RosettaCodeData/Task/CUSIP/Langur/cusip-1.langur

val .isCusip = fn(.s) {
    if .s is not string or len(.s) != 9 {
        return false
    }

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

    val .sum = for[=0] .i of 8 {
        var .v = index(s2s(.s, .i), .basechars)
        if not .v: return false
        .v = .v[1]-1
        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")
}