#lang transd

MainModule: {
    // Define an abstract type Vec to make the shuffling
    // function polymorphic
    Vec: typedef(Lambda<:Data Bool>(λ d :Data()
        (starts-with (_META_type d) "Vector<"))),

    kshuffle: (λ v Vec() locals: rnd 0
        (for n in Range( (- (size v) 1) 0) do
            (= rnd (randr (to-Int n)))
            (with tmp (cp (get v n))
                (set-el v n (get v rnd))
                (set-el v rnd tmp))
        )
        (lout v)
    ),
	_start: (λ
        (with v [10,20,30,40,50,60,70,80,90,100]
            (lout "Original:\n" v)
            (lout "Shuffled:")
            (kshuffle v))
        (lout "")
        (with v ["A","B","C","D","E","F","G","H"]
            (lout "Original:\n" v)
            (lout "Shuffled:")
            (kshuffle (cp v))
            // Transd has a built-in function that performs the same
            // kind of random shuffle
            (lout "Built-in shuffle:")
            (lout (shuffle v)))
    )
}