RosettaCodeData/Task/CUSIP/Langur/cusip-2.langur

val isCusip = fn(s string) {
    if len(s) != 9 : return false

    val basechars = '0'..'9' ~ 'A'..'Z' ~ "*@#"

    val sum = for[=0] i of 8 {
        val c = s[i]
        var v = 0

        switch[and] c {
            case >= '0', <= '9':
                v = c-'0'

            case >= 'A', <= 'Z':
                v = c-55 # c-'A'+10

            case '*': v = 36
            case '@': v = 37
            case '#': v = 38

            default: return false
        }

        if i div 2: v *= 2
        _for += v \ 10 + v rem 10
    }

    s[9]-'0' == (10-(sum rem 10)) rem 10
}

val candidates = fw/037833100 17275R102 38259P508 594918104 68389X106 68389X105/

for c in candidates {
    writeln c, ": ", if(isCusip(c): "good" ; "bad")
}