But the iterator already existed. I find it easier to use the iterator to make a callback then to reimplement the algorithm recursively... (:

But enough good-natured intentionally talking at cross purposes... I was curious in what order your program produced the derangements and it told me: 

b a d c
b a d c
b a d c
b a d c
...

[download]

So I'll still keep my iterator-from-the-get-go. ;)

Update: If this "not too difficult" technique is too difficult for its own creator to correctly apply... And the point still stands that using an iterator via a call-back interface is trivial while using a call-back interface via an interator isn't even possible in stock Perl 5.

- tye        

In reply to Re^6: Derangements iterator (callbacks) by tye
in thread Derangements iterator by tye

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