
    for i=1 to s%0
    $(  let d = digit(s%i)
        if d=0 then resultis 0
        test i<s%0 & d<digit(s%(i+1))
            do acc := acc-d
            or acc := acc+d
    $)
    resultis acc
$)

let show(s) be writef("%S: %N*N", s, roman(s))

let start() be
$(  show("MCMXC")
    show("MDCLXVI")
    show("MMVII")
    show("MMXXI")
$)