Allow URIs specified in file directives implicitly It seems to me that, by specifying that one wants to serve a given file at a specified URI, one is implying that this URI should be allowed.

fun ack (m, n) =
    if m = 0 then
        n + 1
    else if n = 0 then
        ack (m - 1, 1)
    else
        ack (m - 1, ack (m, n - 1))

fun main n = return <xml>{[ack (n, 4)]}</xml>