extractRange = function(ints)
    result = []
    idx = 0
    while idx < ints.len
        runLen = 1
        while idx+runLen < ints.len and ints[idx+runLen] == ints[idx] + runLen
            runLen = runLen + 1
        end while
        if runLen > 2 then
            result.push ints[idx] + "-" + ints[idx+runLen-1]
            idx = idx + runLen
        else
            result.push ints[idx]
            idx = idx + 1
        end if
    end while
    return join(result, ",")
end function

test = [ 0,  1,  2,  4,  6,  7,  8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
   25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39]
print extractRange(test)