#lang transd

MainModule: {
    hailstone: (λ n Int()
        (with seq Vector<Int>([n])
            (while (> n 1)
                (= n (if (mod n 2) (+ (* 3 n) 1)
                      else (/ n 2)))
                (append seq n)
            )
            (ret seq)
        )
    ),

    _start: (λ
        (with h (hailstone 27) l 0 n 0 t 0
            (lout "Length of (27): " (size h))
            (lout "First 4 of (27): " Range(in: h 0 4))
            (lout "Last 4 of (27): " Range(in: h -4 -0))
        (for i in Range(100000) do
            (= t (size (hailstone (to-Int i)))) (if (> t l) (= l t) (= n i))
        )
        (lout "For n < 100.000 the max. sequence length is " l " for " n)
        )
    )
}